JP7736080B2 - Optical element, optical integrated element, and method for manufacturing optical integrated element - Google Patents

Description

The present invention relates to an optical element for connecting optical elements, an optical integrated element, and a method for manufacturing an optical integrated element.

As optical communication networks advance, there is a demand for more sophisticated and cost-effective optical communication devices. Optical communication devices require electrical elements such as drivers, switches, and electrical amplifier circuits, as well as optical elements such as semiconductor lasers, optical switches, and optical fibers.

In the optical connection process where each optical element is discretely connected, precise positioning between optical elements is important to achieve low-loss optical connections. For this reason, even commonly used optical connectors use high-precision components that achieve optical axis misalignment between waveguide cores of 1 μm or less. Thus, when manufacturing optical communication devices, designs and precision components that take strict tolerances into account are important.

In particular, SiPh (Silicon Photonics) poses a challenge in terms of optical mounting positioning accuracy. SiPh is an optical device with semiconductor materials at its core, which not only enables the creation of ultra-compact, highly economical optical circuits, but also allows for high-density integration with electrical circuit elements.

However, SiPh requires higher alignment accuracy and stricter tolerances during connection than conventional silica-core devices such as PLCs (Planar Lightwave Circuits), posing a problem of increased process load for optical connections. This is because the smaller the optical mode field diameter (MFD), the stricter the tolerance requirements during optical connection. Therefore, optical connections for SiPh, which are semiconductor-based optical circuit devices with a minute MFD, require more precise alignment technology.

On the other hand, increasing the MFD allows for more relaxed positioning accuracy. However, with SiPh, the thickness of each layer during manufacturing is limited, and the high refractive index inherent in semiconductor waveguides causes high loss due to roughness on the waveguide sidewalls. Therefore, compared to conventional optical elements such as PLCs, it is difficult to achieve an MFD with low loss and high yield comparable to that of conventional optical fibers.

For this reason, a method of converting the MFD of the optical element (chip) and optical fiber to an MFD of approximately 4 μm, smaller than the approximately 10 μm MFD of conventional optical fibers, is used for low-loss optical connections. However, when using this method, the small MFD requires high positioning accuracy on the submicron level, which means stricter positioning accuracy during optical connection and tolerances required for optical components.

Self-written waveguides (hereinafter referred to as "SWW") have been disclosed as a technology that can alleviate the positioning accuracy required for this connection (Non-Patent Document 1).

This technology is an optical connection technology that uses a photocurable resin and can connect waveguide cores as follows: Here, light used as signal light for optical communications (hereinafter referred to as "signal light") is emitted from the end face of at least one of the waveguide cores.

To form the SWW, first, photocurable resin is dripped into the gaps between the waveguide cores.

Next, resin curing light, which is light for curing the photocurable resin, is irradiated from both or one of the waveguide cores. At this time, due to the property of photocurable resin, which is to cure sequentially from the area with the highest light intensity, SWW cores (hereinafter referred to as "SWW cores") are formed sequentially from the end face of each waveguide core. As a result, SWW cores are formed at the end faces of the waveguide cores.

In addition, since the SWW core is formed according to the propagation path of the resin curing light, even if an optical axis misalignment occurs between the waveguide cores, an S-shaped bent SWW core is formed to compensate for the optical axis misalignment, thereby achieving low-loss optical connection.

Finally, if necessary, remove any uncured portions of the photocurable resin by cleaning or other means, then drip cladding resin onto the removed portion (around the SWW core) and allow it to harden appropriately to form the SWW cladding (hereinafter referred to as "SWW cladding"), completing the SWW connection.

In this way, this technology has the effect of compensating for axial misalignment, enabling low-loss connections even when there is a gap between waveguide cores or misalignment of the optical axis, which are factors that cause connection loss between waveguide cores. Therefore, SWW optical connection technology can relax tolerance requirements for the components that make up optical devices, enabling simple optical integration and high-yield, low-loss implementation.

The SWW formation process also enables the formation of spot-size converters (SSCs), which are essential for connecting waveguide cores with different MFDs. This is useful for optical fiber implementation on SiPh chips with small MFDs.

As shown in Figure 22, the SWW is applied to the optical connection between an optical element 71 such as a SiPh chip and optical waveguide elements 72_1 and 72_2 such as optical fibers. The optical element such as a SiPh chip is composed of an optical planar circuit consisting of a first waveguide core 711 and second waveguide cores 712_1 and 712_2.

An optical multiplexer/demultiplexer 714 is also formed on the SiPh chip (optical element). Figure 22 shows an example in which a Y-branch structure is formed using a Y-shaped waveguide structure, but any known optical multiplexer/demultiplexer structure with similar functionality can be used. As shown in Figure 23, the optical multiplexer/demultiplexer 714 is composed of a first waveguide core 711, a mode field conversion section 713 fabricated at one end of the first waveguide core 711, and a second waveguide core 712_2 that covers it. The mode field conversion section 713 allows signal light 2 to transition between the first waveguide core 711 and the second waveguide core 712_2.

Figures 24 and 25 show cross-sectional views taken along lines XXIV-XXIV' and XXV-XXV' in Figure 23, respectively. In the optical multiplexing/demultiplexing section 714, a first waveguide core 711 is formed on the lower cladding section 710_2 by photolithography or the like. A second waveguide core 712_2 is formed to cover the first waveguide core 711, and an upper cladding section 710 is formed to cover the upper surface of the second waveguide core 712_2.

The cross section of the optical multiplexing/demultiplexing section 714 is composed of two parts: a part formed only by the second waveguide core 712_2, as shown in the XXIV-XXIV' cross section (Figure 24), and a part having the first waveguide core 711, as shown in the XXV-XXV' cross section (Figure 25).

In SiPh chips (optical elements), visible light is emitted from the waveguide end face by using a waveguide material that can be integrated into SiPh and is transparent to the visible light used in SWW. This is because resin curing light 1 (mainly visible light) is barely able to propagate through the Si waveguide in SiPh due to material absorption, so the use of a different transparent material makes it possible to apply SWW.

In this way, the SiPh chip (optical element) is equipped with an optical multiplexer/demultiplexer 714, which allows signal light (light in the wavelength band used for optical communications) 2 and resin curing light 1, which are important for optical connections via SWW, to be coupled into the same waveguide core. The optical multiplexer/demultiplexer 714 can use, for example, a Y-branch structure. By using the optical multiplexer/demultiplexer 714, resin curing light 1 can be coupled from the outside into the same waveguide (second waveguide core 712_2) as signal light 2, and resin curing light 1 can be emitted from the end face of the SiPh chip.

In addition, second waveguide cores 712_1 and 712_2 are formed separately from the first waveguide core 711 through which signal light 2 propagates. The second waveguide cores 712_1 and 712_2 are formed for visible light transmission, and by inputting resin curing light 1 into the second waveguide core 712_1 using an optical fiber (optical fiber for inputting resin curing light) 72_1 or the like, light can be emitted from the waveguide core end face of the optical element facing the signal light input/output optical fiber 72_2. This allows resin curing light 1 to be output from each of the end faces of the signal light input/output optical fiber 72_2 and the optical element 71 facing it, achieving optical connection via SWW.

In the configuration shown in Figure 22, by providing an optical fiber 72_1 for inputting resin curing light, it becomes possible to emit resin curing light 1 from the waveguide end face of the optical element facing the optical fiber 72_2 for inputting and outputting signal light via the path shown in Figure 23. This makes it possible to emit resin curing light 1 from both waveguide end faces between the connecting waveguides, thereby realizing optical connection using SWW.

Hirose, Naohiro et al., "Optical Simple Interconnection Technology Using Self-Written Waveguides," Journal of the Japan Institute of Electronics Packaging, Vol. 5, No. 5, (2002).

However, with the above configuration, it was necessary to prepare an optical fiber for inputting and outputting the resin curing light separately from the optical fiber for inputting and outputting the signal light. Thus, while optical connections using SWW allow for relaxed positioning accuracy, there was a problem in that it was necessary to prepare a separate optical fiber that was not used for optical communications.

In order to solve the above-mentioned problems, an optical element according to the present invention is an optical element connected to a set of optical waveguide elements via a set of third waveguide cores, and comprises a set of first waveguide cores, a set of second waveguide cores, and a connecting waveguide, wherein the refractive index of the first waveguide core is greater than the refractive index of the second waveguide core, the first waveguide core has a mode field converting portion, at least the mode field converting portion is covered by the second waveguide core, and the connecting waveguide is connected to a front end of the first waveguide element via an optical multiplexing/demultiplexing portion. The set of second waveguides is connected, one of the second waveguide cores is connected to one of the optical waveguide elements at a predetermined end face of the optical element via one of the third waveguide cores, the other of the second waveguide cores is connected to the other of the optical waveguide elements at the predetermined end face via the other of the third waveguide cores, and the third waveguide core is connected to a set of photocurable resins arranged in a gap between the set of optical waveguide elements and the set of second waveguide cores, the refractive index of which is changed by irradiation of a set of resin curing light. one of the resin curing lights is emitted from the one of the optical waveguide elements and irradiated onto one of the photocurable resins arranged on the predetermined end face, and the other of the resin curing lights is emitted from the other of the optical waveguide elements, propagates through the other of the second waveguide cores, the connection waveguide, and the one of the second waveguide cores in order, is emitted from an end face of the one of the second waveguide cores at the predetermined end face, is irradiated onto one of the photocurable resins, and is irradiated onto the other of the resin curing lights. light is emitted from the other optical waveguide element and irradiated onto the other photocurable resin arranged on the predetermined end face, and the one resin curing light is emitted from the one optical waveguide element, propagates in order through the one third waveguide core, the one second waveguide core, the connecting waveguide, and the other second waveguide core, is emitted from an end face of the other second waveguide core at the predetermined end face, and is irradiated onto the other photocurable resin .

Furthermore, an optical integrated device according to the present invention comprises an optical device having a set of first waveguide cores, a set of second waveguide cores, and a connecting waveguide; a set of optical waveguide elements for inputting and outputting optical communication signals; and a set of optical connecting portions having a third waveguide core, wherein one of the second waveguide cores and one of the optical waveguide elements are connected at a predetermined end face of the optical device via the third waveguide core of one of the optical connecting portions, and the other of the second waveguide cores and the other of the optical waveguide elements are connected at the predetermined end face . the first waveguide core has a mode field conversion section and is covered by the second waveguide core, the connecting waveguide connects the set of second waveguides via an optical multiplexing/demultiplexing section, the third waveguide core is a part in which a refractive index is changed by irradiation of a set of resin curing light in a set of photocurable resin arranged in a gap between the set of optical waveguide elements and the set of second waveguide cores, and one of the resin curing light is The resin curing light is emitted from one of the optical waveguide elements and irradiated onto one of the photocurable resins arranged on the predetermined end face, and the other resin curing light is emitted from the other of the optical waveguide elements and propagates through the other of the second waveguide cores, the connecting waveguide, and one of the second waveguide cores in order, and is emitted from an end face of one of the second waveguide cores at the predetermined end face and irradiated onto one of the photocurable resins ... then transmitted to the other of the optical waveguide elements. the resin-curing light is emitted from one of the optical waveguide elements, propagates through the third waveguide core of the one of the optical connection parts, the second waveguide core of the one of the optical waveguide elements, the connecting waveguide, and the second waveguide core of the other of the optical connection parts, and is emitted from an end face of the other of the second waveguide cores at the predetermined end face, and is irradiated onto the other of the photo-curing resins .

Furthermore, a method for manufacturing an optical integrated element according to the present invention includes the steps of: arranging an end face of an optical element having a set of first waveguide cores, a set of second waveguide cores, and a connecting waveguide connecting the set of second waveguide cores, and an end face of a set of optical waveguide elements so as to face each other; aligning the center of the second waveguide core with the center of the optical waveguide elements; disposing one photocurable resin in a gap between an end face of one of the second waveguide cores at the end face of the optical element and an end face of one of the optical waveguide elements; disposing the other photocurable resin in a gap between an end face of the other of the second waveguide cores at the end face of the optical element and an end face of the other optical waveguide element; irradiating one resin curing light onto the one optical waveguide element and irradiating the one photocurable resin to at least partially form one self-forming waveguide; and irradiating the other resin curing light onto the other optical waveguide element. the resin-curing light is incident on the other optical waveguide element, and is irradiated onto the other photo-curable resin, thereby at least partially forming the other self-forming waveguide; and the resin-curing light is incident on the one optical waveguide element, and is propagated into the one self -forming waveguide, the one second waveguide core, the connecting waveguide, and the other second waveguide core, thereby exiting from the end face of the other second waveguide core, and is irradiated onto the other photo-curable resin, thereby at least partially forming the other self-forming waveguide.

According to the present invention, the optical fiber for inputting resin curing light, which was previously required, is no longer necessary, thereby reducing the manufacturing costs of optical elements and optical integrated elements and allowing for an increase in the number of signal optical fibers that can be mounted on optical elements and optical integrated elements.

FIG. 1 is a schematic top perspective view showing the configuration of an optical element and an optical integrated element according to a first embodiment of the present invention. FIG. 2 is a schematic top perspective view showing the configuration of the optical element according to the first embodiment of the present invention. FIG. 3 is a diagram for explaining a method for manufacturing an integrated optical device according to the first embodiment of the present invention. FIG. 4 is a diagram for explaining a method for manufacturing an integrated optical device according to the first embodiment of the present invention. FIG. 5 is a diagram for explaining a method for manufacturing an integrated optical device according to the first embodiment of the present invention. FIG. 6 is a diagram for explaining a method for manufacturing an integrated optical device according to the first embodiment of the present invention. FIG. 7 is a schematic top perspective view showing an example of the configuration of the optical element and the optical integrated element according to the first embodiment of the present invention. FIG. 8 is a schematic top perspective view showing an example of the configuration of the optical element and the optical integrated element according to the first embodiment of the present invention. FIG. 9 is a schematic top perspective view showing an example of the configuration of an optical element according to the first embodiment of the present invention. FIG. 10 is a schematic top perspective view showing the configuration of an optical element and an optical integrated element according to the second embodiment of the present invention. FIG. 11 is a schematic top perspective view showing an example of the configuration of an optical element and an optical integrated element according to the second embodiment of the present invention. FIG. 12 is a schematic top perspective view showing an example of the configuration of an optical element and an optical integrated element according to the second embodiment of the present invention. FIG. 13 is a schematic top perspective view showing the configuration of an optical element and an optical integrated element according to the third embodiment of the present invention. FIG. 14 is a schematic top perspective view showing an example of the configuration of an optical element and an optical integrated element according to the third embodiment of the present invention. FIG. 15 is a schematic top perspective view showing an example of the configuration of an optical element and an optical integrated element according to the third embodiment of the present invention. FIG. 16 is a schematic top perspective view showing the configuration of an optical element and an optical integrated element according to the fourth embodiment of the present invention. FIG. 17 is a diagram for explaining the operation of the optical element and the optical integrated element according to the fourth embodiment of the present invention. FIG. 18A is a schematic top perspective view showing the configuration of an optical element and an optical integrated element according to a fifth embodiment of the present invention. FIG. 18B is a diagram for explaining the operation of the optical element and the optical integrated element according to the fifth embodiment of the present invention. FIG. 19 is a schematic top perspective view showing the configuration of an optical element and an optical integrated element according to the sixth embodiment of the present invention. FIG. 20 is a schematic top perspective view showing an example of the configuration of a portion of an optical element according to the sixth embodiment of the present invention. FIG. 21 is a schematic top perspective view showing an example of the configuration of a portion of an optical element according to the sixth embodiment of the present invention. FIG. 22 is a schematic top perspective view showing the configuration of a conventional optical element and an optical integrated element. FIG. 23 is a schematic top perspective view showing the configuration of a portion of a conventional optical element. FIG. 24 is a schematic top perspective view showing the configuration of a part of a conventional optical element. FIG. 25 is a schematic top perspective view showing the configuration of a part of a conventional optical element.

First Embodiment
An optical element and an optical integrated element according to a first embodiment of the present invention will be described with reference to FIGS.

<Configuration of optical integrated device>
As shown in FIG. 1, an optical integrated device 10 according to this embodiment includes an optical device 11, an optical fiber 12, and an optical connection portion 13.

The optical element 11 comprises two waveguide sections, an upper cladding section 110 and a lower cladding section (not shown) above and below them. One of the waveguide sections comprises a first waveguide core 111_1 and a second waveguide core 112_1, and has a mode field conversion section 113_1 at the tip of the first waveguide core 111_1. The second waveguide core 112_1 also has an optical multiplexing/demultiplexing section 114_1.

Similarly, the other waveguide section has a first waveguide core 111_2 and a second waveguide core 112_2, and has a mode field conversion section 113_2 at the tip of the first waveguide core 111_2. Also, the second waveguide core 112_2 has an optical multiplexing/demultiplexing section 114_2.

The second waveguide core 112_1 of one waveguide section and the second waveguide core 112_2 of the other waveguide section are connected by a connecting waveguide 115 via optical multiplexing/demultiplexing sections 114_1 and 114_2, respectively. Here, the connecting waveguide 115 has the same configuration as the second waveguide cores 112_1 and 112_2.

At the input/output end face of the optical element 11, one optical fiber 12_1 and the other optical fiber 12_2 are connected to one second waveguide core 112_1 and the other second waveguide core 112_2, respectively, via optical connection portions 13_1 and 13_2.

One optical connection portion 13_1 and the other optical connection portion 13_2 each have a third waveguide core 131_1, 131_2 and a third waveguide clad 132_1, 132_2 surrounding it.

The optical element 11 has a circuit structure in which first waveguide cores 111_1 and 111_2, each equipped with a mode field conversion section 113_1 and 113_2, are covered by second waveguide cores 112_1 and 112_2. The upper cladding section 110 and the lower cladding section of the optical element 11 are made of, for example, silicon oxide, but may be made of other materials that function as cladding sections.

In the optical element 11, for example, the first waveguide cores 111_1 and 111_2 are made of Si, and the second waveguide cores 112_1 and 112_2 are made of SiON, which is made by adding nitrogen to silicon oxide.

Alternatively, InP may be used for the first waveguide cores 111_1 and 111_2, and SiOx or a resin material may be used for the second waveguide cores 112_1 and 112_2.

Here, the refractive index of the first waveguide cores 111_1 and 111_2 must be higher than the refractive index of the second waveguide cores 112_1 and 112_2.

Furthermore, the first waveguide cores 111_1 and 111_2 are covered by the second waveguide cores 112_1 and 112_2, and the second waveguide cores 112_1 and 112_2 are transparent to visible light.

The structure comprising first waveguide cores 111_1 and 111_2, second waveguide cores 112_1 and 112_2, and mode field conversion sections 113_1 and 113_2 adiabatically transfers light to cores with different cross-sectional areas. In other words, the mode field conversion sections 113_1 and 113_2 enable low-loss coupling between waveguides with different MFDs.

In the mode field conversion sections 113_1 and 113_2, as the core width gradually narrows toward the tip of the tapered section of the first waveguide cores 111_1 and 111_2, the signal light confined in the first waveguide cores 111_1 and 111_2 becomes weaker, and the MFD gradually expands into the second waveguide cores 112_1 and 112_2.

The signal light then transitions to an optical mode propagating within the second waveguide cores 112_1 and 112_2 and propagates therethrough. As a result, the signal light that has transitioned to the second waveguide cores 112_1 and 112_2 is emitted from the output end face of the optical element 11.

Here, if at least the mode field conversion sections 113_1 and 113_2 in the first waveguide cores 111_1 and 111_2 are covered by the second waveguide cores 112_1 and 112_2, the signal light can be propagated as described above.

In addition, the mode field conversion sections 113_1 and 113_2 may have a structure other than the simple tapered structure in which the core width narrows as it approaches the tip of the first waveguide cores 111_1 and 111_2 shown in Figure 2, such as a tapered structure with a three-pronged tip.

It is also preferable to position the optical multiplexing/demultiplexing sections 114_1 and 114_2 at a distance of several tens of μm or more from the mode field conversion sections 113_1 and 113_2 toward the interior of the optical element 11 (the side opposite the tip end of the first waveguide core, i.e., the base end side of the first waveguide core). Hereinafter, the interior side of the optical element 11 will be referred to as the "base end side of the first waveguide core (or second waveguide core)."

This allows the resin curing light to be coupled in the optical multiplexing/demultiplexing units 114_1 and 114_2 while minimizing the impact on the mode field conversion function that expands the MFD of the signal light. Details are explained below.

If the optical multiplexing/demultiplexing section were placed in the mode field conversion section, the signal light propagating through the first waveguide core would gradually seep into the second waveguide core, causing the signal light to be affected by the Y-branch of the optical multiplexing/demultiplexing section, resulting in losses and affecting mode field conversion during signal light propagation (signal transmission).

On the other hand, when the optical multiplexing/demultiplexing sections 114_1 and 114_2 are positioned away from the mode field conversion sections 113_1 and 113_2, the signal light is sufficiently confined to the base end side of the mode field conversion sections 113_1 and 113_2 of the first waveguide cores 111_1 and 111_2.

Here, the side surfaces of the first waveguide cores 111_1 and 111_2 and the side surfaces of the second waveguide cores 112_1 and 112_2 are separated in the width direction of the cores to an extent that they do not have an optical effect. For example, the width of the first waveguide cores 111_1 and 111_2 is approximately 400 nm, while the width of the second waveguide cores 112_1 and 112_2 is approximately 3 μm.

In this way, the Y-shaped optical multiplexing/demultiplexing sections 114_1 and 114_2 are more than 1 μm away from the region where the signal light is confined. As a result, due to the above-mentioned arrangement of the optical multiplexing/demultiplexing sections 114_1 and 114_2, the signal light is not optically affected by the Y branching of the optical multiplexing/demultiplexing sections 114_1 and 114_2.

Therefore, it is preferable to position the optical multiplexing/demultiplexing sections 114_1 and 114_2 away from the mode field conversion sections 113_1 and 113_2 toward the base end of the second waveguide core.

As shown in Figure 2, the structure of the optical element 11 has the same configuration as the second waveguide cores 112_1 and 112_2, and differs from conventional structures in that adjacent optical multiplexing/demultiplexing sections 114_1 and 114_2 are connected by a connecting waveguide 115 having a curved waveguide. This structure allows the optical fiber for inputting and outputting signal light to be used as the optical fiber for inputting resin curing light, thereby reducing the number of fiber cores required for connection.

<Method of manufacturing an optical integrated device>
A method for manufacturing the integrated optical device 10 according to this embodiment will be described with reference to FIGS.

First, the optical element 11 and two optical fibers 12_1 and 12_2 for inputting and outputting signal light are positioned, and the centers of the optical fibers 12_1 and 12_2 for inputting and outputting signal light are aligned with the centers of the second waveguide cores 112_1 and 112_2 of the optical element 11 (Figure 3).

The alignment process can be performed using known alignment methods. For example, active alignment can be performed using signal light, or image alignment can be performed using the outer diameter of the chip or fiber as a reference. Furthermore, when using a SiON core, image alignment can also be performed using visible light. For example, image alignment can be performed while emitting resin curing light, and rough alignment can be performed using as a marker the coordinates where the resin curing light is strongly scattered in the SiON core.

Next, as shown in Figure 4, photocurable resin 14_1 is dripped into the gap between one of the signal light input/output optical fibers 12_1 and the second waveguide core 112_1 of the optical element 11. This process can be performed using, for example, a dispenser.

The absorption loss of the photocurable resin with respect to the resin curing light depends on the material, but can be as large as 10 dB or more. Therefore, since dripping photocurable resin into both gaps results in a large loss of resin curing light, it is preferable to drip photocurable resin into only one of the gaps. Details will be provided later.

Next, resin curing light 1_1, 1_2 is incident on each of the signal light input/output optical fibers 12_1, 12_2, and the resin curing light 1_1, 1_2 is emitted from the end face of each of the optical fibers 12_1, 12_2. This can be achieved, for example, by preparing an external semiconductor laser attached to a pigtail fiber and connecting the optical fiber attached to that light source to the signal light input/output optical fibers 12_1, 12_2 using an optical connector.

As a result, resin curing light 1_1 is emitted from the end face of one optical fiber 12_1, and resin curing light 1_2 is emitted from the end face of the second waveguide core 112_1 of the optical element 11 and irradiated onto the photocurable resin 14_1 (Figure 4).

As shown in Figure 5, the refractive index of the photocurable resin changes in the portions irradiated with resin curing light 1_1 and 1_2, causing the resin to harden and form a third waveguide core (SWW core) 131_1. As a result, a connection is made between the core of optical fiber 12_1 and the second waveguide core 112_1 of the optical element 11.

Here, resin curing light 1_1 is emitted from one of the signal light input/output optical fibers 12_1.

In addition, the resin curing light 1_2 emitted from the other signal light input/output optical fiber 12_2 is coupled from the end face of the other second waveguide core 112_2 and is emitted from the end face of one of the second waveguide cores 112_1 of the optical element 11.

In this way, it is possible to realize the emission of resin curing light 1_1 and 1_2 from both end faces of the waveguide core to be connected using only optical fibers 12_1 and 12_2 for inputting and outputting signal light, without using an optical fiber for inputting and outputting resin curing light, thereby realizing optical connection using SWW.

In addition, there is a gap between the end face of the other optical fiber 12_2 for inputting and outputting signal light and the second waveguide core 112_2. As a result, light emitted from the other optical fiber 12_2 for inputting and outputting signal light experiences diffraction loss when coupled to the second waveguide core 112_2.

However, (1) the intensity of the resin curing light required for the SWW can be low (for example, a few μW for a core diameter of approximately 3 μm thick and 3 μm wide, as used in this connection), (2) the diffraction loss is a few dB when assuming a gap of 100 μm used as the gap to form the SWW, and (3) the output of commercially available LDs is a few mW, which is more than an order of magnitude higher than the intensity (power) of the resin curing light required for the SWW, so it is possible to form a SWW even in the above-mentioned gap.

Next, photocurable resin is dripped into the gap between the other optical fiber 12_2 for inputting and outputting signal light and the second waveguide core 112_2 of the optical element 11, and resin curing light 1_1 and 1_2 are irradiated to form a third waveguide core (SWW core) 131_2 (Figure 6).

At this time, a third waveguide core (SWW core) 131_1 made of a photocurable resin that absorbs light of the curing wavelength is formed in the gap between one of the signal light input/output optical fibers 12_1 and the second waveguide core 112_1 of the optical element 11, but sufficient resin curing light 1_1 can be coupled into the other gap to form a third waveguide core (SWW core) 131_2.

This is because the SWW core of the cured photocurable resin has reduced absorption loss at the curing wavelength compared to the uncured state. This reduction in absorption loss is due to the reduction in the amount of polymerization initiator, which is the cause of absorption loss at the curing wavelength, as the resin cures. Polymerization initiators are contained in the curable resin and are activated by external factors such as light, causing the resin curing reaction.

In addition, since the diffraction loss is reduced by forming a third waveguide core (SWW core) 131_1 in the gap between one of the signal light input/output optical fibers 12_1 and the second waveguide core 112_1 of the optical element 11, sufficient resin curing light 1_1 can be coupled into the other gap to form a third waveguide core (SWW core) 131_2.

Finally, after forming the third waveguide cores 131_1 and 131_2, the third waveguide clads (SWW clads) 132_1 and 132_2 are formed around the third waveguide cores 131_1 and 131_2, thereby manufacturing the optical integrated device 10 shown in Figure 1.

For example, the uncured resin 142 around the third waveguide cores 131_1 and 131_2 is washed with an organic solvent such as ethanol, and then adhesive resin is dripped onto the cores and cured by light irradiation. This forms the third waveguide clads 132_1 and 132_2, and fixes the optical element 11 and the optical fibers 12_1 and 12_2.

Here, an example has been shown in which adhesive resin is used to form the third waveguide clads 132_1 and 132_2, but this is not limited to this. Any material that has a lower refractive index than the third waveguide cores (SWW cores) 131_1 and 131_2 and can be hardened can be used.

In this way, in the third waveguide, after the third waveguide cores 131_1 and 131_2 are formed, the third waveguide clads 132_1 and 132_2 are formed by a method (resin replacement method) in which the uncured portions 142 around the third waveguide cores 131_1 and 131_2 are removed and replaced with another material such as resin.

The third waveguide clads 132_1 and 132_2 may be formed not only by the resin replacement method, but also by using two types of resin, as shown below.

In this case, first, a resin that hardens at a first wavelength (λ1) and a resin that hardens at a second wavelength (λ2) are mixed, and the mixed resin is then dripped into the gap between one of the optical fibers 12_1 for inputting and outputting signal light and the second waveguide core 112_1 of the optical element 11.

Next, the resin that hardens at a wavelength of λ1 is hardened by the first resin hardening light (wavelength λ1) emitted from the end face of the waveguide core to form third waveguide cores (SWW cores) 131_1 and 131_2.

Finally, the uncured portions, i.e., the portions of the resin that are cured at a wavelength of λ2, are cured by irradiating them with a second resin curing light (wavelength λ2) from the outside (around the SWW) to form the third waveguide clads 132_1 and 132_2.

In this way, the third waveguide clads 132_1 and 132_2 can be formed by using two types of resin.

Here, we have shown an example of forming a third waveguide clad, but this is not limiting, and the optical integrated element can operate even if the third waveguide is composed of only a third waveguide core.

The connecting waveguide 115 can have any shape. For example, as shown in Figure 7, a curved waveguide core and a straight waveguide core may be combined to connect two adjacent optical multiplexing/demultiplexing sections 114_1 and 114_2. The width of the waveguide cores connecting the optical multiplexing/demultiplexing sections 114_1 and 114_2 need only be such that they function as waveguides in the resin curing light.

Furthermore, as shown in Figure 8, the structure of the optical integrated element 10_3 in this embodiment can be made multi-core by connecting any number (N sets) of second waveguide cores 112_1, 112_2 of the optical element 11 connected to two optical fibers 12_1, 12_2 using optical connection parts 13_1 to 13_N using a SWW.

In this embodiment, light with a wavelength of 405 nm, for example, can be used as the resin curing light for forming the SWW. This is not limited to this, and light with a wavelength of 350 nm or more can also be used, as long as it has a wavelength that can change the refractive index of the SWW material and harden it.

The medium used as the SWW is not limited to photocurable resin; any material that undergoes a light-induced change in refractive index can be used. For example, the waveguide core can be formed using a solid resin or crystalline material that exhibits an increase in refractive index due to photoreaction.

In addition, the waveguide structure (circuit structure) including the upper cladding and lower cladding in the optical element is formed on a substrate. However, this is not limited to this, and the waveguide structure does not have to be formed on a substrate, but may be embedded in a material such as glass.

In addition, in this embodiment, an example has been shown in which the optical element is configured with a waveguide structure in which the second waveguide core covers the first waveguide core, but this is not limited to this. As shown in Figure 9, a configuration in which the second waveguide core does not have a waveguide structure at the base end side of the first waveguide core, and a layered structure 116 is laminated on the first waveguide core, is also possible.

First Example
A method for manufacturing the optical element 11 and the integrated optical element 10 according to the first embodiment of the present invention will be described.

First, the optical element 11 according to this embodiment is manufactured. First, the material for the lower cladding is deposited on a substrate, and then the material for the first waveguide cores 111_1 and 111_2 is deposited on top of that. In this case, the substrate is made of Si, the lower cladding is made of SiO2, and the first waveguide cores 111_1 and 111_2 are made of Si or the like.

Next, photolithography is used to process the Si into first waveguide cores 111_1 and 111_2.

Next, the material of the second waveguide cores 112_1 and 112_2, such as SiON, is laminated on the first waveguide cores 111_1 and 111_2. SiON can be formed by adding nitrogen when depositing silicon oxide.

Next, the SiON is processed into second waveguide cores 112_1 and 112_2 using conventional photolithography.

Finally, the upper cladding section 110 is formed using a material such as silicon oxide so as to cover the second waveguide cores 112_1 and 112_2. This completes the manufacturing process of the optical element 11 according to the embodiment of the present invention.

Next, an optical integrated element 10 is manufactured using an optical element 11 according to an embodiment of the present invention.

First, a SWW material, such as a photocurable resin, is dripped (placed) on the end face of the second waveguide core 112_1 of the aforementioned optical connection element.

Next, in the process described above, resin curing light 1_1, 1_2 is propagated through the second waveguide cores 112_1, 112_2, and the photocurable resin is irradiated with the resin curing light 1_1, 1_2 to photo-cure it, thereby forming third waveguide cores (SWW cores) 131_1, 131_2.

Next, for example, the portions 142 of the photocurable resin that were not irradiated with the resin curing light 1_1 and 1_2 and therefore not cured are removed by cleaning or the like.

Finally, the photocured photocurable resin, i.e., the resin is dripped (placed) around the third waveguide cores (SWW cores) 131_1 and 131_2 to form third waveguide clads 132_1 and 132_2.

Second Embodiment
An optical element and an optical integrated element according to a second embodiment of the present invention will be described with reference to FIGS.

<Configuration of optical integrated device>
10, an optical integrated device 20 according to this embodiment includes an optical device 21, optical fibers 12_1 and 12_2, and optical connecting portions 13_1 and 13_2. In the optical integrated device 20, the optical fibers 12_1 and 12_2 for inputting and outputting signal light are arranged in V-grooves 211_1 and 211_2.

The optical element 21 has a configuration similar to that of the first embodiment on a substrate 210. V-grooves 211_1 and 211_2 are formed in the substrate 210 so that the end faces of the optical fibers 12_1 and 12_2 for inputting and outputting signal light can be positioned opposite the end faces of the second waveguide cores 112_1 and 112_2.

Here, for example, V-grooves 211_1 and 211_2 are formed by anisotropic etching using a Si substrate on substrate 210. Because V-grooves 211_1 and 211_2 are formed using a semiconductor wafer process, they can be positioned with high precision relative to the optical fibers for inputting and outputting signal light.

<Method of manufacturing an optical integrated device>
A method for manufacturing the integrated optical device 20 according to this embodiment will be described.

First, photocurable resin is dripped into the V-grooves 211_1 and 211_2 to adhesively fix the optical fibers 12_1 and 12_2.

Next, the two optical fibers 12_1 and 12_2 for inputting and outputting signal light are placed in the V-grooves 211_1 and 211_2, respectively. As a result, the photocurable resin penetrates and fills the gap between the optical fibers 12_1 and 12_2 and the V-grooves 211_1 and 211_2.

Here, it is preferable to press the optical fibers 12_1 and 12_2 for inputting and outputting signal light from above using a glass lid 22 or the like so that the optical fibers 12_1 and 12_2 for inputting and outputting signal light are positioned in the V-grooves 211_1 and 211_2 with high precision.

Next, the resin used to adhesively fix the optical fibers is cured by irradiating it with UV lamp light, adhesively fixing the V-grooves 211_1 and 211_2 to the optical fibers 12_1 and 12_2. At this time, the glass lid 22 may also be fixed with adhesive in the same way.

Next, photocurable resin is dripped into the gap between one of the signal light input/output optical fibers 12_1, 12_2 and the second waveguide core 112_1 of the optical element 21. In this case, as in the first embodiment, it is preferable to drip the photocurable resin into only one of the gaps.

Next, resin curing light 1_1, 1_2 is incident on each of the signal light input/output optical fibers 12_1, 12_2, and the resin curing light 1_1, 1_2 is emitted from the end face of each of the optical fibers 12_1, 12_2. As a result, as in the first embodiment, a third waveguide core (SWW core) 131_1 is formed in the gap between one of the signal light input/output optical fibers 12_1 and the second waveguide core 112_1 of the optical element 21.

Next, resin is dripped into the gap between the other signal light input/output optical fiber 12_2 and the second waveguide core 112_2 of the optical element 21, and resin curing light 1_1, 1_2 is emitted from the end faces of the signal light input/output optical fibers 12_1, 12_2. This forms a third waveguide core (SWW core) 131_2 in the gap between the other signal light input/output optical fiber 12_2 and the second waveguide core 112_2 of the optical element 21.

Finally, as in the first embodiment, the third waveguide clads 132_1 and 132_2 are formed by replacing the uncured resin with another adhesive resin as appropriate and curing it.

In this embodiment, an example is shown in which the SWW is formed after the optical fiber is fixed, but this is not limited to this; the optical fiber may be fixed after the SWW is formed. Furthermore, the resin that forms the SWW may be used directly to bond the optical fiber to the V-groove.

In addition, while this embodiment shows an example in which a glass lid is used, the same effect can be achieved regardless of the lid material. For example, a lid made of a polymer material may be used. Also, while an example in which the glass lid is fixed is shown, it may be removed without being fixed. For example, the lid may be removed in the final process before the resin for the SWW is replaced.

11, a resin evacuation groove 212_1 may be formed between adjacent V-grooves 211_1 and 211_2. This has the effect of preventing resin from penetrating into the gap between the optical fiber 12_2 for inputting and outputting signal light and the second waveguide core 112_2 of the optical element 21 when forming a third waveguide core (SWW core) 131_1 in the gap between the optical fiber 12_1 for inputting and outputting signal light and the second waveguide core 112_1 of the optical element 21.

In this embodiment, unlike the first embodiment, adjacent optical fibers 12_1 and 12_2 for inputting and outputting signal light are arranged on the same substrate 210 without any space between them. Therefore, for example, when V-grooves 211_1 and 211_2 are filled with resin, or when one optical fiber 12_1 is arranged in V-groove 211_1 and 211_2, the resin that overflows from V-groove 211_1 penetrates into the gap between the other optical fiber 12_2 for inputting and outputting signal light and the second waveguide core 112_2 of the optical element 21.

Therefore, by forming a groove (resin evacuation groove) 212_1 for evacuating the resin between adjacent V-grooves 211_1 and 211_2, the unintended penetration of resin as described above can be prevented. Here, resin evacuation groove 212_1 can be easily formed using anisotropic etching, just like V-grooves 211_1 and 211_2.

In addition, in this embodiment, a multi-core connection configuration can be achieved, for example, as shown in Figure 12.

Third Embodiment
An optical element and an optical integrated element according to a third embodiment of the present invention will be described with reference to FIGS.

<Configuration of optical integrated device>
As shown in FIG. 13, an optical integrated device 30 according to this embodiment has a configuration in which an optical device 11 and an optical fiber array 31 are connected via optical connecting portions 13_1 and 13_2.

In the optical integrated device 30, the connection side of the optical fibers 32_1 and 32_2 for inputting and outputting signal light is made into an optical fiber array. The other configurations are the same as those of the first and second embodiments.

This optical fiber array configuration increases the bonding area between the optical element 11 and the optical fibers 32_1 and 32_2 for inputting and outputting signal light. Furthermore, the optical fibers 32_1 and 32_2 for inputting and outputting signal light can be easily fixed to an alignment jig.

Also, in the optical integrated element 30_2, as shown in Figure 14, a resin evacuation groove 33_1 may be formed between adjacent optical fibers 32_1, 32_2 in the optical fiber array 31. This has the effect of preventing resin from penetrating into the gap between the other signal light input/output optical fiber 32_2 and the second waveguide core 112_2 of the optical element 11 when connecting one signal light input/output optical fiber 32_1 and the second waveguide core 112_1 of the optical element 11 using the optical connection section 13_1 by SWW.

The resin evacuation groove 33_1 in the optical fiber array 31 can be produced, for example, by mechanically processing the end face of the optical fiber array 31 for signal light input/output after it has been produced, using dicing or other methods.

In addition, in this embodiment, by increasing the number of cores as shown in Figure 15, it is possible to connect multiple cores at once.

<Fourth embodiment>
An optical element and an optical integrated element according to a fourth embodiment of the present invention will be described with reference to FIGS.

<Configuration of optical integrated device>
As shown in FIG. 16, an optical integrated device 40 according to this embodiment includes an optical device 41, optical fibers 12_1 and 12_2, and optical connecting portions 13_1 and 13_2.

The optical integrated device 40 comprises two connecting waveguides 115, 415 and two sets of optical multiplexing/demultiplexing units (first optical multiplexing/demultiplexing units 114_1, 114_2, second optical multiplexing/demultiplexing units 414_1, 414_2). The other configurations are the same as those of the first embodiment.

For example, in the first embodiment, as shown in Figure 17, resin curing light 1_2 incident from the end face of the optical element 11 to the other second waveguide core 112_2 reaches the optical multiplexing/demultiplexing section 114_2, branches into the connecting waveguide 115, propagates, and is then emitted from the end face of one of the second waveguide cores 112_1. On the other hand, a portion of the incident resin curing light 1_2 does not branch into the connecting waveguide 115, but is coupled to the waveguide in the straight direction of the second waveguide core 112_2.

The resin curing light 1_2 incident on the optical element 11 that couples in the straight direction does not couple to one of the second waveguide cores 112_1 and does not contribute to the formation of the third waveguide core (SWW core) 131_1. As a result, the coupling efficiency of the resin curing light 1_2 to one of the second waveguide cores 112_1 decreases, resulting in a loss in the resin curing light 1_2.

Here, if the SWW core can be formed with low light intensity, optical connection using the SWW can be sufficiently performed even if there is loss in the resin curing light as described above. On the other hand, if the SWW core is formed using a resin that has low sensitivity to the resin curing light, for example, if the longitudinal length of the SWW is limited by the material's absorption of the resin curing light, a high intensity of the resin curing light is required.

Therefore, when connecting long gaps with SWW, the SWW core is formed with a wavelength that is insensitive to the resin but can cause a resin curing reaction. In this case, light that is insensitive to the resin curing light is used, so resin curing light with high light intensity is required.

As a result, as shown in Figure 17, if resin curing light 1_2 is coupled in a path that does not contribute to the formation of SWW core 131_1, i.e., in a straight direction, causing loss, resin curing light 1_2 cannot be coupled with sufficient intensity from the desired end face.

As shown in Figure 16, the optical integrated element 40 has two connecting waveguides 115, 415 connected via two stages (two sets) of Y-branch shaped optical multiplexing/demultiplexing sections (first optical multiplexing/demultiplexing sections 114_1, 114_2, second optical multiplexing/demultiplexing sections 414_1, 414_2).

As a result, for example, of the resin curing light 1_2 incident on the other second waveguide core 112_2, the light that is coupled in a straight direction by the other first optical multiplexing/demultiplexing section 114_2 can be propagated through the connecting waveguide 415 via the other second optical multiplexing/demultiplexing section 414_2 and coupled to one second waveguide core 112_1 via one second optical multiplexing/demultiplexing section 414_1.

Therefore, the loss in the above-mentioned resin curing light 1_2 can be reduced, and the actual coupling efficiency of the resin curing light in forming the third waveguide core (SWW core) 131_1 can be improved.

In addition, while this embodiment shows an example with a two-stage optical multiplexer/demultiplexer and two connecting waveguides, it is also possible to provide multiple stages of optical multiplexers/demultiplexers and multiple connecting waveguides. This will depend on the absorption loss due to the material that makes up the waveguide and the scattering loss due to the waveguide, but it is possible to improve the coupling efficiency to the second waveguide core that contributes to the formation of the SWW core.

Fifth Embodiment
An optical element and an optical integrated element according to a fifth embodiment of the present invention will be described with reference to FIGS. 18A and 18B.

<Configuration of optical integrated device>
As shown in FIG. 18A, an optical integrated device 50 according to this embodiment includes an optical device 51, optical fibers 12_1 and 12_2, and optical connecting portions 13_1 and 13_2.

In the optical element 51, the optical multiplexing/demultiplexing units 514_1 and 514_2 are configured with optical switches. For example, as shown in FIG. 18A, heaters 52_1 and 52_2 made of metal thin-film electrodes are integrated near the second waveguide cores 112_1 and 112_2 in the linear direction proximal to the optical multiplexing/demultiplexing units 514_1 and 514_2.

By heating these heaters 52_1 and 52_2, the refractive index changes due to the thermo-optic effect, which changes the coupling efficiency for each waveguide branched in the optical multiplexing/demultiplexing units 514_1 and 514_2. As a result, the coupling efficiency of the resin curing light for the path (e.g., one of the second waveguide cores 112_1) that contributes to the formation of the third waveguide core (e.g., SWW core 131_1) can be improved.

In particular, the second waveguide cores 112_1 and 112_2, the upper cladding portion 110, and the lower cladding portion (not shown) are made of a polymer material whose refractive index decreases when heated. For example, as shown in Figure 18B, heater 52_2 is disposed near the waveguide in the straight direction of second waveguide core 112_2 in optical multiplexing/demultiplexing section 514_2 (hereinafter referred to as the "second waveguide core in the straight direction"). Heating with heater 52_2 decreases the refractive index of the second waveguide core in the straight direction.

As a result, the amount of resin curing light 1_2 that couples to the second waveguide core in the straight direction is reduced, and the resin curing light 1_2 branches into the connecting waveguide 115, propagates through the connecting waveguide 115, and is then emitted from the end face of one of the second waveguide cores 112_1, contributing to the formation of the third waveguide core (SWW core) 131_1. This improves the coupling efficiency of the resin curing light to the path that contributes to the SWW (one of the second waveguide cores 112_1).

In this embodiment, an example is shown in which an optical switch with a heater is used, but any structure that functions as an optical switch will do. For example, a Mach-Zehnder optical switch or an optical switch with a MEMS mirror may also be used.

In this way, by configuring the optical multiplexing/demultiplexing sections 514_1 and 514_2 in the optical element 51 using optical switches, the propagation direction of light can be switched, thereby improving the coupling efficiency of resin curing light to the path that contributes to the formation of the SWW core.

Sixth Embodiment
An optical element and an optical integrated element according to a fifth embodiment of the present invention will be described with reference to FIGS.

<Configuration of optical integrated device>
As shown in FIG. 19, an optical integrated device 60 according to this embodiment includes an optical device 61, optical fibers 12_1 and 12_2, and optical connecting portions 13_1 and 13_2.

The optical element 61 includes an optical function block 62 in a connecting waveguide 115 that connects adjacent waveguides. The other configurations of the optical integrated element 60 are the same as those of the first embodiment.

When forming a SWW core, if the resin curing light is irradiated with an appropriate intensity, the SWW core can be formed with a constant diameter. On the other hand, if the intensity of the resin curing light is higher or lower than the appropriate intensity, the SWW core will have a tapered shape.

Therefore, when forming third waveguide cores (SWW cores) 131_1 and 131_2 with a constant diameter using the optical function block 62, the intensity of the resin curing light can be adjusted to an appropriate intensity. Furthermore, by changing the intensity of the resin curing light using the optical function block 62, the third waveguide cores (SWW cores) 131_1 and 131_2 can be formed into a variety of shapes, such as a tapered shape.

Figure 20 shows an example of an optical function block 62 in which a Mazzoni modulator having a modulator electrode 63 is integrated as an optical switch in the connecting waveguide 115. The optical switch can control, for example, the intensity of the resin curing light from one second waveguide core 112_1 to the other second waveguide core 112_2.

The shape of the third waveguide cores (SWW cores) 131_1 and 131_2 changes depending on the intensity of the resin curing light. Therefore, the intensity of the resin curing light can be changed using an optical switch, allowing for precise control of the SWW formation conditions. Note that the optical switch may be anything other than a Mazzender modulator, as long as it functions as an optical switch.

Figure 21 shows an example of an optical function block 62 in which a groove 64 is provided in the connection waveguide 115. By inserting a specific optical function element into this groove 64, the resin curing light can be controlled. For example, by filling it with a resin that absorbs the resin curing light, the coupling strength of the resin curing light from one waveguide core to the other waveguide core can be controlled.

This allows the shape of the third waveguide cores (SWW cores) 131_1 and 131_2 to be controlled according to the intensity of the resin curing light.

Optical function blocks using grooves 64 can be applied even when it is difficult to integrate switches. Furthermore, if filling with resin, which has absorption losses, is not necessary, the effect of diffraction loss in the grooves 64 can be reduced by introducing a refractive index matching agent.

In the embodiment of the present invention, an example of a method for manufacturing an optical integrated device is shown in which a SWW material is placed in the gap between one second waveguide core and one optical fiber, resin curing light is applied to form one SWW core, and then a SWW material is placed in the gap between the other second waveguide core and the other optical fiber, resin curing light is applied to form the other SWW core. However, this is not limited to this. It is also possible to place a SWW material in the gap between one second waveguide core and the optical fiber and in the gap between the other second waveguide core and the optical fiber, and then irradiate resin curing light to form one SWW core and the other SWW core simultaneously.

In the embodiment of the present invention, an example is shown in which an optical fiber is used as the element to be connected to the optical element, but this is not limited to this and any element having an optical waveguide (optical waveguide element) can be used.

In the embodiments of the present invention, examples of the structure, dimensions, materials, etc. of each component in the configuration and manufacturing method of the optical element and optical integrated element are shown, but this is not limiting. Anything that can demonstrate the functions and effects of the optical element and optical integrated element will suffice.

The present invention relates to optical elements for connecting optical elements, optical integrated elements, and methods for manufacturing optical integrated elements, and can be applied to optical communication devices and optical communication network systems.

11 Optical element 111_1, 111_2 First waveguide core 112_1, 112_2 Second waveguide core 115 Connection waveguide 113_1, 113_2 Mode field conversion section 114_1, 114_2 Optical multiplexing/demultiplexing section 12 Optical waveguide element (optical fiber)
131_1, 131_2 third waveguide core

Claims (9)

An optical element connected to a set of optical waveguide elements via a set of third waveguide cores,
a set of first waveguide cores;
a set of second waveguide cores;
a connecting waveguide;
the refractive index of the first waveguide core is greater than the refractive index of the second waveguide core;
the first waveguide core has a mode field converting portion, and at least the mode field converting portion is covered by the second waveguide core;
the connecting waveguide connects the set of second waveguides via an optical multiplexing/demultiplexing section;
one of the second waveguide cores is connected to one of the optical waveguide elements at a predetermined end face of the optical element via one of the third waveguide cores;
the other second waveguide core is connected to the other optical waveguide element at the predetermined end face via the other third waveguide core,
the third waveguide core is a portion in which a refractive index is changed by irradiation of a set of resin curing light in a set of photocurable resin disposed in a gap between the set of optical waveguide elements and the set of second waveguide cores,
one of the resin curing lights is emitted from one of the optical waveguide elements and irradiated onto one of the photocurable resins arranged on the predetermined end face;
the other resin curing light is emitted from the other optical waveguide element, propagates through the other second waveguide core, the connecting waveguide, and the one of the second waveguide cores in order, is emitted from an end face of the one of the second waveguide cores at the predetermined end face, and is irradiated onto the one of the photocurable resins,
the other resin curing light is emitted from the other optical waveguide element and irradiated onto the other photocurable resin arranged on the predetermined end face,
the resin curing light is emitted from one of the optical waveguide elements, propagates in order through the one of the third waveguide cores, the one of the second waveguide cores, the connecting waveguide, and the other of the second waveguide cores, is emitted from an end face of the other of the second waveguide cores at the predetermined end face, and is irradiated onto the other of the photocurable resins. The optical element described in claim 1, characterized in that the optical multiplexing/demultiplexing section is provided closer to the base end of the second waveguide core than the mode field conversion section. The optical element according to claim 1 or 2, comprising a plurality of said connection waveguides. The optical element according to claim 1 , wherein the optical multiplexing/demultiplexing unit is configured by an optical switch. The optical element according to claim 1 , wherein the connecting waveguide comprises an optical function block. an optical element having a set of first waveguide cores, a set of second waveguide cores, and a connecting waveguide;
a pair of optical waveguide elements for inputting and outputting optical communication signals;
a set of optical connections having a third waveguide core;
one of the second waveguide cores and one of the optical waveguide elements are connected at a predetermined end face of the optical element via the third waveguide core of one of the optical connection parts;
the other second waveguide core and the other optical waveguide element are connected at the predetermined end face via the third waveguide core of the other optical connecting portion,
the first waveguide core has a mode field conversion portion and is covered by the second waveguide core;
the connecting waveguide connects the set of second waveguides via an optical multiplexing/demultiplexing section;
the third waveguide core is a portion in which a refractive index is changed by irradiation of a set of resin curing light in a set of photocurable resin disposed in a gap between the set of optical waveguide elements and the set of second waveguide cores,
one of the resin curing lights is emitted from one of the optical waveguide elements and irradiated onto one of the photocurable resins arranged on the predetermined end face;
the other resin curing light is emitted from the other optical waveguide element, propagates through the other second waveguide core, the connecting waveguide, and the one of the second waveguide cores in order, is emitted from an end face of the one of the second waveguide cores at the predetermined end face, and is irradiated onto the one of the photocurable resins,
the other resin curing light is emitted from the other optical waveguide element and irradiated onto the other photocurable resin arranged on the predetermined end face,
the resin curing light is emitted from one of the optical waveguide elements, propagates in order through the third waveguide core of the one of the optical connection parts, the second waveguide core of the one of the optical waveguide elements, the connecting waveguide, and the second waveguide core of the other of the optical integrated elements, is emitted from an end face of the second waveguide core of the other of the optical integrated elements at the predetermined end face, and is irradiated onto the photocurable resin of the other of the optical integrated elements. the optical element comprises a substrate;
7. The optical integrated device according to claim 6, wherein the set of optical waveguide elements is disposed in a V-groove in the substrate. 8. The optical integrated element according to claim 6, further comprising a resin escape groove provided between the pair of optical waveguide elements. a step of arranging an end face of an optical element having a set of first waveguide cores, a set of second waveguide cores, and a connecting waveguide connecting the set of second waveguide cores, so as to face an end face of the set of optical waveguide elements;
a step of aligning a center of the second waveguide core with a center of the optical waveguide element;
a step of disposing one photocurable resin in a gap between an end face of one of the second waveguide cores at the end face of the optical element and an end face of one of the optical waveguide elements;
a step of disposing another photocurable resin in a gap between an end face of the other second waveguide core at the end face of the optical element and an end face of the other optical waveguide element;
a step of irradiating one of the resin curing lights onto the one of the optical waveguide elements and irradiating the one of the photocurable resins to at least partially form one of the self-forming waveguides;
a step of making the other resin curing light incident on the other optical waveguide element, propagating sequentially through the other second waveguide core, the connecting waveguide, and the one second waveguide core, and outputting the light from an end face of the one second waveguide core to irradiate the one photocurable resin, thereby at least partially forming the one self-forming waveguide;
a step of irradiating the other resin curing light onto the other optical waveguide element and the other photocurable resin, thereby at least partially forming the other self-forming waveguide;
a step of causing the one of the resin curing light to be incident on the one of the optical waveguide elements, to propagate through the one of the self-forming waveguides, the one of the second waveguide cores, the connecting waveguide, and the other of the second waveguide cores, to emit the resin curing light from an end face of the other of the second waveguide cores, and to irradiate the other of the photo-curable resins, thereby at least partially forming the other of the self-forming waveguides.