JP2581089B2 - Method for manufacturing optical integrated circuit having mask - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing an optical integrated circuit having a mask.

2. Description of the Related Art With the recent development of optoelectronics, optical transmission systems tend to be widely used as alternatives to conventional telecommunication systems. This optical transmission system uses an optical fiber made of, for example, quartz or multi-component glass as a medium for transmitting information by light, so that it is free from electromagnetic dielectric interference and has a large information transmission density. It has many advantages, including: In the above-described optical transmission technology, the optical fiber is coupled to a substrate of an optical integrated circuit in which a light emitting element, a waveguide, a light receiving element, and the like are integrated, and optical information is exchanged between the optical waveguide of the substrate and the optical fiber. (Light incidence / emission).

Problems to be Solved by the Invention As means for inputting and outputting light between an optical waveguide of an optical integrated circuit board and an optical system such as an optical fiber, the following forms are generally known.

As shown in FIG. 3, a groove 12 having a required depth which is opened at an end 10a of the optical integrated circuit board 10 is formed on the surface of the optical integrated circuit board 10, and the tip of the optical fiber 14 faces the groove 12. A bonding method in which the two are bonded with an ultraviolet curing resin or the like. According to this coupling method, the core 14a at the tip of the optical fiber 14 is
There is an advantage that positioning can be performed with high precision at the end 18a of the optical waveguide 18 located at the innermost part of the groove 12. However, on the other hand, since the substrate 10 is made of a highly brittle and difficult-to-cut material such as glass material or lithium niobate, the processing of the groove 12 is generally difficult, and cracks and chips are generated during the processing, resulting in a failure rate. Has the disadvantage of being high.

As shown in FIG. 4, the light from the optical fiber 14 is focused by a condenser lens 16 and the focused light is
A method of making the light incident on the polished end face 18a in 18. This method has drawbacks in that, since the condensing lens 16 is used, the configuration is large, the manufacturing cost is increased, and optical axis alignment is difficult.

As shown in FIG. 5, a rutile prism 20 made of titanium oxide (TiO ₂ ) is attached to the optical waveguide 18 of the substrate 10, and light enters the optical waveguide 18 via the rutile prism 20. A method of emitting light from the middle of the optical waveguide 18 through the prism 20. In this method, the rutile prism is expensive and uncommon, and has disadvantages such as protruding and bulky on the optical integrated circuit board and complicating the optical system.

A grating that produces a diffraction grating such as a Fresnel lens in an optical waveguide and reproduces a cylindrical wave by diffraction from an incident plane wave to achieve a lens function. This is disadvantageous in that the manufacturing process is complicated and expensive, and it depends on the wavelength of light, and it is difficult to align the optical axis.

As described above, various methods have been implemented as means for inputting and outputting light between the optical waveguide of the optical integrated circuit board and the optical system such as an optical fiber. However, since all of these methods have the above-described difficulties, a mask made of a material that is not affected by the laser beam is provided on the optical waveguide in the optical integrated circuit having the optical waveguide formed on the surface of the substrate.
It has been extremely difficult to manufacture an optical integrated circuit having a mask by irradiating a laser beam to a notch defined by a required pattern on the mask and subjecting the substrate and the optical waveguide to required groove processing.

SUMMARY OF THE INVENTION The present invention has been proposed in view of the drawbacks inherent in the conventional method of manufacturing an optical integrated circuit having a mask, and has been proposed to suitably solve the problem. On the optical waveguide formed on the surface of the circuit board, a mask made of a material that is not eroded by the laser beam is provided, and the mask is irradiated with a laser beam at a notch defined by a required pattern, so that the substrate and the optical waveguide have a required shape. It is an object of the present invention to provide a means for easily performing the groove processing when performing the groove processing.

Means for Solving the Problems In order to overcome the above problems and achieve the intended object, a method for manufacturing an optical integrated circuit having a mask according to the present invention is a method for manufacturing an optical integrated circuit having an optical waveguide formed on a surface of a substrate. On the optical waveguide, a mask made of a material that is not attacked by the laser beam is provided, and the mask is irradiated with a laser beam at a notch defined by a required pattern to perform a required groove processing on the substrate and the optical waveguide. A buffer functioning as a moderator for preventing attenuation of light energy passing through the optical waveguide is applied to the surface of the optical waveguide, and a cutout of the mask is provided with the buffer interposed between the optical waveguide and the mask. By irradiating a laser beam to the portion, a groove is formed in the substrate and the optical waveguide.

Embodiment Next, a method for manufacturing an optical integrated circuit having a mask according to the present invention will be described with reference to the accompanying drawings by way of a preferred embodiment. The same members as those already described with reference to FIG. 3 are designated by the same reference numerals.

The groove processing method according to the present invention uses a laser beam as the processing means. In the embodiment, a case where a CO ₂ laser having a wavelength of 10.6 μm is used will be described. As shown in FIG. 1, as an example, a buffer 21 is formed at a portion of the optical integrated circuit substrate 10 made of LiNbO ₃ to be processed.
Is applied, and a mask 22 made of a material that is not affected by the laser beam is formed on the buffer 21 in a desired pattern. That is, as will be described later, the buffer 21 includes a mask (which absorbs and attenuates light traveling through the optical waveguide) and the optical integrated circuit board 10.
Interposed between them and functions as a moderator for preventing the attenuation of light energy, and as the material, for example, SiO ₂ is preferably used. Applied. Aluminum oxide (Al ₂ O ₃ ) can also be used as the buffer 21.

As the mask 22, for example, a metal film having a thickness of about 15 μm made of aluminum (Al) is preferably used.
A thin film is formed on the buffer 21 of the substrate 10 by a resist method in a pattern in which a notch 22a having a size set to allow insertion of the tip of the optical fiber 14 is formed at an end of the mask 22. As the thin film forming method, a sputtering method, a vacuum evaporation method, or the like can be appropriately used as appropriate according to the size and material of the substrate 10.

The optical integrated circuit substrate 10 on which the mask 22 is formed in the required pattern as described above is placed on a known XY table (not shown), and by operating the table, the substrate 10 is moved in the X direction in plane coordinates. And in the Y direction. Above the movement area of the XY table, a processing head 24 of a CO ₂ gas laser processing machine (not shown) is located.

Next, the processing head 24 of the laser processing machine (not shown)
, A CO ₂ laser beam is emitted vertically downward, and the beam is applied to the mask 22 of the optical integrated circuit substrate 10. At the same time, the aforementioned XY table is operated, and the substrate 10
It is moved at desired timing in the direction and the Y direction. As a result, the laser beam relatively scans the mask 22, but the laser beam is reflected on the surface of the mask 22. Therefore, the portion of the optical integrated circuit substrate 10 covered by the mask 22 is not processed at all. However, when the laser beam scans a portion of the notch 22a opened in the mask 22, the beam instantaneously evaporates a beam irradiation site by its high energy. As a result, as shown in FIG. 2, the groove 12 is formed in the optical integrated circuit board 10 in accordance with the opening shape of the cutout 22a.
The processing conditions in this case are shown in Table 1 below.

The depth of the groove 12 is set to be larger than the diameter of the optical fiber 14 to be used by gradually increasing and changing the output of the laser processing machine. Adjust the position while transmitting light to 14. Also, even after the completion of the groove processing, the mask 22
Does not need to be removed from The reason is that the mask 22 made of a metal film absorbs light traveling through the optical waveguide of the optical integrated circuit substrate 10 to cause attenuation, but in this example, the substrate 10
This is because the interposition of the buffer 21 between the metal film mask 22 and the metal film mask suppresses the attenuation of light energy.

Next, the tip of the optical fiber 14 faces the obtained groove 12, and when the core 14a is directed to the end 18a of the optical waveguide 18, it is bonded and fixed with, for example, an ultraviolet curing resin. Although the illustrated example is for a three-dimensional optical waveguide, a similar groove processing method can be implemented for a two-dimensional optical waveguide.

Further, in the embodiment, an example in which the mask 22 made of a metal plate such as aluminum is formed on the substrate 10 has been described, but any material that reflects a laser beam and is not affected by this may be used.
Alternatively, the mask 22 may be made of gold (Au), silver (Ag), or the like. When a CO ₂ laser having a wavelength of 10.6 μm is used, the mask 22 may be formed of a thin film made of a material other than metal having a high reflectance with respect to the wavelength of 10.6 μm, for example, a ceramic film. Further, the optical integrated circuit board 10
May be fixedly positioned, and the processing head 24 may be moved in the X direction and the Y direction to perform laser beam processing.

Effect of the Invention As described above, a mask made of a material that is not affected by a laser beam is provided on an optical waveguide formed on the surface of an optical integrated circuit substrate, which is a brittle member. Conventionally, it has been difficult to irradiate a laser beam onto the substrate and perform the required groove processing on the substrate and the optical waveguide. However, according to the method of manufacturing an optical integrated circuit having a mask according to the present invention, a buffer functioning as a moderator for preventing attenuation of light energy passing through the optical waveguide is applied to the surface of the optical waveguide, and the optical waveguide and the mask are applied. By irradiating a laser beam to the notch of the mask with the buffer interposed between the substrate and the groove, the groove processing on the substrate and the optical waveguide can be easily performed. That is, since the buffer functioning as a buffer for preventing the attenuation of light energy is interposed between the optical waveguide of the substrate and the mask, it is not necessary to remove the mask even after the groove processing, and There is a great advantage that can be used in the state. Further, according to the method for processing a groove on a substrate, a laser beam applied to an optical integrated circuit substrate cannot attack the mask formed on the substrate at the portion of the mask, and the substrate can be exposed only through a notch of the mask. Can be eroded. Therefore, required groove processing on the substrate can be easily and rapidly performed. Further, since the mask is formed in a predetermined pattern on the groove processing planned portion on the substrate, there is an advantage that positioning of the groove processing is unnecessary unlike the case where the masking plate is mounted on the substrate.

[Brief description of the drawings]

FIG. 1 is an explanatory perspective view showing one embodiment in which a groove is formed in an optical integrated circuit substrate by the method according to the present invention, and FIG. 2 shows a state after the groove is formed by the method shown in FIG. FIG. 3 is a perspective view showing a coupling relationship between a groove of an optical integrated circuit substrate and an optical fiber, which is conventionally implemented, and FIG. FIG. 5 is a perspective view of a prior art in which light is incident and emitted using a rutile prism on an optical integrated circuit substrate. 10 ... substrate, 12 ... groove 14 ... optical fiber, 14 a ... core 16 ... condensing lens, 18 ... optical waveguide 18 a ... end, 20 ... rutile prism 21 ... buffer, 22 ... Mask 22a: Notch, 24: Processing head

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hikoharu Aoki 9-35, Horitadori, Mizuho-ku, Nagoya City, Aichi Prefecture Inside Brother Industries, Ltd. (56) References JP-A-58-34415 (JP, A) JP-A-59-202407 (JP, A) JP-A-69-195791 (JP, A) Japanese Utility Model Laid-Open No. 48-95563 (JP, U)

Claims (4)

(57) [Claims] 1. A mask (22) made of a material that is not affected by a laser beam is provided on an optical waveguide (18) in an optical integrated circuit having an optical waveguide (18) formed on the surface of a substrate (10). Notch (22) defined by the required pattern
a) irradiating a laser beam to the substrate (10) and the optical waveguide (18) to perform a required groove processing, and the surface of the optical waveguide (18) has a light energy passing through the optical waveguide (18). A buffer (21) functioning as a buffer for preventing attenuation is applied, and with the buffer (21) interposed between the optical waveguide (18) and the mask (22), the mask (22) is A method of manufacturing an optical integrated circuit having the mask, wherein a groove is formed in the substrate (10) and the optical waveguide (18) by irradiating the notch (22a) with a laser beam. 2. The method of manufacturing an optical integrated circuit having a mask according to claim 1, wherein said buffer (21) is made of SiO ₂ and applied to a portion of the substrate to be processed in a groove at a thickness of 1000 ° or more. 3. The method for manufacturing an optical integrated circuit having a mask according to claim 1, wherein said mask is a metal film selected from Au, Al, Cu and the like. Wherein said laser beam having a wavelength of 10.6 [mu] m CO ₂
2. The method for manufacturing an optical integrated circuit having a mask according to claim 1, wherein said mask is a thin film made of a material other than metal having a high reflectivity for a wavelength of 10.6 .mu.m.