JP3487219B2 - Optical module and manufacturing method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical module and a method of manufacturing the same, and more particularly, to an optical module having an optical waveguide for performing optical transmission between an optical fiber and an optical element and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, an optical module for WDM (wavelength division multiplexing) transmission / reception is a WDM for multiplexing / demultiplexing an optical signal of about 1.3 to 1.55 μm, as disclosed in Japanese Patent Laid-Open No. 10-160977. It has a circuit and a bidirectional optical transceiver circuit for transmitting and receiving an optical signal of about 1.3 μm. This optical transceiver circuit includes an optical waveguide having a lower clad layer, a core layer, and an upper clad layer, which are sequentially formed on a substrate. In this type of optical module, the core layer needs to have a thickness of about 10 μm, and the lower clad layer needs a thickness of 15 μm or more when the relative refractive index difference of the optical waveguide is about 0.45%.

In the above conventional optical module, the diameter is several μm.
A single mode optical fiber having a core of about m is installed and aligned. As a semiconductor laser device that supplies a light flux to a single-mode optical fiber, one having a spot size converter is usually used. For example, in the semiconductor laser device disclosed in Japanese Patent Laid-Open No. 8-234062, the spot diameter is set to about 10 μm which is almost the same as the diameter of the core of the single mode optical fiber as a result of the conversion.

In the case of a junction-down type semiconductor laser in which the active layer faces downward, the semiconductor laser is connected to a silicon terrace via a solder joint and mounted on an optical module. The electrical wiring of this semiconductor laser device is disclosed in JP-A-9-
As described in JP 61651, an electrode pattern is provided on the bottom surface of the cutout portion of the optical waveguide, and an optical element is mounted on this electrode pattern. When mounting a semiconductor laser device on an optical module, since high alignment accuracy is required, as described in JP-A-7-235566 and JP-A-10-170769, respectively, a self-alignment effect is obtained. It is used to satisfy the alignment accuracy.

In order to manufacture an optical module equipped with a semiconductor laser device at low cost, a polymer optical waveguide is used. This optical waveguide is configured, for example, as described in JP-A-6-273631. FIG. 7 is a side sectional view showing an outline of the optical module (first conventional example) described in the publication. In this optical module, a lower clad layer 39, a core layer 36, and an upper clad layer 37 are formed in this order on a silicon substrate 34, and the clad layer 37 is filled on the sides of the core layer 36 to form an optical waveguide. There is.
A resin material having a lower refractive index than the core layer 36 is used for the clad layer 37.

Further, in the optical module (second conventional example) described in Japanese Patent Application Laid-Open No. 9-281351, a core layer is formed on a transfer mold, a clad layer is applied on the core layer, and a clad layer and A clad layer is applied to a part of the core layer exposed by peeling the core layer from the transfer mold to form an optical waveguide. In both the first and second conventional examples, the optical waveguide includes a thin core layer having a substantially square cross section.

FIG. 8 is a plan view showing a conventional optical module (third conventional example) disclosed in Japanese Patent Laid-Open No. 10-148729. In this optical module, a strip line (core layer) 33 having a width e of about 10 μm is formed on a silicon substrate by the ridge pattern forming method.

[0008]

In the third conventional example, the strain 3 is generated on the side surface of the strip line 33 included in the optical waveguide.
2 is present or dust is mixed in the polymer resin of the strip line 33, light is scattered and good optical transmission is impaired. This phenomenon similarly occurs in the first and second conventional examples. For slab optical waveguides (planar optical waveguides) such as these, an optical system for converging light is required separately, but the process of inserting a planar lens as an optical system requires high positional accuracy of μ units at the insertion position. It is extremely difficult because it is done. Further, in the first conventional example, the refractive index difference between the core layer and the clad layer surrounding the core layer was small, and the angle at which light was reflected at the boundary surface between the core layer and the clad layer was limited.

In view of the above, the present invention improves the light reflection in the optical waveguide, eliminates the need to insert a plane lens for converging light, distorts the side surface of the core layer, and dust mixed in the core layer. An object of the present invention is to provide an optical module and a method for manufacturing the same that can reduce the influence of the above.

[0010]

In order to achieve the above object, an optical module of the present invention comprises an optical waveguide having a lower clad layer, a core layer and an upper clad layer, which are sequentially formed on a substrate. In an optical module that performs optical transmission between an optical fiber and an optical element via a core layer, the core layer has an edge part that forms a part of an ellipse in plan view, and the incidence of the optical fiber and the optical element It is characterized in that the mouth and the exit are respectively arranged at or near the two focal points of the elliptical shape.

In the optical module of the present invention, even if a light beam from an optical element (or an optical fiber) having an entrance port or an exit port disposed at one of two focal positions spreads in the optical waveguide, the light beam is directed to the core layer. It is possible to guide the light to the entrance port or the exit port of the optical fiber (or the optical element) at the other focal position while reflecting the light at the edge portion of. For this reason, it is possible to improve the light reflection at the edge of the core layer while eliminating the need for inserting a flat lens for converging light, distortion of the side surface of the core layer, dust mixed in the core layer, and the like. The effect of can be reduced.

Here, in the preferred optical module of the present invention, the ratio r / R of the minor axis r and the major axis R in the ellipse is:
The critical angle at which the light beam can be totally reflected at the edge is set to be smaller than a value expressed in radians. This allows
It is possible to obtain a reflecting surface in which total reflection is always good.

The method of manufacturing an optical module of the present invention is the method of manufacturing an optical module having an optical waveguide, wherein a lower clad layer is formed on a substrate, and a core layer and the core layer are formed on the lower clad layer. A side clad layer for partitioning is formed, the core layer is provided with an edge portion forming a part of an ellipse in a plan view, and the two focal points of the ellipse are respectively provided with an entrance of an optical fiber and an optical element. It is characterized in that an emission port is arranged.

In the method of manufacturing an optical module of the present invention, 2
While reflecting the light flux from the optical element (or optical fiber) in which the entrance or exit is arranged at one of the two focal positions at the edge of the core layer, the optical fiber (or optical element) at the other focal position An optical module leading to the entrance or exit is obtained. For this reason, it is possible to improve the light reflection at the edge of the core layer and reduce the influence of the side surface distortion of the core layer, etc., while eliminating the need for inserting a flat lens for converging light.

Here, in the method of manufacturing an optical module of the present invention, the core layer and the side clad layer are made of a light modifying material, and the core layer and the core layer are formed by changing the refractive index of the light modifying material by exposure. It is preferable to divide the side clad layer. This simplifies the manufacturing of the core layer and the side clad layer.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail based on the embodiments of the present invention with reference to the drawings. Figure 1
2 is a plan view showing a configuration of an optical module according to a first embodiment of the present invention, and FIG. 2 is a sectional view taken along line II-II in FIG.

The optical module 11A includes a silicon substrate 14
Has an optical fiber 12 at one edge, and has a light receiving element 15 and a light emitting element (laser diode) 16 with a spot size conversion function on both sides of the extension line of the optical fiber 12 at the other edge, Optical fiber 12 and light emitting element 1
6 or an optical waveguide for transmitting / receiving a light beam to / from the light receiving element 15.

The optical module 11A includes a silicon substrate 14
The installation location of the optical fiber 12 above is hydrofluoric acid, nitric acid,
Chemical etching is performed using an acidic aqueous solution such as sulfuric acid or acetic acid. The depth of the groove formed by chemical etching is such that when the single-mode optical fiber 12 having a diameter of about 125 μm is set on the silicon substrate 14, the core 13 becomes
The height is set to about 30 μm from the surface of the.

The light-emitting element 16 and the light-receiving element 1 exposed previously
Wiring patterns 17 and 18 are formed in the mounting region of No. 5. Each of the wiring patterns 17 and 18 is formed of a copper plating pattern having a thickness of about 4 μm, and is a minute ball grid array (ball grid array: about 26 μm) fixed to the lower surface of the formed light emitting element 16 and the light receiving element 15. BGA) 23 is connected to the component terminal.

Next, a wall of synthetic resin having a height of about 30 μm is formed around the silicon substrate 14 to form a platform, and the components are adjusted in this platform so that the refractive index after curing becomes about 1.50. The liquid mixture of the liquid epoxy oligomer and the photopolymerization initiator is filled. After injecting the mixed solution, an ultraviolet mask is placed on the platform, and ultraviolet rays are radiated from the ultraviolet mask to cure the liquid epoxy oligomer of the mixed solution according to the pattern of the ultraviolet mask.

The ultraviolet mask has a pattern that covers the mounting area of the light emitting element 16 and the light receiving element 15 each having a square shape with one side of about 1 mm and the installation area of the optical fiber 12. The mounting areas of the masked light emitting element 16 and the light receiving element 15 are
The oligomer is removed by developing with an isopropanol solution to form a pattern of the lower cladding layer 26.

Then, a polymer solution of the photo-modifying material 24 of the nobornagen structure having a refractive index of 1.57 is applied on the lower clad layer 26 by spin coating to a thickness of about 10 μm, and vacuum dried at room temperature to form a thin film. Is formed as a core layer. Then, the core layer is subjected to an ultraviolet mask having a predetermined shape, and ultraviolet rays are irradiated along the two ellipses shown in FIG. 1 by using a high pressure mercury lamp, and the refractive index of the region outside the ellipse is 0.01. The side cladding layer 20 is reduced to some extent.
As a result, an optical waveguide including the elliptical core layers 19a and 19b is formed.

Further, like the lower clad layer 26, an ultraviolet curable epoxy resin having a refractive index of 1.50 is applied to the core layers 19a and 19b and the side clad layer 20 to a thickness of about 30 μm. After that, the light emitting element 16 and the light receiving element 15
While shielding the mounting area of with a UV mask of a predetermined shape, irradiate UV to cure the UV curable epoxy resin,
The uncured portion is removed by developing with an isopropanol solution to form the upper clad layer 28.

Next, the thin film of the photo-modifying material 24 exposed from the removed portion of the upper clad layer 28 and not forming the core layers 19a and 19b is dissolved in chloroform and removed. The silicon substrate 14 and the wiring patterns 17 and 18 in the mounting regions of the light emitting element 16 and the light receiving element 15 are exposed, and the BGAs 23 on the lower surfaces of the light emitting element 16 and the light receiving element 15 are connected to the wiring patterns 17 and 18, respectively.

At this time, the light emitting element 16 and the light receiving element 15
Is aligned with the copper patterns of the wiring patterns 17 and 18 by self-alignment, and the entrance of the light receiving element 15 and the exit of the light emitting element 16 are accurately opposed to the optical waveguides 19a and 19b, respectively. The optical waveguide (19a) and the optical waveguide (19
In the groove part whose plane shape intersects with b) is substantially V-shaped,
The optical fiber 12 is provided at each of the focal points on both sides of the optical waveguide.
Align the core 13 of.

Although the silicon substrate 14 is used in the present embodiment, the substrate is not limited to this, and a metal substrate coated with an insulating resin, a ceramic substrate, a glass substrate, or an organic resin substrate can be used. Thus, an optical module similar to the above can be manufactured.

Further, the optical waveguides (19a, 19b) can be formed by the following steps without using the photo-modifying material 24 having the nobornagen structure of this embodiment. First, a polyimide precursor solution is filled on the lower clad layer 26, and the precursor solution is about 70 ° C. for 2 hours, about 160 ° C. for 1 hour, about 250 ° C. for 30 minutes, and about 350 ° C. for 1 hour. Each is heat treated to form a polyimide.

Further, with the X-ray mask pattern provided on the polyimide, the peak energy is about 100 eV.
Is exposed to X-rays to form a pattern of the core layer of the optical waveguide having an increased refractive index in polyimide, and an alkali-resistant resist is applied on this pattern. After forming a resist pattern by transferring the mask pattern to this resist, the polyimide resin at the installation positions of the light emitting element 16 and the light receiving element 15 and the optical fiber installation position is removed by alkali etching.

The overall shape of the optical waveguide is such that each elliptical region (core layers 19a, 19b) having a major axis R of about 10 mm and a minor axis r of about 0.4 mm has both major axes R of about 12 mm. They intersect each other at an angle to form a substantially V-shape, and the apex 22a of this substantially V-shape region faces the end of the core 13 of the optical fiber 12. The side cladding layer 20 has a refractive index of the core layers 19a, 19
It is reduced by about 0.01 for each refractive index of b. Abbreviation V
The light emitting element 16 has an end opposite to the apex 22a in the character shape.
Of the light receiving element 15 and the light receiving element 15 are opened.

The light receiving element 15 and the light emitting element 16 are located at the focal points of the other of the elliptical core layers 19a and 19b.
Arrange each opening of about 10 μm. As a result, the laser light flux can be guided from the light emitting element 16 to the core 13 having a diameter of about 10 μm and from the core 13 to the light receiving element 15.

Here, assuming that the diameter of the core end of the optical fiber 12 is d, the spread angle (half angle) of the light emitted from the core end is calculated as (4 / π) × λ / d [rad]. To be done. That is, when light with a wavelength λ of about 1.3 μm is emitted from the core 13 of the optical fiber 12 with a diameter d of about 10 μm and is incident on the slab optical waveguide, the spread angle of the incident light is 0.17 [rad] (= 9.7 degrees). The apex 22a of the substantially V-shaped region is provided at a position approximately 1 mm from the core 13, and the light is totally reflected in the substantially V-shaped region and directed toward the light emitting element 16 and the light receiving element 15.

If the major axis (major axis) of the elliptical core layers 19a and 19b is sufficiently larger than the minor axis (minor axis),
The light emitted from one of the focal points comes into contact with the boundary forming a part of the ellipse at the position of the distance Z from this focal point,
Total reflection occurs if the following conditions are met. That is, when the core layers 19a and 19b have a refractive index of N and the cladding layer 20 on the side surface has a refractive index of n, the boundary surface and the incident angle are equal to or smaller than the angle ω calculated by the following equation (1). The light is totally reflected. ω = (π / 2) -Arcsin (n / N) [rad] …… (1)

In this embodiment, the core layers 19a and 19b are used.
Refractive index N (= 1.57) of the clad layer 20,
Since (= 1.56), the following formula (2) is calculated,
ω = 0.11 [rad] (= 6.5 degrees). Light incident on the ellipsoid at an angle less than this angle is totally reflected, but light incident at an angle exceeding this angle cannot be totally reflected. h = {r / (2 × R)} × (2 × R × Z−Z ² ) ^0.5 (2)

On the other hand, the angle (θ) formed by the light incident on the reflecting surface whose planar shape is part of an ellipse and the reflecting surface can be approximately calculated by the following equation (3). θ = h × [(1 / Z) + {1 / (2 × R−Z)}] (3) where h is the height of the ellipse, r is the radius of the ellipse on the short axis, and R is It is the radius of the major axis of the ellipse.

In order to perform total reflection at the boundary of the elliptical region, it is necessary that the angle θ is smaller than the critical angle ω of total reflection. To make the angle θ equal to or smaller than ω, in the case of a slender ellipse, the position where the light enters the ellipse (distance from the emitted focus) Z and the ellipse are calculated by the following equations (4) to (6). It is necessary that the distance Δ with respect to the focal point of approximately satisfies Expression (7) below. Δ = Z / R (4) Δ1 = 1- [1-{(r / R) / ω} ² ] ^0.5 (5) Δ2 = 1 + [1-{(r / R) / ω} ² ] ^0.5 (6) Δ1 <Δ <Δ2 (7)

The ratio r / R of the minor axis r and the major axis R is greater than the value expressed in radians as the critical angle ω at which the light ray can be totally reflected at the angle θ formed by the boundary line of the side cladding layer and the light ray. It is necessary to form a small elongated elliptical core layer. Therefore, in order to allow the solution of equation (7) to exist, the elliptical minor axis r
(R / R) is smaller than ω. In the present embodiment, since ω = 0.11 [rad], in order for this solution to exist, the ratio (R / r) of the major axis R and the minor axis r of the ellipse is (1 / ω) = It must be greater than 9.

In this embodiment, R = 5 mm, r = 0.
The length R is set to 2 mm, and the major axis R is 25 times the minor axis r. When the equation (6) is calculated under this condition, and the conditional equation for Z is calculated by substituting the equation (3), the following equation (8) is obtained. 0.35mm <Z <9.65mm (8)

In this way, the major axis of this embodiment is 10 mm.
If it is outside the range of 0.35 mm from both ends of the ellipse of
Total reflection is possible at any position of the ellipse. In this elliptical shape, the distance between the two focal points and the elliptical end is about 4 μm, which is extremely close to each other.
There is substantially no difference between the case of arranging the aperture No. 5 and the case of arranging it at the focal position.

The light emitted from the optical fiber 12 has a spread radius of 0.17 / 2 = 1 mm away from the optical fiber 12.
0.085 mm, but about 1 m from the focal point on the exit side
When the height at the position m ahead is calculated by substituting the distance Z = 1 mm from the focus into the equation (2), h = 0.12 mm is obtained, and the entire luminous flux spread to a radius of 0.085 mm is It can be seen that it can be surrounded by an ellipse.

Since the distance A between the apex 22a of the substantially V-shaped region and the end of the core 13 is about 1 mm, the exit of the light emitting element 16 and the entrance of the light receiving element 15 are about 9 mm from the apex 22a.
It is located at the rear, and is vertically separated from the optical axis O by about 1.9 mm. Approximately 10 μ at each rear end of the core layers 19a and 19b
m openings are formed, and each of the openings is connected to the emission port and the incident port of the light emitting element 16 and the light receiving element 15 of about 1 mm square. Thereby, an optical signal can be transmitted between the core 13 of the optical fiber 12, the light emitting element 16, and the light receiving element 15 via the optical waveguides (19a, 19b).

Next, a second embodiment of the present invention will be described. FIG. 3 is a plan view showing the optical module of this embodiment. The optical module 11B has two elliptical regions (19a, 19b) having a major axis length R of about 10 mm and a minor axis length r of about 0.6 mm, and one end of the optical fiber 1B.
It is assumed that the second core 13 faces the opening. Further, the optical axes O of the emitted light are inclined in opposite directions by 10 degrees, the intersections of the core layers 19a and 19b are apexes 22b, and one edge of the core layers 19a and 19b is a boundary surface. The letter-shaped region 27 is formed.

Using the formulas (4) and (7) in the first embodiment, a region where the light flux connecting the respective focal points in both the core layers 19a and 19b can be totally reflected by each reflecting surface in the elliptical region is used. By calculation, the following equation (9) is obtained. 0.81mm <Z <9.19mm (9)

The apex 22b of the substantially V-shaped region 27 is the intersection of the elliptical regions, and this intersection is about 1 mm away from the exit of the optical fiber 12. This position is expressed by equation (9).
Since it is within the range, the light incident on the substantially V-shaped region 27 is totally reflected at this position.

The shape of the substantially V-shaped region 27 is such that the angle of the apex 22b is approximately 20 degrees, and the reflecting surface, which is the boundary surface of the substantially V-shaped region 27, gradually bends in an arc along both elliptic arcs, and the light emitting element 16 is formed. G between the exit of the light and the entrance of the light receiving element 15
Is set to about 3.5 mm in the direction perpendicular to the optical axis O. The displacement between each focus position and the elliptical end in the elliptical region is about 10 μm, and therefore, the emission port of the light emitting element 16 and the incident port of the light receiving element 15 are arranged at the elliptical end and at the focal position. , There is virtually no difference. Further, at the rear end positions of the two elliptical regions (19a, 19b), similarly to the first embodiment, the emission port of the light emitting element 16 and the incidence port of the light receiving element 15 are arranged. Light emitting element 16
The light receiving element 15 is formed to have a size of about 1 mm square, and the emission port and the incidence port are configured to have a size of about 10 μm.

With the above arrangement, the elliptical regions (19a, 1a
The light emitted from the optical fiber 12 in which the end of the core 13 is located at each one of the focal points of 9 b) is apex 2 of the substantially V-shaped region 27.
It is divided into two directions by 2a, is totally reflected by an elliptic arc-shaped reflecting surface and is converged, and is condensed on the focal point on the rear end side of the elliptical regions (19a, 19b). The reflection surface of the substantially V-shaped region 27 is formed only on one side surface of the optical waveguide, but each arrangement angle of the light emitting element 16 and the light receiving element 15 is taken into consideration so that the light does not go to the other side surface. There is. Thus, it is not necessary to form the side clad layer on the other side surface, and the shape of the optical waveguide is simpler than that of the first embodiment.

Next, a third embodiment of the present invention will be described. FIGS. 4A to 4F and FIGS. 5A and 5B are cross-sectional views showing stepwise the manufacturing process of the optical module of this embodiment. Each drawing is drawn in a state viewed from the opposite direction to FIG.

In this embodiment, similar to the first embodiment, the V-shaped groove 21 is formed on the silicon substrate 14 by chemical etching (FIGS. 4 (a) and 4 (b)), and the component terminals and wirings are formed. The pattern 17 is formed by a copper plating pattern having a thickness of about 4 μm (FIG. 4 (c)). Furthermore, on the entire silicon substrate 14,
An ultraviolet curable epoxy resin 35 having a refractive index of about 1.50 is applied to a thickness of about 30 μm, and the dried and cured portion is used as the lower clad layer 26 (FIG. 4 (d)). The lower clad layer 26 is cured by exposing the mounting portions of the light emitting element 16 and the light receiving element 15 and the portion other than the installation position of the optical fiber 12 using an ultraviolet mask. The uncured portion during this exposure is developed after the core layer is formed.

Next, a wall 25 made of synthetic resin and having a height of about 30 μm from the lower clad layer 26 is formed as a platform on the peripheral portion of the ultraviolet curable epoxy resin 35 including the hardened lower clad layer 26. A solution 40 containing a liquid epoxy oligomer whose components are adjusted so that the refractive index after curing is 1.535 and a photopolymerization initiator is filled in this platform. After injecting the solution 40,
An ultraviolet mask is placed on the platform, and ultraviolet rays are radiated from the ultraviolet mask to cure the liquid epoxy oligomer according to the pattern of the ultraviolet mask (Fig. 4).
(e)).

The ultraviolet mask has the mounting areas of the light emitting element 16 and the light receiving element 15, the installation area of the optical fiber 12, and the substantially V-shaped side cladding layer 20 similar to the first or second embodiment. It has a pattern that shields a part. Except for the part shielded by the UV mask, it is cured by irradiation with UV light. The shielded mounting areas of the light emitting element 16 and the light receiving element 15 and the like are removed by developing the oligomer with an isopropanol solution, and the substantially V in the first or second embodiment is removed.
The core layer 40a excluding the character-shaped side cladding layer is obtained.
Further, the uncured portion of the ultraviolet curable epoxy resin of the lower clad layer 26 below the core layer 40a is developed and removed with an isopropanol solution to form the pattern of the lower clad layer 26 (FIG. 4 (f)). Here, the pattern of the optical waveguides (19a, 19b) is the same as that of the first embodiment.

Next, on the core layer 40a, the refractive index is 1.
Fifty UV curable epoxy resins are formed to a thickness of about 30 μm. Further, the optical fiber 1 is shielded with an ultraviolet mask.
2 and the portions other than the mounting portions of the light emitting element 16 and the light receiving element 15 are irradiated with ultraviolet rays to cure the ultraviolet curable epoxy resin, and the uncured portions are developed and removed to form the upper clad layer 28. (FIG. 5 (a)). Then, as in the first embodiment, the light receiving element 15 (light emitting element 16) is mounted on the wiring pattern 17 (18) and the optical fiber 12 is installed (FIG. 5B).

As described above, in the present embodiment, since the optical waveguide is formed by exposing and etching the UV-curable epoxy resin having high chemical stability, the environment resistance of the optical module is improved. The effect is obtained.

Next, a fourth embodiment of the present invention will be described. FIG. 6 is a cross-sectional view showing the manufacturing process of the optical module of this embodiment, and (a) to (e) show each step step by step. Each drawing is drawn in a state viewed from the opposite direction to FIG.

In this embodiment, similar to the first embodiment, the groove 21 having a substantially V-shaped plan is formed on the silicon substrate 14 by chemical etching, and the component terminal and the wiring pattern 17 (16) are formed. It is formed with a copper plating pattern having a thickness of about 4 μm. Further, an ultraviolet curable epoxy resin 35 having a refractive index of 1.50 is formed on the silicon substrate 14 to a thickness of 30 μm.
The lower clad layer 26 is formed by applying the coating to a thickness of about m (FIG. 6 (a)). The lower clad layer 26 has a first
Optical waveguides (19a, 19b) having a shape similar to that of the embodiment
The area is exposed using an ultraviolet mask to cure the ultraviolet curable epoxy resin 35, and the uncured oligomer is removed by developing with an isopropanol solution (FIG. 6 (b)).

Thereafter, a polyimide film 41 having a refractive index of 1.535 is formed on the lower clad layer 26 to have a thickness of about 10 μm to form a core layer (FIG. 6 (c)), and further on the polyimide film 41. Then, an ultraviolet curable epoxy resin is formed to a thickness of about 30 μm to form the upper clad layer 28 (FIG. 6 (d)).
Then, ultraviolet rays are applied to the regions of the optical waveguides (19a, 19b) on the upper clad layer 28 using an ultraviolet ray mask to cure the ultraviolet ray curable epoxy resin. This ultraviolet mask shields the mounting area of the light emitting element 16 and the light receiving element 15, the installation area of the optical fiber 12, and the portion forming the substantially V-shaped side clad layer in the first and second embodiments. Have a pattern.

Further, the uncured oligomer is developed with an isopropanol solution to remove the uncured portion of the UV-curable epoxy resin of the upper clad layer 28, and the upper clad layer 28 is patterned with the UV mask to form the pattern of the core layer (41). Form the same as. After the pattern is formed, the exposed portion of the polyimide film 41 of the core layer between the upper clad layer 28 and the lower clad layer 26 is dissolved and removed by alkali etching using the patterned upper clad layer 28 as an etching resist. To do.

Then, as in the third embodiment, a UV-curable epoxy resin having a refractive index of 1.50 is filled in the platform formed on the silicon substrate 14 at the height of the upper clad layer 28 to form a light emitting device. The mounting area of 16 and the light receiving element 15 and the installation area of the optical fiber 12 are shielded by an ultraviolet mask and exposed to ultraviolet rays to cure the ultraviolet curable epoxy resin. Further, the uncured portion is developed and dissolved and removed to form the side clad layer 20 (FIG. 1) of the core layers 19a and 19b, and the light emitting element 16 and the light receiving element 15 are formed in the same manner as in the first embodiment. After mounting on the component terminals 16 and 17, the optical fiber 12 is arranged.

As described above, in the present embodiment, the core layers 19a and 19b are made of polyimide, and the upper and lower clad layers 26 and 28 are respectively formed and then alkali-etched to obtain the optical waveguide. , 19b, the inclination of the side surfaces can be made closer to an ideal vertical surface. As a result, it is possible to obtain the effect of reducing the loss when the light is totally reflected by the reflecting surface.

As described above, the optical modules in the first to fourth embodiments have the reflecting surface which is an elongated elliptical boundary surface having a ratio r / R of the short axis r and the long axis R of 25, for example. . Therefore, the light emitted from the light emitting element 16 and the light receiving element 15 spreads at an angle of, for example, about 9.7 degrees, but this light flux is totally reflected by the reflecting surface which is the boundary surface of the elliptical region, and passes through the slab optical waveguide. Optical transmission can be smoothly performed among the light receiving element 15, the light emitting element 16, and the optical fiber 12.
Therefore, although it is not necessary to insert a plane lens for converging light into the optical system, the light reflection at the boundary surface of the core layer can be made good, and the side surface of the core layer is distorted and dust mixed in the core layer is generated. The effect of can be reduced.

Although the present invention has been described based on the preferred embodiments thereof, the optical module and the method of manufacturing the same of the present invention are not limited to the configurations of the above embodiments, and the embodiments described above are not limited thereto. An optical module in which various modifications and changes are made from the configuration of the example and a manufacturing method thereof are also included in the scope of the present invention.

[0060]

As described above, according to the optical module and the method of manufacturing the same of the present invention, it is possible to improve the light reflection in the optical waveguide while eliminating the need for the insertion processing of the flat lens for converging the light, and to achieve the core layer. It is possible to reduce the influence of the side surface distortion and dust mixed in the core layer.

[Brief description of drawings]

FIG. 1 is a plan view showing the configuration of an optical module according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a plan view showing the configuration of an optical module according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional view showing the manufacturing process of the optical module of the third embodiment, wherein (a) to (f) show each step step by step.

FIG. 5 is a cross-sectional view showing the manufacturing process of the optical module of the third embodiment, wherein (a) and (b) show each step step by step.

FIG. 6 is a cross-sectional view showing the manufacturing process of the optical module of the fourth embodiment, wherein (a) to (e) show each step step by step.

FIG. 7 is a side sectional view showing a conventional optical module.

FIG. 8 is a plan view showing a conventional optical module.

[Explanation of symbols]

11A, 11B: Optical module 12: Single-mode optical fiber 13: Core 14: Silicon substrate 15: Light receiving element (optical element) 16: Light emitting element (optical element) 17, 18: Wiring pattern 19a, 19b: optical waveguide 20: Side clad layer 23: Ball grid array 24: Photo-modifying material 26: Lower clad layer 27: Almost V-shaped area 28: Upper clad layer

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) G02B 6/122 G02B 6/13 G02B 6/30 H01S 5/022

Claims (4)

(57) [Claims] 1. An optical waveguide having a lower clad layer, a core layer and an upper clad layer, which are sequentially formed on a substrate, and a side clad layer , wherein the side clad layer is more refracted than the core layer. Low rate
Of a material, the boundary surface between the side cladding layer of the core layer, the boundary
An ellipse having a short axis r and a long axis R when viewed in the direction parallel to the plane
Forming at least part of the ratio of the minor axis to the major axis r / R
Means that the light flux in the core layer can be totally reflected at the boundary surface.
The field angle is smaller than the value expressed in radians, and the optical fiber or the light entrance of the light receiving element and the optical fiber or
The light emission ports of the light emitting element are respectively arranged at or near the two focal positions of the ellipse , and the light transmission from the light incidence port to the light emission port is performed through the core layer.
An optical module characterized by transmitting . 2. The optical module according to claim 1,
hand, The core layer has two ellipses between it and the side cladding layer.
The boundary surface consisting of a shape intersects the major axis of both ellipses in a V shape.
And the focus position of one of the two ellipses or its
Prepare so that the vicinity of An optical fiber is placed near each of the focal points of both ellipses.
A light receiving element or a light emitting element is arranged.
Optical module to do. 3. An optical fiber arranged at the focal position,
The optical axis of the light-receiving element or the light-emitting element is aligned with the long axes of the both.
Face the sandwiched direction, The boundary surface of the core layer with the side cladding layer is at least
Shape the ellipse in the inner region sandwiched by both major axes
The optical module according to claim 2, which is formed. 4. A manufacturing method for manufacturing an optical module having an optical waveguide, wherein a lower clad layer is formed on a substrate , and a core layer and a refractive index from the core layer are formed on the lower clad layer.
Low side cladding layer and the side cladding of the core layer.
The boundary surface with the dead layer is viewed in the direction parallel to the boundary surface, and the minor axis
an elliptical shape having r and a major axis R, said minor axis and major axis
The ratio r / R is such that the luminous flux can be totally reflected at the edge.
An ellipse that is smaller than the field angle expressed in radians
And the optical fiber or the light receiving element at the two focal points of the ellipse.
The light entrance of the child and the light exit of the optical fiber or the light emitting element.
A method for manufacturing an optical module, comprising: