JP2007115933A - Optical semiconductor module and its assembling method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical semiconductor module and its assembling method for suppressing a decrease in optical coupling efficiency caused by an optical axis misalignment of a lens, and for stabilizing optical coupling efficiency. <P>SOLUTION: A semiconductor laser 101, a first lens 102 for making a light emitted from the semiconductor laser 101 parallel rays, a second lens 103 for collecting the parallel rays, and a semiconductor optical modulator 104 arranged at a position where the light collected by the second lens 103 is coupled to a light guide, are mounted on a submount 105. The focal length of the first lens 102 and the focal length of the second lens 103 of the optical semiconductor module are different each other. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical semiconductor module and an assembling method thereof, and more particularly to an optical communication system and an optical semiconductor element used in an optical information processing system.

  In the conventional optical semiconductor module, when two optical semiconductor elements are optically coupled via a lens, two lenses having substantially the same focal length are used in order to obtain high optical coupling efficiency. This is because the light field diameter of the semiconductor element, that is, the full width at half maximum (FWHM) of the power distribution of light propagating in the optical semiconductor element is about 2 μm, which is the same for all types of elements. This is because, in the coupling, by using two lenses having substantially the same focal length and setting the image magnification to approximately 1, an optical coupling with a small loss can be obtained (for example, see Non-Patent Document 1).

That is, according to Non-Patent Document 1, the image magnification is m, the field diameter of the first semiconductor element is w ₁ , the field diameter of the second semiconductor element is w ₂ , and the light emitted from the first semiconductor element is It is described on page 58 of Non-Patent Document 1, where f _{1 is} the focal length of the first lens to be collimated, and f ₂ is the focal length of the second lens that collects the light transmitted through the first lens. (4.3-6), the optimum image magnification m _opt for obtaining the maximum optical coupling efficiency is ₁ when the field diameters of the two elements are equal (w ₁ = w ₂ ). From the equation (4.2-16) described on page 56 of Non-Patent Document 1, when the image magnification m _opt = 1, the focal points of the two lenses that can obtain the maximum optical coupling efficiency in the optical coupling between the semiconductor elements. The relationship between the distances f ₁ and f ₂ is f ₁ = f ₂ . Therefore, it can be seen that the optical semiconductor module can obtain the maximum optical coupling efficiency when the focal lengths of the two lenses are equal.

  On the other hand, when the lens is fixed, that is, with respect to the optical axis connecting the emission end of one optical semiconductor element and the incident end of the other optical semiconductor element, the positional deviation of the lens that occurs in the direction perpendicular to this axis In order to compensate for the decrease in optical coupling efficiency due to lack of freedom of position adjustment, for example, as shown in FIG. 1, page 197 of Non-Patent Document 2, a third lens is provided between the two lenses. Or an optical component such as a prism for correcting the light beam axis is required.

Kenji Kono, “Fundamentals and Applications of Optical Coupling Systems for Optical Devices,” Hyundai Kogakusha Publishing, 1991, p.54-61 K. Anderson et al, "Design and Manufacturability Issues of a Co-packaged DFB / MZ Module", Electronic Components and Technology Conference, 1999, Proceedings, pp.197-200

  However, if two lenses having substantially the same focal length are used for optical coupling between the two optical semiconductor elements, the coupling loss with respect to the axial deviation of the lens increases. For example, when an adhesive such as an epoxy resin is used to fix a lens or an optical component for correcting the optical axis, the long-term stability of the lens position is poor, and the optical coupling efficiency changes significantly with time. There was a risk that the output light intensity would decrease. Also, if fixing means by YAG laser welding is used to fix lenses and optical components for optical axis correction, long-term stability can be secured, but optical coupling efficiency deteriorates due to axial misalignment during welding, There was a problem that the output light intensity decreased.

  When the lens is fixed by YAG laser welding, a deviation of several μm occurs in the lens position with the expansion and contraction that occurs during melting and solidification of the metal during welding. On the other hand, the light field diameter of the optical semiconductor element is about 2 μm, which is smaller than the axial misalignment during welding. For this reason, degradation of optical coupling efficiency due to axial misalignment has been a major problem.

  In view of the above, an object of the present invention is to provide an optical semiconductor module having a stable optical coupling efficiency and a method for assembling the same, by suppressing a decrease in optical coupling efficiency due to an axial shift of the lens.

  An optical semiconductor module according to claim 1 of the present invention for solving the above-described problem includes a first optical semiconductor element and a first lens that converts light emitted from the first optical semiconductor element into parallel rays. And a second lens for condensing the parallel rays and a second optical semiconductor element disposed at a position where the light collected by the second lens is coupled to the optical waveguide on a common submount. In the mounted optical semiconductor module, the focal length of the first lens and the focal length of the second lens are different from each other.

  The optical semiconductor module according to claim 2 of the present invention is the optical semiconductor module according to claim 1, wherein the field diameter of the first optical semiconductor element and the field diameter of the second optical semiconductor element are substantially equal. And

  An optical semiconductor module according to a third aspect of the present invention is the optical semiconductor module according to the first or second aspect, wherein an axial displacement amount of the lens generated during assembly is a field of the first and second optical semiconductor elements. It is characterized by being equal to or larger than the smaller field diameter of the diameters.

  An optical semiconductor module according to a fourth aspect of the present invention is the optical semiconductor module according to any one of the first to third aspects, wherein a ratio of focal lengths of the two lenses is 1: 1.5 or more and 1: An optical system having an image magnification of 1.5 times or more and 2.5 times or less is formed.

  An optical semiconductor module assembling method according to a fifth aspect of the present invention is a method for assembling the optical semiconductor module according to any one of the first to fourth aspects, wherein a metal housing containing the lens is attached to a YAG laser. It is fixed on the submount through a lens holder by welding.

  An optical semiconductor module assembling method according to claim 6 of the present invention is a method of assembling the optical semiconductor module according to any one of claims 1 to 4, wherein the two optical semiconductor elements are mounted on the submount. After fixing the lens, the position of the lens is adjusted, and when fixing the first lens and the second lens having different focal lengths, a lens having a short focal length is fixed on the submount first, A lens having a long distance is fixed on the submount later.

  An optical semiconductor module according to a seventh aspect of the present invention is manufactured by the method for assembling an optical semiconductor module according to the fifth or sixth aspect.

  The above-described optical semiconductor module according to the present invention uses two lenses having different focal lengths to enlarge the image magnification of light coupled to the semiconductor element. When two lenses with different focal lengths are used, when fixing a lens with a long focal length, the optical coupling efficiency is deteriorated due to the deviation of the lens in the direction orthogonal to the optical axis. When the lens is used, it is small compared to the deterioration of the optical coupling efficiency due to the axial deviation of the lens. Therefore, by using the means according to the present invention, when the axial deviation occurs when fixing the lens, the decrease in the output light intensity is suppressed. Therefore, it is possible to provide an optical semiconductor module having a stable optical coupling efficiency.

  Embodiments of an optical semiconductor module and an assembly method thereof according to the present invention will be described below. In the present embodiment, two optical semiconductor elements are mounted in one module, and the two optical semiconductor elements are optically coupled using two lenses having different focal lengths. Also, when assembling the optical semiconductor module, first fix the lens with the short focal length, and then reconnect the lens with the long focal length so as to correct the axial misalignment caused when the lens with the short focal length is fixed. After adjustment, it shall be fixed.

  An optical semiconductor element, particularly a waveguide type optical semiconductor element, has substantially the same field diameter even if the type of the element is different, so that the maximum optical coupling efficiency can be obtained when the focal lengths of the two lenses are equal. If the focal lengths of the lenses are different, the optical coupling efficiency decreases. Therefore, the conventional optical semiconductor module uses two lenses having the same focal length when optically coupling two optical semiconductor elements.

  However, if two lenses with different focal lengths are used as in the present embodiment, even if an optical axis misalignment of the lens, that is, a shift in a direction perpendicular to the optical axis, occurs in the optical semiconductor module assembly, Compared with the case where two lenses having the same distance are used, there is an effect that the optical coupling efficiency is less decreased. Furthermore, since the decrease in optical coupling efficiency with respect to the axial shift amount of a lens with a long focal length is small compared to the axial shift amount of a lens with a short focal length, a lens with a long focal length is fixed after fixing a lens with a short focal length. Thereby, the fall of optical coupling efficiency can be suppressed more.

  In the optical semiconductor module of the present embodiment, when the field diameters of the two optical semiconductor elements to be mounted are substantially equal, and the amount of axial misalignment of the lens that occurs when the module is assembled is approximately the same as the field diameter of the optical semiconductor element. It is particularly effective when it is larger than.

  A typical value of the field diameter of the optical semiconductor element is about 2 μm. In particular, in the case of a waveguide type optical semiconductor element, it is about 2 μm regardless of the type of element. Therefore, in the case of waveguide type optical semiconductor elements, it can be considered that the field diameters are substantially equal. Even in the case of an optical semiconductor element other than the waveguide type, the field diameter is generally in the range of 1.0 to 2.5 μm. Even when optical semiconductor elements having field diameters falling within this range are optically coupled to each other, the field diameters fall within a substantially equal category, and the effects of the present invention are obtained.

  Even in the case of optical coupling between optical semiconductor elements having substantially the same field diameter, the effect of having a smaller field diameter is large. Therefore, the present invention is particularly effective when the axial displacement of the lens that occurs during module assembly is the same as or larger than the smaller field diameter.

  1 and 2 show a first embodiment of the present invention. As shown in FIG. 1, the optical semiconductor module according to the present embodiment includes a semiconductor laser 101 and a semiconductor optical modulator 104, which are waveguide-type optical semiconductor elements, as optical semiconductor elements mounted on a submount 105, respectively. The first lens 102 and the second lens 103 are provided so that the light emitted from the semiconductor laser 101 is coupled to the semiconductor optical modulator 104 with low loss. The first lens 102 and the second lens 103 are housed in metal cases 112 and 113, respectively.

  The first lens 102 converts the light emitted from the semiconductor laser 101 into parallel rays, and the second lens 103 collects the parallel rays and couples them to the semiconductor optical modulator 104. The positions of these lenses 102 and 103 are adjusted and then fixed on the submount 105 via the lens holder 106. At this time, the first lens 102 is first fixed, and then the second lens 103 is readjusted so as to correct the axial shift generated when the first lens 102 is fixed, and then fixed. The light emitted from the semiconductor optical modulator 104 is converted into parallel rays by the third lens 107, and the light collected by the fourth lens (not shown) is connected to an optical fiber (not shown). The third lens 107 is housed in the metal casing 117.

The first lens 102 and the second lens 103 have different focal lengths, and as shown in FIG. 2A, the focal length of the first lens 102 is f ₁ , and the second lens Assuming that the focal length of 103 is f ₂ (f ₂ ≠ f ₁ ), an image of light emitted from the semiconductor laser 101 and condensed on the input optical waveguide of the semiconductor optical modulator 104 via the two lenses 102 and 103. The magnification is f ₂ / f ₁ . Therefore, when the focal length f ₁ is smaller than the focal length f ₂ , the diameter of the light field 111 at the incident end of the semiconductor optical modulator 104 is f of the diameter of the light field 110 at the outgoing end of the semiconductor laser 101. ₂ / f Enlarged by ₁ times.

  In addition, since the field diameter of the light of the semiconductor element is substantially the same for all kinds of elements, the diameter of the field 110 of the semiconductor laser 101 and the diameter of the field 112 of the semiconductor optical modulator 104 are substantially equal. To do.

  FIG. 2B shows an example of the enlarged light field 111 and the light field 112 of the semiconductor optical modulator 104. The optical coupling efficiency is expressed by an overlap integral of the expanded light field 111 and the light field 112 of the semiconductor optical modulator 104. Therefore, the optical coupling efficiency in the present embodiment is lower than the optical coupling efficiency when the light fields having the same size are overlapped, but the axial deviation that occurs in the direction indicated by the arrow in the drawing of the second lens 103, that is, The amount of change in the optical coupling efficiency due to the axial shift that occurs in the direction perpendicular to the optical axis is small.

  For this reason, when an axial deviation occurs when the lens is fixed, the first lens 102 and the second lens 103 having different focal lengths are used to reduce a decrease in optical coupling efficiency due to the axial deviation. It is easy to keep the amount of change within a certain value.

  Therefore, according to the present embodiment, it is possible to suppress the change of the optical coupling efficiency even when the lens is misaligned during the assembly of the optical semiconductor module, and to produce the optical semiconductor module having a stable optical coupling efficiency. did it.

  3 and 4 show a second embodiment of the present invention. As shown in FIG. 3, the optical semiconductor module according to the present embodiment includes a semiconductor laser 201 and a semiconductor optical modulator 204 each of which is a waveguide type optical semiconductor element mounted on a submount 205. The first lens 202 and the second lens 203 are provided so that the light emitted from the light is coupled to the semiconductor optical modulator 204 with low loss. The first lens 202 and the second lens 203 are housed in metal cases 212 and 213, respectively.

  The first lens 202 converts the light emitted from the semiconductor laser 201 into parallel rays, and the second lens 203 collects the parallel rays and couples them to the semiconductor optical modulator 204. The positions of these lenses 202 and 203 are adjusted and then fixed on the submount 205 via the lens holder 206. At this time, first, the second lens 203 is fixed, and then the first lens 202 is readjusted so as to correct the axial shift generated when the second lens 203 is fixed, and then fixed. The light emitted from the semiconductor optical modulator 204 is converted into parallel light by the third lens 207, and the light condensed by the fourth lens (not shown) is connected to an optical fiber (not shown). The third lens 207 is housed in a metal housing 217.

Here, it is assumed that the first lens 202 and the second lens 203 have different focal lengths, and the focal length of the first lens 202 is f ₁ , as shown in FIG. the focal length of 203 and f _2. When the field shape of the light is traced from the semiconductor optical modulator 204 in the direction opposite to the traveling direction of the light, the image magnification of the light coupled to the output optical waveguide of the semiconductor laser 201 via the two lenses 202 and 203 is f ₁ / f Become ₂ . Therefore, when the focal length f ₁ is larger than the focal length f ₂ , the diameter of the light field 211 at the emission end of the semiconductor laser 201 is f ₁ / f ₂ of the diameter of the light field 210 of the semiconductor optical modulator 204. Doubled.

  In addition, since the field diameter of light of the optical semiconductor element is substantially the same for all types of elements, the diameter of the field 210 of the semiconductor laser 201 and the diameter of the field 212 of the semiconductor laser 201 are substantially equal. .

  FIG. 4B shows an example of the enlarged light field 211 and the light field 212 of the semiconductor laser 201. The optical coupling efficiency is expressed by an overlap integral between the expanded light field 211 and the light field 212 of the semiconductor laser 201. The optical coupling efficiency in the present embodiment is lower than the optical coupling efficiency when the light fields of the same size are overlapped, but the axial displacement generated in the direction indicated by the arrow of the first lens 202, that is, the light The amount of change in the optical coupling efficiency due to the axial shift that occurs in the direction perpendicular to the axis is reduced. For this reason, when an axial shift occurs when the lens is fixed, a decrease in optical coupling efficiency due to the axial shift can be reduced, and the amount of change can be easily kept within a certain value.

  Therefore, according to the present embodiment, it is possible to suppress the change of the optical coupling efficiency even when the lens is misaligned during the assembly of the optical semiconductor module, and to produce the optical semiconductor module having a stable optical coupling efficiency. did it.

The third embodiment of the present invention will be shown below. In the present embodiment, the embodiment described in the first embodiment will be described as an example.
The optical semiconductor module according to the present embodiment is applied to the configuration shown in FIGS. 1 and 2, and includes a semiconductor laser 101 and a semiconductor optical modulator 104, each of which is a waveguide type optical semiconductor element mounted on a submount 105. The first lens 102 and the second lens 103 are provided so that the light emitted from the semiconductor laser 101 is adjusted to be coupled to the semiconductor optical modulator 104 with low loss. Then, after the positions of the lenses 102 and 103 are adjusted, the first lens 102 and the second lens 103 are fixed on the submount 105 via the lens holder 106 by YAG laser welding in this order. At this time, the first lens 102 is first fixed, and then the second lens 103 is readjusted so as to correct the axial shift generated when the first lens 102 is fixed, and then fixed.

The first lens 102 and the second lens 103 have different focal lengths, and the focal length of the first lens 102 is f ₁ and the focal length of the second lens 103 is f ₂ . Then, the image magnification of the light emitted from the semiconductor laser 101 and condensed on the input optical waveguide of the semiconductor optical modulator 104 is f ₂ / f ₁ . Therefore, when the focal length f ₁ is smaller than the focal length f ₂ , the diameter of the light field diameter 111 at the incident end of the semiconductor optical modulator 104 is equal to the diameter of the light field 110 at the outgoing end of the semiconductor laser 101. It is expanded to f ₂ / f ₁ times.

  In addition, since the field diameter of the light of the semiconductor element is substantially the same for all kinds of elements, the diameter of the field 110 of the semiconductor laser 101 and the diameter of the field 112 of the semiconductor optical modulator 104 are substantially equal. To do.

  The optical coupling efficiency is expressed by the overlap integral of the expanded light field 111 and the light field 112 of the semiconductor optical modulator 104. Therefore, the optical coupling efficiency in the present embodiment is the same magnitude light field. However, the amount of change in the optical coupling efficiency due to the axial displacement of the second lens 103 is small.

FIG. 3 shows the result of calculating the coupling loss change with respect to the axial displacement of the second lens 103 in the direction orthogonal to the optical axis. The ratios of the focal lengths f ₁ and f ₂ of the lens are five cases of f ₁ : f ₂ = 1: 1, 1: 1.5, 1: 2, 1: 2.5, 1: 3. Calculated.

  For example, when the lens is fixed by YAG laser welding when assembling the optical semiconductor module, the axial displacement of the lens is about several μm (5 to 8 μm depending on conditions). The amount of deviation can be minimized by offsetting the lens position opposite to the contraction direction (the direction of deviation) before welding, but it is difficult to correct variations in the amount of deviation. . The variation in the amount of deviation is about 1.0 to 2.5 μm.

From FIG. 5, when the axis shift amount of the second lens 103 is 1.0μm or more, the focal length f ₁ and f ratio of ₂ f _1: f ₂ = 1: than that of 1, f _1: f _It can be seen that when ₂ = 1: 1.5, the reduction in coupling loss is smaller with respect to the axial displacement of the second lens 103. Further, if the axial shift amount of the second lens 103 is 2.5μm or less, the focal length f ₁ and f ratio of ₂ f _1: f ₂ = 1: than that of 3, f _1: f ₂ = It can be seen that the reduction in coupling loss is smaller with respect to the axial displacement of the second lens 103 in the case of 1: 2.5.

As described above, by setting the ratio of the focal lengths f ₁ and f ₂ of the first lens 102 and the second lens 103 to 1: 1.5 to 1: 2.5, two focal lengths are equal. Compared to using two lenses, it is possible to further reduce the decrease in optical coupling efficiency due to the axial misalignment of the lens when an axial misalignment occurs when the lens is fixed, and to easily keep the amount of change within a certain value. become.

  Therefore, according to the present embodiment, it is possible to suppress the change of the optical coupling efficiency even when the lens is misaligned during the assembly of the optical semiconductor module, and to produce the optical semiconductor module having a stable optical coupling efficiency. did it.

A fourth embodiment of the present invention will be described below. The present embodiment is applied to the forms described in the first to third embodiments. Hereinafter, Example 1 will be described as an example.
As shown in FIGS. 1 and 2, the optical semiconductor module according to the present embodiment includes a semiconductor laser 101 and a semiconductor optical modulator 104, which are waveguide-type optical semiconductor elements, mounted on a submount 105, respectively. A first lens 102 and a second lens 103 are provided, the positions of which are adjusted so that light emitted from the semiconductor laser 101 is coupled to the semiconductor optical modulator 104 with low loss. After the positions of the lenses 102 and 103 are adjusted, the lenses 102 and 103 are fixed on the submount 105 via the lens holder 106. The first lens 102 and the second lens 103 have different focal lengths, and the focal length of the first lens 102 is f ₁ and the focal length of the second lens 103 is f ₂ .

FIG. 6 shows a second case where the first lens 102 is fixed first, and then the second lens 103 is readjusted and fixed so as to correct the axial misalignment caused when the first lens 102 is fixed. 6 is a graph showing a change in coupling loss with respect to the amount of axial displacement of the lens 103. FIG. 6 shows the calculation results for three cases in which the ratio of the focal lengths f ₁ and f ₂ of the first and second lenses is f ₁ : f ₂ = 1: 1, 1: 2, 2: 1. is there.

When a lens with a short focal length is used as the first lens 102 and a lens with a long focal length is used as the second lens 103 (f ₁ : f ₂ = 1: 2), the amount of axial displacement of the second lens 103 6 changes as shown by a solid line in FIG. 6, and when the axial displacement amount of the second lens 103 is 1.2 μm or more, the focal length shown by the broken line in FIG. Compared with the case of f ₁ : f ₂ = 1: 1), the coupling loss is small.

On the other hand, when a lens having a long focal length is used as the first lens 102 and a lens having a short focal length is used as the second lens 103 (f ₁ : f ₂ = 2: 1), the axis of the second lens 103 is used. The coupling loss with respect to the deviation amount changes as indicated by a dotted line in FIG. 6, and the coupling loss increases with respect to the axial deviation amount.

  That is, when optical coupling between semiconductor elements is performed using two lenses having different focal lengths, the optical coupling efficiency greatly decreases with respect to the amount of axial deviation of a lens with a short focal length, and the axial deviation of a lens with a long focal length. It can be seen that the decrease in the optical coupling efficiency with respect to the amount is small. In the configuration of Example 2 shown in FIG. 3, after the second lens 203 with a short focal length is fixed, the first lens 202 with a long focal length is displaced by the axial deviation that occurs when the second lens 203 is fixed. When readjusted to be corrected and fixed, the change in the optical coupling efficiency with respect to the axial deviation of the first lens 202 having a long focal length is the same as the calculation result shown by the solid line in FIG.

  Therefore, when fixing the two lenses, after bringing the lens to the optimum coupling position by adjusting the position of the lens, first fix the lens with a short focal length, and the axis generated when fixing the lens with a short focal length. After adjusting the lens with a long focal length to correct the misalignment, the lens with a long focal length is fixed, so that the optical coupling efficiency can be achieved even when the lens is misaligned during assembly of the optical semiconductor module. Can be produced, and an optical semiconductor module with stable optical coupling efficiency can be manufactured.

  The present invention relates to an optical semiconductor module and an assembling method thereof, and more specifically, can be used for mounting an optical semiconductor device used in an optical communication system or an optical information processing system.

It is a schematic block diagram which shows typically the structure of Example 1 of this invention. FIG. 2A is a schematic diagram showing the relationship between the configuration and the light field in Example 1 of the present invention, and FIG. 2B is a graph showing the light field. It is a schematic block diagram which shows typically the structure of Example 2 of this invention. FIG. 4A is a schematic diagram showing the relationship between the configuration and the light field in Example 1 of the present invention, and FIG. 4B is a graph showing the light field. It is a graph which shows the change of the optical coupling loss by Example 3 of this invention. It is a graph which shows the change of the optical coupling loss by Example 4 of this invention.

Explanation of symbols

101, 201 Semiconductor laser 102, 202 First lens 103, 203 Second lens 104, 204 Semiconductor optical modulator 105, 205 Submount 106, 206 Lens holder 110, 212 Field of light at the semiconductor laser emitting end 111 Lens Field of light of semiconductor laser converted by magnification 112, 210 Field of light at incident end of semiconductor optical modulator 211 Field of light of semiconductor optical modulator converted by magnification by lens

Claims (7)

  A first optical semiconductor element; a first lens that collimates light emitted from the first optical semiconductor element; a second lens that condenses the parallel light; and the second lens. In the optical semiconductor module in which the second optical semiconductor element arranged at a position where the condensed light is coupled to the optical waveguide is mounted on a common submount, the focal length of the first lens and the second lens The optical semiconductor modules are characterized in that their focal lengths are different from each other.   2. The optical semiconductor module according to claim 1, wherein a field diameter of the first optical semiconductor element and a field diameter of the second optical semiconductor element are substantially equal.   3. The optical semiconductor module according to claim 1, wherein an axial displacement amount of the lens generated during assembly is the same as or smaller than a small field diameter of the field diameters of the first and second optical semiconductor elements. An optical semiconductor module characterized by being large.   4. The optical semiconductor module according to claim 1, wherein a ratio of focal lengths of the two lenses is 1: 1.5 or more and 1: 2.5 or less and an image magnification of 1.5. An optical semiconductor module characterized in that an optical system of at least twice and at most 2.5 times is formed.   5. A method of assembling the optical semiconductor module according to claim 1, wherein the metal housing accommodating the lens is fixed onto the submount through a lens holder by YAG laser welding. A method of assembling an optical semiconductor module.   5. A method of assembling the optical semiconductor module according to claim 1, wherein the two optical semiconductor elements are fixed on the submount, the position of the lens is adjusted, and a focal length of the optical semiconductor module is adjusted. When fixing the different first lens and the second lens, a lens having a short focal length is first fixed on the submount, and a lens having a long focal length is fixed on the submount later. Assembling method of optical semiconductor module.   7. An optical semiconductor module manufactured by the method for assembling an optical semiconductor module according to claim 5.

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