JPH09159878A - Light emitting element module and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce bending stress applied to a diffraction grating part and reduce variation in diffraction wavelength which is caused by the application of the bending stress to the diffraction grating part by fixing an optical fiber onto a substrate where a diffraction grating is formed. SOLUTION: The substrate 10 has a V groove 11 formed from one end to the center. On this substrate 10, a semiconductor laser 20 as a light emitting element is fixed at a specific position on the prolongation of the V groove 11. Then, a semiconductor light receiving element 21 is fixed on the substrate 10 on the side of the reflecting surface 20a of the semiconductor laser 20. In the V groove 11, one end part of the optical fiber 30 to be fixed is arranged. This optical fiber 30 has the diffraction grating 31 formed at the fixation end fixed onto the substrate 10 and the formation position of the diffraction grating 31 is positioned right in the V groove 11. Then the optical fiber 30 positioned in this V groove 11 is coated with a resin adhesive and the optical axis is aligned before the resin adhesive is hardened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting element module used as a signal light source for optical communication, a pumping light source for a fiber amplifier, and a method for manufacturing the same.

[0002]

2. Description of the Related Art The structure of a conventional light emitting device module is shown in FIG. This module consists of a package 101, a semiconductor laser 102,
The lens 103 and the optical fiber 104 are configured such that the incident ends thereof are fixed. Further, of the light emitted from the semiconductor laser 102, the diffraction grating 10 that reflects light of a specific wavelength.
5 is formed in the core portion of the optical fiber 104.

As described above, in the conventional module, since the portion of the optical fiber 104 on which the diffraction grating 105 is formed is out of the package 101, bending stress is applied to the portion on which the diffraction grating 105 is formed and the diffraction wavelength is increased. There is a problem that the light emitting element module shifts, and in such a case, the oscillation wavelength of the light emitting element module shifts.

Conventionally, when fixing the incident end of the optical fiber 104 onto the package 101, the package 1
The optical fiber 104 was aligned using the V groove formed on the surface 01. That is, when the fixed end of the optical fiber 104 is placed in the V groove, the outer peripheral portions of the optical fiber 104 come into contact with the inclined surfaces on both sides forming the V groove, so that the positioning is automatically performed.

However, due to the tolerance of the dimensional accuracy of the V-groove and the outer diameter of the optical fiber 104, the positions of the semiconductor laser 102 and the optical fiber 104 do not coincide with each other and the optical coupling efficiency is lowered. Moreover, when the semiconductor laser 102 is mounted on the package 101, a positional shift may occur, and in such a case as well, the optical coupling efficiency is similarly reduced.

Therefore, the present invention has been made to solve these problems, and an object of the present invention is to provide a light emitting element module capable of maintaining a constant oscillation wavelength and a manufacturing method thereof.

Another object of the present invention is to provide a light emitting element module which can obtain high optical coupling efficiency between the light emitting element and the optical fiber, and a method for manufacturing the same.

[0008]

A light emitting device module according to claim 1 has a substrate, a reflecting surface having a high reflectance and an emitting surface having a reflectance lower than the reflecting surface,
A semiconductor light-emitting element fixed on this substrate and a diffraction grating whose one end is fixed on the substrate and into which light emitted from the emission surface is incident and which reflects light of a specific wavelength among the incident light are provided. In a light emitting element module that includes at least an optical fiber formed in a core part and repeatedly reflects light of a specific wavelength between a reflecting surface and a diffraction grating, the optical fiber is formed by a diffraction grating. The featured part is fixed on the substrate.

By fixing the portion where the diffraction grating is formed on the substrate as described above, the bending stress applied to the diffraction grating portion is reduced.

In the light emitting element module according to claim 2,
A resin adhesive is interposed between the optical fiber and the substrate. Further, in the light emitting element module according to claim 3, the portion of the substrate where the optical fiber is fixed has a groove portion along the optical fiber, and the portion of the optical fiber where the diffraction grating is formed is formed in the groove portion. Fixed on top and configured.

With this configuration, the optical fiber before being fixed is in a state of being separated from the substrate or the groove portion thereof,
The substrate or the groove is prevented from interfering with the alignment of the optical fiber.

Therefore, as in the light emitting element module according to the fourth aspect, when the optical fiber is brought into contact with the groove,
It is necessary that the center of the optical axis of the optical fiber is located lower than the light emitting position of the semiconductor light emitting element. Further, as in the light emitting element module according to claim 5, the optical fiber may be fixed between the substrate and the protective substrate having the groove along the optical fiber.

Further, as in the light emitting device module according to claims 6 to 8, the semiconductor light receiving device, the conductor pattern, and the lens may be further provided on the substrate.

Further, as in the light emitting element module according to claim 9, the substrate can be formed of any one of semiconductor material, ceramic material, metal material, glass material and glass ceramic material. .

On the other hand, in the method for manufacturing a light emitting device module according to a tenth aspect, a step of positioning one end of the optical fiber to be fixed in the resin adhesive applied on the substrate and an optical step in the resin adhesive before curing. The method includes the steps of displacing the fiber and aligning the optical axis with the semiconductor light emitting element on the substrate, and curing the resin adhesive after the alignment.

By thus positioning the optical fiber in the resin adhesive, the optical fiber and the surface of the substrate are separated from each other, and the optical fiber can be displaced vertically and horizontally with respect to the substrate.

According to the eleventh aspect of the present invention, there is provided a method for manufacturing a light emitting element module, wherein the resin adhesive coated on the substrate is
Positioning one end of the optical fiber to be fixed, displacing the optical fiber in the resin adhesive before curing, and aligning the optical axis with the semiconductor light emitting element on the substrate, and further aligning And a step of curing the resin adhesive while continuing.

Since the resin adhesive is cured while the core is aligned as described above, it is possible to prevent the optical axis shift due to the solidification of the resin.

Further, in the method for manufacturing a light emitting device module according to the twelfth aspect of the invention, the aligning causes the light from the semiconductor light emitting device to enter the optical fiber and the optical output of the optical fiber becomes a desired value. First, the optical fiber is displaced in the resin adhesive.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION A method of manufacturing a light emitting device module according to this embodiment will be described below in the order of steps.

First, FIG. 1 shows a substrate 10 for fixing a semiconductor laser, an optical fiber and the like which will be described later. The substrate 10 is made of ceramics and has a V groove 11 formed from one end toward the center as shown in the drawing. This V groove 1
No. 1 is mainly formed so that the resin adhesive to be applied later is accumulated therein, and is not for positioning the optical fiber by utilizing the two inclined surfaces of the V groove 11. Therefore, although the end surface shape of this groove is illustrated as a V-shape here, the shape is not limited to this shape, and a groove such as a semicircle or a rectangular shape in which the applied resin adhesive can accumulate is formed inside. It should have been done.

Therefore, first, the semiconductor laser 20 as a light emitting element is fixed on the substrate 10 at a predetermined position on the extension line of the V groove 11 (FIG. 2). The semiconductor laser 20 is
Like a general Fabry-Perot type semiconductor laser,
It is composed of an nGaAsP / InP heterostructure, and a reflecting surface 20a is formed on one end surface of this heterostructure and an emitting surface 20b is formed on the opposite side. Reflective surface 2
0a is the output wavelength of the semiconductor laser 20, 1.31 μ.
Reflects light with a wavelength of m at a high reflectance of about 80% or more,
The emission surface 20b has a low reflectance of about 0.5% or less for light having a wavelength of 1.31 μm.

Next, the semiconductor light receiving element 21 is fixed on the substrate 10 on the reflecting surface 20a side of the semiconductor laser 20 (FIG. 2).
reference). The light-transmitted state of the semiconductor laser 20 is monitored by receiving the light transmitted from the reflecting surface 20a by the semiconductor light receiving element 21.

Next, one end of the optical fiber 30 to be fixed is placed in the V groove 11 (FIG. 3). This optical fiber 3
In the core portion of 0, the effective refractive index is periodically changed between the minimum refractive index and the maximum refractive index according to the position along the optical axis, and the diffraction grating is utilized by utilizing this refractive index change. 31 is formed. Further, in the optical fiber 31, the diffraction grating 31 is formed at the fixed end fixed on the substrate 10, and the portion where the diffraction grating 31 is formed is located exactly in the V groove 11.

In this state, the positional relationship between the light emitting position of the semiconductor laser 20 and the optical axis center of the optical fiber 30 is
It is as shown in FIG. That is, the height h2 of the optical fiber 30 at the center of the optical axis is set to be lower than the height h1 of the emission position of the semiconductor laser 20. That is, the optical axes of the two do not match in this state. The illustrated height h is based on the bottom surface of the substrate 10.

Next, the optical fiber 3 located in the V groove 11
0 is coated with the resin adhesive 40 (FIG. 5), and the optical axis is aligned before the resin adhesive 40 is solidified. Examples of the resin adhesive 40 include epoxy resin, acrylate adhesive, and ceramic adhesive.

By applying the resin adhesive 40 into the V groove 11, the resin adhesive 40 is interposed between the optical fiber 30 and the V groove 11, and the optical fiber 30 is separated from the V groove 11. It will be in the state (FIG. 6). As a result, the optical fiber 30 can be displaced vertically and horizontally with respect to the substrate 10. Therefore, thereafter, while the emitted light of the semiconductor laser 20 is made incident on the optical fiber 30, the optical fiber 30 located in the resin adhesive 40 is displaced so that the fiber end output becomes a desired value. Align with.

Next, the resin adhesive 40 is irradiated with ultraviolet rays to be UV-cured. Even during the curing, the desired high optical coupling efficiency can be obtained even after the curing by continuing the above-mentioned alignment work.

The light emitting element module is manufactured through the above steps, but at this time, the optical fiber 3 coated with the resin adhesive 40 is used.
It is also possible to employ a structure in which the upper part of 0 is covered with an upper substrate 12 formed of the same material as the substrate 10 and having a V groove 13 (FIGS. 7A and 7B). As described above, by covering the portion coated with the resin adhesive 40 with the upper substrate 12, the fixing strength of the optical fiber 30 can be increased, and thus the optical axis shift is reduced.

Further, as shown in FIG.
The condenser lens 50 may be fixed between the semiconductor laser 20 and the semiconductor laser 20. By optically coupling the optical fiber 30 and the semiconductor laser 20 via the condenser lens 50 in this manner, higher optical coupling efficiency can be obtained.

Further, as shown in FIG. 9, a conductor pattern 14 made of a metal containing Au or Al is formed on the surface of the substrate 10.
It is also possible to use the substrate 10 'on which is formed. The conductor pattern 14 is used for the semiconductor laser 20 and the semiconductor light receiving element 2.
Used for fixing 1 and wiring.

In the above embodiment, the V-groove 11 is formed on the surface of the substrate 10, but the V-groove 1 is used.
Even if a flat substrate without 1 is used, the light emitting device module can be manufactured in the same manner as the manufacturing process described above. in this case,
When the optical fiber 30 is positioned in the resin adhesive 40 applied on the flat substrate 10 ″, the substrate 10 ″ and the optical fiber 30 are separated from each other as shown in FIG. In this state, the optical fiber 30 is displaced vertically and horizontally to perform optical axis alignment, and after the alignment, the resin adhesive 40 is solidified.

The material of the substrate 10 is exemplified as ceramics, but other than this, metal or Al is used as the substrate material.
N can also be used. In this case, since the thermal conductivity is good, when the semiconductor laser is fixed on the substrate, the semiconductor laser that has generated heat can be efficiently dissipated. Further, by using a material having a linear expansion coefficient similar to that of the optical fiber for the substrate 10, such as quartz, silicon, AlN, glass ceramics, and mullite, it is possible to reduce thermal stress applied to the optical fiber due to temperature change. In addition, InP and GaA
If a semiconductor substrate such as s is used, a semiconductor laser and a semiconductor light emitting element can be monolithically formed on the substrate. Further, when a glass material is used as the substrate, when UV curable resin is used as the resin adhesive, when fixing the optical fiber onto the substrate, it is possible to irradiate UV light from the front surface as well as the back surface of the substrate. Therefore, the adhesive can be uniformly hardened.

Further, in the above-described embodiment, an example in which the optical fiber 30 and the semiconductor laser 20 are fixed on the same substrate 10 has been shown. However, after fixing the optical fiber 30 and the like to separate substrates, the substrates are separated from each other. It is also possible to align the optical axis by performing alignment or the like.

[0035]

As described above, according to the light emitting element module of the first to ninth aspects, since the portion of the optical fiber on which the diffraction grating is formed is fixed on the substrate, the diffraction grating portion is formed. Since the bending stress applied to can be reduced,
It is possible to reduce the fluctuation of the diffraction wavelength, which is caused by the bending stress applied to the diffraction grating portion.

Further, according to the method for manufacturing a light emitting device module according to the tenth to twelfth aspects, by positioning the optical fiber in the resin adhesive, the optical fiber and the substrate surface are separated from each other, and The optical fiber can be displaced vertically and horizontally. Therefore, fine alignment can be performed and higher optical coupling efficiency can be obtained, as compared with the conventional alignment that depends on the shape itself of the V groove or the outer diameter of the fiber.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a substrate used in this embodiment.

FIG. 2 is a plan view showing a state in which a semiconductor laser and a semiconductor light emitting element are mounted on the substrate shown in FIG.

FIG. 3 is a plan view showing a state in which fixed ends of optical fibers are arranged on the substrate shown in FIG.

FIG. 4 is an explanatory diagram showing a positional relationship between an optical axis center of an optical fiber located in a V groove and an emission position of a semiconductor laser.

FIG. 5 is a plan view showing a state where a resin adhesive is applied to the fixed end portion of the optical fiber, following FIG. 3;

FIG. 6 is an explanatory diagram showing a state in which the optical fiber and the substrate are separated from each other when a resin adhesive is applied to the fixed end portion of the optical fiber.

7A is a plan view showing a structure in which an upper substrate covers an upper portion of an optical fiber coated with a resin adhesive, and FIG. 7B is an explanatory diagram showing a fixed state of the optical fiber in the case of FIG. 7A. Is.

FIG. 8 is a plan view showing another embodiment of the light emitting device module.

FIG. 9 is a plan view showing another embodiment of the light emitting device module.

FIG. 10: The fixed end of the optical fiber is arranged on a flat substrate,
It is explanatory drawing which shows the state which applied the resin adhesive agent.

FIG. 11 is a plan view showing a conventional light emitting device module.

[Explanation of symbols]

10 ... Substrate, 11 ... V groove, 12 ... Upper substrate (protective substrate), 20 ... Semiconductor laser (semiconductor light emitting element), 20a
... Reflecting surface, 20b ... Emitting surface, 21 ... Semiconductor light receiving element, 3
0 ... Optical fiber, 31 ... Diffraction grating, 40 ... Resin adhesive.

Claims (12)

[Claims] 1. A semiconductor light emitting device having a substrate, a reflecting surface having a high reflectance and an emitting surface having a reflectance lower than that of the reflecting surface, and one end of the semiconductor light emitting element on the substrate. And a light emitted from the emitting surface is incident, and an optical fiber having at least a core formed with a diffraction grating that reflects light of a specific wavelength of the incident light, the specific wavelength In a light emitting element module that performs laser oscillation by repeatedly reflecting the light of 1 between the reflection surface and the diffraction grating, the optical fiber has a portion where the diffraction grating is formed fixed on the substrate. A light emitting device module characterized by the above. 2. The light emitting device module according to claim 1, wherein a resin adhesive is interposed between the optical fiber and the substrate. 3. The substrate has a groove portion along the optical fiber in a portion where the optical fiber is fixed, and a portion where the diffraction grating is formed in the optical fiber,
The light emitting device module according to claim 2, which is fixed on the groove. 4. The optical axis center of the optical fiber is lower than the light emitting position of the semiconductor light emitting element when the optical fiber is in contact with the groove.
The light emitting device module described. 5. The method according to claim 2, further comprising a protective substrate having a groove portion along the optical fiber, wherein the optical fiber is fixed between the protective substrate and the substrate. Light emitting device module. 6. The light emitting device according to claim 2, further comprising a semiconductor light receiving device for monitoring light transmitted through the reflecting surface on the substrate on the reflecting surface side of the semiconductor light emitting device. module. 7. The light emitting device module according to claim 2, wherein a conductor pattern is formed on the substrate. 8. The light emitting element module according to claim 2, further comprising a lens for condensing light propagating between the semiconductor light emitting element and the optical fiber on a substrate. . 9. The substrate according to claim 1, wherein the substrate is made of any one of semiconductor materials, ceramic materials, metal materials, glass materials and glass ceramic materials.
8. The light emitting device module according to any one of 8. 10. A step of locating one end of an optical fiber to be fixed in a resin adhesive applied on a substrate, and displacing the optical fiber in the resin adhesive before curing to form a semiconductor on the substrate. A method for manufacturing a light-emitting element module, comprising: a step of aligning an optical axis with a light-emitting element; and a step of curing the resin adhesive after the alignment. 11. A step of locating one end of an optical fiber to be fixed in a resin adhesive applied on a substrate, and displacing the optical fiber in the resin adhesive before being cured to form a semiconductor on the substrate. A method of manufacturing a light-emitting element module, comprising: a step of aligning an optical axis with a light-emitting element; and a step of curing the resin adhesive while continuing the alignment. 12. The optical fiber is arranged in the resin adhesive so that the alignment allows light from the semiconductor light emitting element to enter the optical fiber and the optical output of the optical fiber has a desired value. The method for manufacturing a light-emitting element module according to claim 10, wherein the method is performed by displacing.