JPH02156212A - Semiconductor laser module and its manufacture - Google Patents

Abstract

PURPOSE:To obtain such a semiconductor laser module being low in cost and small in size, and also, having a high performance by constituting it of a first fiber fixing part, and a second fiber fixing part for holding an optical fiber with a front spherical lens on a substrate. CONSTITUTION:The semiconductor laser module is provided with a semiconductor laser 1 installed through a buffer material 7 for absorbing a thermal expansion coefficient difference between a substrate 6 and itself in a position of a plane-like substrate 6 used as a heat sink, as well, a first fiber fixing part consisting of a first and a second fixing blocks 8, 9 for holding an optical fiber 5 with a front spherical lens coupled with the semiconductor laser 1 in the vicinity of the semiconductor laser 1 and adhesive agents 11, 11'. Also, said module is provided with a second fiber fixing part consisting of a fiber fixing frame 10 installed in a prescribed position in front of said first fiber fixing part, and an adhesive agent 11'' packed in the fixing frame 10. In such a way, an optical communication system of high reliability can be obtained at a low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fiber-attached semiconductor laser module used as a light source in the fields of optical communication and optical information processing.

[Conventional technology]

FIG. 8 shows a conventional optical system of a fiber-equipped semiconductor laser module. In order to efficiently guide the wide-angle output light emitted from the semiconductor laser 1 to the optical fiber 4 with a low 1a+angle, a two-lens system called a confocal system is used. That is, light with a wide aperture angle emitted from the semiconductor laser 1 is converted into a parallel beam by a short focus lens 2 matched to this aperture angle, and then converted into a parallel beam by a long focus lens 3 matched to the aperture angle of the optical fiber 4. It is configured to guide the optical fiber 4 to the optical fiber 4. In the above configuration, two lenses 2 and 3 are used.
However, there was a problem in that the number of parts increased. Further, although only the optical system is shown in FIG. 8, it actually has a complicated configuration in order to ensure a high degree of positioning accuracy for the two lenses 2 and 3. Therefore, the manufacturing cost is high, and the lens system occupies most of the volume of the module, resulting in a large size.

On the other hand, FIG. 9 shows an optical system of a fiber-equipped semiconductor laser module, which is envisioned when an optical fiber 5 with a spherical lens is used, which has a spherical lens at the tip of the optical fiber. In this case, as is clear compared to the conventional example shown in Figure 8, not only is there only one lens, but the lens is built into the end of the fiber, making the optical system extremely simple. . In addition, the coupling efficiency with a single mode optical fiber is also 1 oscillation wavelength of 1.3 when the radius R of the tip sphere is 10 μm.
With a μ7n semiconductor laser, a value of 2 to 3 dB, which is equivalent to or higher than the conventional example shown in Figure 8, can be obtained, so if a semiconductor laser module with this optical system is realized, the price will be lower than that of the conventional example. It is clear that the reduction in size and size can be realized.

[Problem to be solved by the invention]

” - The method using an optical fiber with a spherical lens at the tip (there was a problem in the accuracy of VCO determination. Figures 10 and 11 are the emission), 9 wavelengths 1.3 μm, full width at half maximum (F WHM )
01, (1// are respectively 30', 2: lo
InGaAsP semiconductor laser 1 and tip sphere radius R=l
FIG. 3 is a diagram showing the distance dependence of the coupling efficiency of Oμin with an optical fiber (single mode) with a spherical lens. FIG. 10 shows the distance dependence in the direction of the optical axis (dotted chain m in FIG. 9), and the distance ΔZ= between the semiconductor laser 1 and the optical fiber 5 with a spherical lens
Maximum coupling efficiency (56%, 2.5 dB) is obtained at 11 μm, and 1 dB tolerance (1 dB deterioration allowable displacement amount)
It turns out that is ±4.5 μm. on the other hand.

The eleventh is the distance dependence of the coupling efficiency in the direction perpendicular to the optical axis (X+'j axis direction in FIG. 9) when ΔZ=11 μm. As is clear from the figure, the 1dB tolerance is ±0
．． It turns out that it is 8 μm. As is clear from the above characteristics, a tolerance of ±4°5 μm in the optical axis direction can be fully achieved by positioning and fixing work using solder or adhesive, but in the direction FkM along the optical axis, it is submicron (±4°5 μm). A system consisting of a semiconductor laser and an optical fiber with a spherical lens, which requires an accuracy of 0.8 μm) and has no fixing method with excellent reproducibility and productivity, has the above-mentioned advantages, and has been developed into a practical module. It was extremely difficult to finish.

SUMMARY OF THE INVENTION An object of the present invention is to obtain an inexpensive, compact, and high-performance fiber-equipped semiconductor laser module that solves the problem of highly accurate positioning and fixing between an optical fiber with a spherical lens and a semiconductor laser.

[Means to solve the problem]

In order to achieve the above object, a semiconductor laser module according to the present invention has a semiconductor laser installed at a position on a flat substrate that also serves as a heat sink, with a warming material that absorbs the difference in thermal expansion coefficient between the semiconductor laser and the substrate. , a first fiber fixing portion comprising first and second fixing blocks and an adhesive for holding an optical fiber with a spherical lens coupled to the semiconductor laser near the semiconductor laser; The fiber fixing frame is constructed of a fiber fixing frame installed at a predetermined position in the hydraulic direction (Z-axis direction) of the fiber fixing part, and a second fiber fixing part made of an agglutinant filled in the fixing frame.

[Effect]

In order to adhesively fix the l~ object and the B object with high positioning accuracy, the following procedure is generally performed. First, before fixing A and B
The best position is determined by relatively displacing A and B while bringing their adhesive surfaces into contact with each other.

Next, A and B are crimped in the above positional relationship, and the fixing work such as soldering and adhesive injection is performed while suppressing the relative displacement of A and B during the fixing work due to the friction between AB. When the method of the present invention is applied to the coupling between the optical fiber with a spherical tip lens and the semiconductor laser, the above-mentioned configuration is obtained. In this case, it is impossible to bring the optical fiber with a spherical lens and the semiconductor laser into contact with each other, which should have a fixed positional relationship, both in principle and in terms of the strength of the object. Therefore, a fixing block to be brought into contact is provided near the lens portion of the optical fiber with a spherical lens and the semiconductor laser. At this time, as is clear from FIGS. 1O and 11, high positioning and fixing accuracy is required in two directions: the X-axis and the X-axis perpendicular to the optical axis.

For this reason, fixing blocks 8 and 9 as shown in FIGS. 1 and 2 are provided whose surfaces to be contacted, aligned and fixed are perpendicular to the optical axis. The fixing block 8 is fixed near the semiconductor laser l, the other fixing block 9 is kept in contact with the block 8, and in this state the lens and the semiconductor laser are adjusted to the best coupling position. Thereafter, the optical fiber 5 with a spherical lens is fixed to the block 9 using an adhesive 11, and the positions of the semiconductor laser 1 and the optical fiber 5 with a spherical lens in the optical axis direction are fixed. As shown in Figure 10, the optical axis direction (Z-axis direction) has a wide tolerance of ±4.5 μm, so it is possible to achieve sufficient clarity even when considering the effects of curing shrinkage of the adhesive, etc. Can be done.

Next, in the above situation, find the optimal position in the direction perpendicular to Mt.
After that, fixing block 9 is fixed to block 8.
Pressure, n. If the blocks 8 and 9 are fixed using the adhesive 11' in this state, the blocks 8 and 9 will not be displaced even during the curing process of the adhesive II', and the optical supplement 1
High precision positioning and fixing in one straight direction is achieved. The first fixing block 8 and the second fixing block 9 are 1. Although it is preferable to use quartz because it has the smallest difference in tensile coefficient, for example, an invar alloy may be used instead of quartz. Furthermore, although copper can be used as the material for the substrate 6, it is more preferable to use quartz or an invar alloy for the same reason as above.

The second fiber fixing part, which is made up of the fiber fixing frame lO and the adhesive 11', is for preventing external force from being applied to the fixing part of the semiconductor laser and the spherical lens.

As described above, in order to achieve highly accurate contact fixation between the optical fiber with a spherical lens and the semiconductor laser, the semiconductor laser module of the present invention includes a first fixing block provided on the side of the semiconductor laser, A second fixing block is provided on each optical fiber with a spherical lens.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a plan view showing one embodiment of a semiconductor laser module according to the present invention, FIG. 2 is a side view of the above embodiment, FIG. 3 is a perspective view showing (1 growth) of the above embodiment, and FIG. 5 is a diagram showing the structure of another embodiment of the semiconductor laser module, FIG. 6 is a side view of the other embodiment, and FIG. 7 is a diagram showing the other embodiment of the semiconductor laser module. FIG. 3 is a plan view of an example. In FIGS.
An InGaAsP semiconductor laser 1 with an oscillation wavelength of 1.3 μm is placed at a desired position on a copper block substrate 6 that also serves as a sink.
In order to absorb the difference in thermal expansion coefficient, the optical axis was set in the Z-axis direction and the upper side was bonded with Au-Sn (80-20) alloy through a buffer material 7 using SL to absorb the difference in thermal expansion coefficient. . Next, a U-shaped first fixing block 8 having a contact fixing surface 8' perpendicular to the optical axis is placed near the semiconductor laser 1 so that the contact fixing surface 8' is 2°2100 μm ahead of the light emitting surface ( Z-axis direction) and fixed with epoxy adhesive. Here, the semiconductor laser 1 has an element length of 300 μm.
m and the thickness is 100μm, and the thickness of the Si, I reinforcement material 7 is 400μm.
It was set as m. Next, the inner diameter is 400 μm, the outer diameter is 1000 μm,
A cylindrical fiber fixing frame IO with a length of 500 pm was placed at a position 1.5 mm away from the semiconductor laser 1.
It was installed so that the center line almost coincided with the optical axis and fixed with epoxy adhesive. The material of the fixing frame 10 is alumina.

Next, as shown in FIG. 4, the substrate 6 is placed on a holding stand so that the optical axis direction (Z-axis) is parallel to the direction of gravity and the traveling direction of light (Z-axis direction) is opposite to gravity. Fixed.

After that, it has a contact fixing surface perpendicular to the optical axis, and the position assumed to be the optical axis of the fiber guide section almost coincides with the position of the center of gravity.

A second fixing block 9 was prepared and placed on top of the first fixing block 8 so that the optical axes were substantially aligned (FIG. 4, ■). Next, an optical fiber 5 with a tip lens (tip sphere diameter R = 10 μm) is fixed to a fine movement table (not shown).
(single mode optical fiber) is passed through the fiber fixing frame 10 from above in parallel to the optical axis, and the semiconductor laser 1
while monitoring the output light from the fiber 5.

The coupling with the semiconductor laser 1 was adjusted to the best condition.

At this time, the coupling loss was 2.5 dB. Here, the purpose of setting the optical axis in the direction of gravity as described above is to prevent gravity and buoyancy due to the adhesive from acting in the direction xt', which requires high precision, and to align the optical axis with respect to the optical fiber 5. This is to mechanically stabilize the optical system by applying tension in the parallel direction. Particularly in a submicron placement process such as the semiconductor laser module of the present invention, the above arrangement is an essential operation. Next, apply epoxy adhesive between the second fixing block 9 and the tip spherical lens optical fiber 5.
Pour enough amount to bond and fix only the upper two parts and let it solidify (
4), thereby fixing the position between the semiconductor laser and the front lens in two directions. The second fixing block 9 shown in No. 4 (A) has a fixing groove for the optical fiber 5, but the manufacturing process is the same even if the fixing block is provided with a fixing spatula. .During the above process x,
Since the force position in the yJ [t1 direction is slightly deviated from the best position, the optical fiber with a tip lens is connected while the second 1.1 fixing block 9 and the first fixing block 8 are left alone. 5
X.

After adjusting it to the best position by pushing it in the y・i+h direction, mJ! is holding the optical fiber 5! Using an IJ device, several tens of grams of force was applied in the optical and lateral directions of the optical fiber 5 to press the fixing blocks 8 and 9 together (FIG. 4, ■).

At this time, the coupling loss between the semiconductor laser 1 and the optical fiber 5 was 2.7 dB. In the above state, epoxy adhesive was applied across fixing blocks 8 and 9, but
The adhesive entered the gap between blocks 8 and 9 due to surface tension and solidified (Fig. 4 ■).

During this time, since the block 8 was crimped to the block 9, the mutual positional relationship did not change, and there was no change in the coupling loss.

Finally, in order to prevent external force from being applied to the semiconductor laser 1 and the lens fixing part due to fiber cutting work, etc., a central The optical fiber 5 was fixed by injecting adhesive through the hole in the hole, and the semiconductor laser module was completed as shown in FIG. 4 (■).

The fixing blocks 8 and 9 are preferably made of a material with a small coefficient of thermal expansion in order to minimize the displacement between the semiconductor laser and the lens due to temperature changes. A similar effect can be obtained by using a nickel-based invar alloy. In this embodiment, since the substrate 6 is a simple type that also serves as a heat sink for the semiconductor laser 1, copper is used as the material for the substrate 6.

Next, another embodiment will be described which is a highly reliable semiconductor laser module that takes into consideration the resistance to bees 1 to circles over a wide temperature range. FIG. 5 shows the difference between the optical fiber 5 with a spherical lens and the substrate 6 due to the difference in coefficient of thermal expansion.
FIG. 2 is a perspective view of an optical fiber module with a spherical tip lens manufactured in order to solve the misalignment between the semiconductor laser and the lens caused by fatigue of the fixed part and the second fixed part. In this example, first, a block body in which the substrate 6 and the first fixing block 8 were integrated was fabricated from quartz.

Next, a silicon substrate 7 was provided on a copper block 6', which is a heat sink material, so as to protrude from the copper block 6' by a desired distance as shown in the figure, and a semiconductor laser 1 was placed on this protrusion. As shown in FIGS. 6 and 7, the protruding semiconductor laser 1 is placed between the fixing blocks 8 and the substrate 6 and the copper heat sink 6
′ were attached using epoxy adhesive. Thereafter, a fiber fixing frame 10 also made of quartz was placed on the substrate 6 so that the center line of the fixing frame 10 substantially coincided with the optical axis. When such a configuration was manufactured by the same process as described in the above example, an optical fiber 5 with a tip lens was obtained.
The problem of the difference in thermal expansion coefficient between the substrate 6 and the substrate 6 has been solved, and a highly reliable fiber-attached semiconductor laser module with no characteristic deterioration can be obtained even after heat cycles of -20°C to +70°C are repeated over 1000 times. Ta.

Furthermore, considering that a semiconductor laser is a waveguide type optical device that reflects the refractive index of an active layer and a cladding layer surrounding it, the present invention is made of a silica-based optical fiber and an m-v group bioconductor material. It is clear that the present invention can be applied to connections of high NA waveguide type optical devices in general.

〔Effect of the invention〕

As described above, the semiconductor laser module according to the present invention has
a step of installing a semiconductor laser on a substrate; a step of installing a first fixing block near the semiconductor laser;
A step of installing an optical fiber fixing frame on the front substrate of the semiconductor laser, and installing the substrate on a jig so that the assumed optical axis is parallel to the direction of gravity and the direction of light travel is opposite to the direction of gravity. (2) a step of attaching the second fixing block with the adhesive surface facing downward so that the optical fiber fixing groove or fixing hole on the first fixing block substantially coincides with the optical axis; A process of passing the optical fiber with a spherical lens through the fixed frame from above and adjusting its position in order to match it with the semiconductor laser with the highest efficiency;
The process of inserting the concubine 1 agent between the fixing blocks and solidifying it, and the tip lens and 4-light fufu-rebar and '! - Place lJ to combine with the body laser with maximum efficiency = 3! After I, the optical fiber with a spherical lens is pressed downward parallel to the direction of the sun, and the second fixing block is TTF-, u-fixed to the fixing block '51, and the above-mentioned first and second The process of inserting the adhesive into the adhesive surface sandwiched between the fixing blocks by surface tension and then solidifying it, and the process of forward fixation.
By injecting adhesive into the frame 11 from the adhesive injection hole and fixing the adhesive, highly accurate positioning and fixing between the semiconductor laser and the optical fiber can be realized. Therefore, due to the simple configuration and high performance of this optical system, it is possible to fabricate an extremely inexpensive and high-performance fiber-attached semiconductor laser module, and it is possible to realize a low-cost highly reliable optical communication system. can.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing one embodiment of a semiconductor laser module according to the present invention, FIG. 2 is a side view of the above embodiment, FIG. 3 is a perspective view showing the configuration of the above embodiment, and FIG. 4 is a plan view showing the above embodiment. 521 is a diagram showing the structure of an actual example of the semiconductor laser module, FIG. 6 is a side view of the other embodiment described above, and FIG. 7 is a diagram showing the structure of the other embodiment described above. Plane A, Figure 8 shows the optical system of a conventional fiber-equipped semiconductor laser module, Figure 9 shows the optical system of a semiconductor laser module using an optical fiber with a spherical lens, and Figure 10 shows the semiconductor laser module. FIG. 11 is a diagram showing the dependence of the coupling characteristics of the optical fiber with a spherical lens on each other in the optical axis direction, and FIG. 11 is a diagram showing the distance dependence of the coupling characteristics in the direction perpendicular to the optical axis. 1... Semiconductor laser 5... Optical fiber with tip spherical lens 6... Substrate 8... First fixing block 9... Second fixing block 10... Second fiber fixing part patented Akihito Nippon Telegraph Report Patent Attorney Co., Ltd.
Junnosuke Nakamura 2nd Beef JaL-γ. 5; Procedural amendment for the 6:1 version with a forward lens and a 4-bar forward lens (spontaneous) December 7, 1999

Claims (1)

[Claims] 1. A semiconductor laser installed at a desired position on a flat substrate, and an optical fiber with a spherical tip lens optically coupled to the semiconductor laser through a lens section provided at its tip. and a first member having an adhesive surface perpendicular to the optical axis at a predetermined position on the substrate near the laser, and fixed such that the adhesive surface is located a predetermined distance in front of the light emitting surface of the semiconductor laser. A fixing block, an optical fiber fixing groove or a fixing hole parallel to the optical axis, and an adhesive hold the lens portion of the optical fiber with a tipped lens, and have an adhesive surface perpendicular to the optical axis. , a first fixing block comprising a second fixing block whose adhesive surface is held on the adhesive surface of the first fixing block with an adhesive;
and a second fiber that holds the optical fiber with a bulbous lens on the substrate at a position a predetermined distance ahead of the optical fiber holding position of the bulbous lens of the second fixing block. A semiconductor laser module consisting of a fixed part. 2. The second fiber fixing part has a hole that is parallel to the optical axis, the center axis of which is substantially coincident with the optical axis, and that is sufficiently larger than the outer diameter of the optical fiber with a spherical lens at the center. It is characterized by comprising a front fixing frame having an adhesive injection hole and installed on the substrate, an optical fiber passing through the fixing frame, and an adhesive filling a gap in the frame. A semiconductor laser module according to claim 1. 3. A step of installing a semiconductor laser on a substrate, a step of installing a first fixing block near the semiconductor laser, a step of installing an optical fiber fixing frame on the front substrate of the semiconductor laser, and an assumption that installing the substrate on a jig so that the optical axis is parallel to the direction of gravity and the traveling direction of light is opposite to the direction of gravity; and installing an optical fiber fixing groove or fixing on the first fixing block. A process of placing the second fixing block with the adhesive side facing down so that the hole almost coincides with the optical axis, and passing the optical fiber with a spherical lens through the fixing frame from above to couple it with the semiconductor laser with maximum efficiency. A process of adjusting the position of the optical fiber with a lens tip and a step of inserting and solidifying the adhesive between the optical fiber with a lens tip and a second fixing block, and a step of adjusting the position of the optical fiber with a tip lens and a semiconductor laser with maximum efficiency. After adjusting the position so as to be coupled, pressing the optical fiber with a bulbous tip downward parallel to the optical axis direction and crimping and fixing the second fixing block to the first fixing block; and a step of inserting the adhesive into the adhesive surface sandwiched between the second fixing blocks by surface tension and then solidifying it, and a step of injecting the adhesive from the adhesive injection hole into the front fixing frame and fixing it. , a method for manufacturing a semiconductor laser module that is sequentially formed.