JPH10247741A - Light emitting module for optical communication and method of assembling the same - Google Patents

Abstract

(57) [Problem] To incorporate a light transmitting unit including a LD, an LD driver IC, etc., an optical system unit, a heat radiating member, etc. in a module, and to perform a sequential assembly including a centering process. Realize the structure. An optical system unit includes a lens, a lens holder, a sleeve, and a ferrule stopper. The light transmission unit is an LD, submount, heat dissipation member, LD
It comprises a driver IC, a PD for monitoring the output light of the LD, a subcarrier, a substrate having external wiring and passive components, a heat sink, and a metal package used as a radiation fin. Metal package and optical system unit,
The metal package and the receptacle unit, and the metal package and the outer case are mechanically and thermally connected by resin or solder, respectively, and each part in the light transmitting unit is electrically connected by wire bonding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small-sized and low-power light-emitting module for optical communication having a built-in driver and used as an optical transmitter for an ultra-high-speed optical transmission system.

[0002]

2. Description of the Related Art FIG. 8 shows a configuration of a conventional light emitting module for optical communication. In the figure, 41 is a butterfly type package, 42 is a gold-plated spherical optical fiber, 43 is an optical fiber fixing substrate, and 1 is a semiconductor laser (hereinafter referred to as “L”).
D "), 2 is a submount for mounting the LD1, 3
Denotes a Peltier element module, 5 denotes a photodiode (hereinafter referred to as “PD”) for monitoring the output light of the LD 1, and 6 denotes a subcarrier on which the PD 5 is mounted. In this assembling method, the LD 1 is made to emit light, the light is received by the spherical optical fiber 42, the spherical optical fiber 42 is fixed to the optical fiber fixing substrate 43 while aligning, and the spherical optical fiber 4 is further fixed.
2 was sealed in a package 41 with solder.

In order to attach an optical isolator to this unit, as shown in FIG. 9, a polarizer 5 is provided between two pairs of optical systems each having an optical fiber 51 and a lens 52 combined.
It is necessary to insert the optical isolator 22 including the Faraday element 3 and the Faraday element 54 and adjust the optical axes of the two pairs of optical systems. As described above, in the conventional light emitting module for optical communication, the alignment of the spherical optical fiber 42 and the alignment of the optical isolator 22 are required twice (problem 1). Also,
The centering of the spherical optical fiber 42 has to be performed in the small package 41, and the centering operation is troublesome (problem 2). Further, since the optical fiber fixing substrate 43, the submount 2, and the subcarrier 6 are mounted on the same Peltier device module 3, the size of the Peltier device module 3 cannot be reduced, and the size and power consumption are reduced. Was difficult to reduce (problem 3). Further, since the alignment operation is required and the spherical optical fiber 42
The need for solder fixation has been a major obstacle to mass production of light emitting modules for optical communication.

In order to solve these problems, a surface mounting module using a sequential assembly method has been devised. FIG.
The structure of a conventional surface mount module is shown below (95,
C-184). In the figure, 61 is a package, 62 is an optical fiber fixing substrate, 63 is a subcarrier, 64 is an optical fiber terminal, 65 is an optical fiber holder, 66 is a fixing block, and 67 is an outer lid. The assembly method is L
D is mounted on the optical fiber fixing substrate 62, this is mounted on the package 61, the PD is mounted on the subcarrier 63, this is mounted on the package 61, and the optical fiber terminal 64 is mounted on the optical fiber fixing substrate 62. The optical fiber press 65 is used for fixing, the outer cover 67 is attached, and the fixing block 66 is attached.

[0005]

However, in the configuration of the conventional surface mount module, the optical coupling loss is large because the module is mounted without centering (problem 4). Also, since the mounted component is a single component such as an LD, and is not configured to include an LD driver IC or the like, it is unsuitable for increasing the functionality and speed of the module (problem 5).

In a light emitting module for optical communication,
In the case where a Peltier element is incorporated for stabilizing the temperature of the LD, the following problem occurs. Conventionally, an LD module sold as a submount type is shown in FIG.
As shown in FIG.
2 has a structure in which the LD 1 is mounted. Further, as shown in FIG.
A metallization 83 is sandwiched between the ceramic substrate 81 and the Peltier element 82, and the other surface of the ceramic substrate 81 is soldered 84
Had become.

When a light emitting module for optical communication is constructed by using these, it is required to improve the heat conduction as much as possible in order to enhance the heat absorbing effect of the Peltier element module. In order to improve the reliability by reducing the mechanical stress, it is desirable that the thermal expansion coefficient of each member and the LD be as close as possible. In addition, the reliability of the Peltier element module itself is highly dependent on mechanical stress due to heat.

However, in the conventional structure, LD1 and Si
Although the thermal expansion coefficient of C72 was almost the same, the thermal expansion coefficient of the metal submount 71 was large.
Further, the thermal expansion coefficient of alumina (Al ₂ O ₃ ) of the ceramic substrate 81 used in the conventional Peltier device module is not only larger than the thermal expansion coefficient of the LD 1 but also the thermal conductivity is 20 to 30 W /. m · K, which is one digit smaller than that of SiC 72 or metal submount 71. Further, the materials and the like used for the conventional heat sink are not selected from such a viewpoint.

For this reason, the conventional parts cannot effectively draw out the heat absorbing effect of the Peltier element module (problem 6). In addition, the reliability of the LD and the Peltier element module cannot be designed in terms of the thermal expansion coefficient. The present invention has a small and low power consumption in which a light transmitting unit including an LD, an LD driver IC, and the like are incorporated in a module, an optical system unit, a heat radiation member, and the like, and can be sequentially assembled including an alignment process. It is an object of the present invention to provide a light emitting module for optical communication having a built-in driver and an assembling method thereof.

[0010]

The light emitting module for optical communication according to the present invention comprises a receptacle unit, an optical system unit, and a light transmitting unit. The receptacle unit includes a resin sleeve insertion case and a resin adapter. The optical system unit includes a lens, a lens holder, a sleeve, and a ferrule stopper. The light transmitting unit includes a light transmitting element unit and a light transmitting circuit unit. The light transmitting element unit is L
D, a submount for mounting the LD, and a heat dissipating member that also serves to adjust the position of the LD and dissipate heat. The light transmission circuit unit includes an LD driver IC for driving the LD, a PD for monitoring the output light of the LD, a subcarrier for mounting the PD,
It is composed of a substrate having external wiring and passive components, a heat sink and a metal package used as a radiation fin. The metal package and the optical system unit, the metal package and the receptacle unit, the metal package and the outer case are mechanically and thermally connected by resin or solder, respectively, and the respective parts in the light transmitting unit are electrically connected by wire bonding. .

[0011]

1 and 2 show an embodiment of a light emitting module for optical communication according to the present invention. FIG. 1 shows a cross-sectional configuration of the entire module viewed from the side, and FIG. 2 shows a planar configuration of the light transmitting unit and the optical system unit when viewed from above. 1 and 2, the light transmitting unit is an LD.
1. Submount 2 for mounting LD1, Peltier element module 3 (above, light transmitting element unit), subcarrier 6 for mounting LD driver IC 4, PD5, PD5, substrate 9 having metallized wiring 7, thermistor 8, etc., heat sink And a metal package 10 (above, a light transmission circuit unit) used as a radiation fin. The outer case 11 is attached to the light transmitting unit. The optical system unit includes a lens 21, an optical isolator 22, a lens holder 23, and a sleeve 24. The receptacle unit includes a sleeve insertion case 31 made of resin and an adapter part 32 made of resin.

The LD 1 is mounted on the rear end of the Peltier element module 3 together with the concave submount 2.
The lens 2 of the optical system unit is
1 is arranged so as to come to the front of LD1. The PD 5 is mounted on the subcarrier 6 and is directly mounted on the metal package 10 behind the LD 1 together with the LD driver IC 4. The LD 1 and the LD driver IC 4, and the LD driver IC 4 and the metallized wiring 7 on the substrate 9 are directly connected via bonding wires 12.

In the light-emitting module for optical communication according to the present invention, a powder-molded component that can be manufactured at low cost and with high dimensional accuracy is used as the metal package 10. In this powder molding, the shape can be freely set, so that the radiation fins can be easily formed.
The heat generated by the D driver IC 4 and the like can be efficiently dissipated, and is suitable for dissipating the heat absorbed by the Peltier element module 3 (Solution 6). Further, since the heat generating portion such as the LD driver IC 4 and the like can be thermally separated from the LD 1 and the Peltier element module 3 only needs to control the temperature of the LD 1, its size can be reduced and power consumption can be reduced. Can be reduced (solution of problem 3). Further, by using Cu / W (copper-tungsten) as a material, it becomes possible to reduce the thermal resistance and adjust the thermal expansion coefficient (the details will be described later).

In the light emitting module for optical communication of the present invention, a powder molded component is used as the subcarrier 6 on which the PD 5 is mounted. The PD 5 needs to be set at a predetermined angle with respect to the LD 1, and the mounting surface of the subcarrier 6 can be easily inclined by powder molding. The Peltier element module 3 is necessary for controlling the temperature of the LD 1, but may be replaced with a Cu / W substrate having the same thickness as the Peltier element module 3 if there is no requirement.

The optical system unit includes a lens 21, an optical isolator 22, a lens holder 23 composed of a part for fixing the lens 21, and a part for a ferrule stopper.
The sleeve 24 is integrated. Therefore, alignment is
Since the alignment can be performed with the optical fiber ferrule inserted into the sleeve 24, the alignment work becomes extremely easy (solution of the problems 1, 2, 4). In a short-distance system or the like in which light reflection is suppressed to be low in the entire system, the optical isolator 22 is not required.
In that case, a structure in which this is omitted may be adopted.

The LD driver IC 4 is a metal package 1
0 or the substrate 9, but here, the heat radiation effect is enhanced by directly attaching to the metal package 10. If it is not desired to take the ground potential as the substrate potential of the LD driver IC 4, the substrate may not be directly attached to the metal package 10 but may be attached via an AlN (aluminum nitride) substrate, for example. Since the LD driver IC 4 and LD 1 are directly connected via the bonding wire 12, the inductance between them can be reduced, and high-speed operation can be performed (solution of problem 5).

FIG. 3 shows an assembly procedure of the light emitting module for optical communication according to the present invention. The LD 1 and the thermistor 8 are mounted on the submount 2 and mounted on the Peltier element module 3 to assemble the light transmitting element unit. The PD 5 is die-bonded to the subcarrier 6 and electrically connected to the metallized wiring portion of the subcarrier 6 by wire bonding.

A passive element such as a capacitor (not shown) is mounted on the substrate 9. The LD driver IC 4, the subcarrier 6, and the substrate 9 are mounted on the metal package 10, and the light transmission circuit unit is assembled. After attaching the Peltier element module 3 to the metal package 10 by soldering, wiring is performed, and the outer case 1
Cover with 1 and assemble the light transmission unit.

A light transmitting unit and an optical system unit (2
The two units (1, 22, 23, 24) are aligned and fixed with resin. The receptacle unit (31, 32) is placed over the sleeve portion of the unit fixed and aligned, and attached to the metal package 10 to complete the light emitting module for optical communication.

Here, features of the light emitting module for optical communication of the present invention will be described. (First feature) The first feature is that an optical axis shift due to a difference in the thermal expansion coefficient between the metal package and the Peltier element module can be dealt with.

In the conventional module, the spherical optical fiber and the LD are on the same Peltier element module, and the mechanical deformation accompanying the thermal expansion of the Peltier element module occurs in the same direction with respect to both, and the optical axis shift is caused. There was no problem. However, in the present invention, since the LD 1 is on the Peltier element module 3 and the optical system unit is on the metal package 10, there is a problem of optical axis shift due to a difference in thermal expansion coefficient.

In the present embodiment, in order to improve the heat absorption efficiency of the Peltier device module 3, the thermal expansion coefficient of the
An AlN substrate is used as the ceramic substrate 81 of the Peltier element module 3 to improve reliability in accordance with the thermal expansion coefficients of the submount 1 and the submount 2. Further, as shown in FIG. 4, metallization Ni 83-1 and metallization Cu 83-2 are used as metallization 83 between ceramic substrate 81 and Peltier element 82. The solder 1 for attaching the submount 2 to the ceramic substrate 81 is designated as 84-1 and the solder 2 for the other ceramic substrate 81 is designated as 84-2.

Table 1 shows the coefficient of thermal expansion of each part in this configuration. Note that (× 2) indicates that there are two sheets, but one does not have thermal expansion because the temperature is controlled.

[0024]

[Table 1]

As can be seen from this table, when a metal package is prepared using a typical Cu / W material having a conventional coefficient of thermal expansion of 1 × 10 ⁻⁵ / K, the difference from the average coefficient of thermal expansion of the Peltier element module is obtained. Is 5.2 × 10 ⁻⁶ / K. This means that the displacement between the position of the LD mounted on the submount and the position of the optical system unit mounted on the metal package occurs at a rate of 5.2 × 10 ⁻⁶ / K with respect to the temperature. In the present embodiment, since the length from the heat radiation side surface of the Peltier element module to the light emitting part of the LD is about 3 mm, the ratio of the positional deviation to the temperature is 1.5 × 10 ⁻² μm / K.
Thus, a displacement of about 0.45 μm occurs for a temperature change of 30 ° C. This is a large value with respect to the tolerance of the alignment of the single mode optical fiber and the LD (normally, ± 1 dB to suppress the change of the optical coupling efficiency to within ± 1 dB).
It is necessary to fix the position to 0.5 μm or less), and it is necessary to further reduce the displacement due to the difference in the coefficient of thermal expansion.

Therefore, in the present embodiment, a method of changing the mixing ratio of Cu / W to match the average thermal expansion coefficient of 4.8 × 10 ⁻⁶ / K shown in Table 1 is used, and while maintaining the heat radiation efficiency, the LD, The thermal expansion coefficients of the mount and the Peltier element module are matched to prevent an optical axis shift due to a temperature change. Also,
The reliability can be improved by setting the thermal expansion coefficients of the LD, the submount, the Peltier element module, and the metal package to the same value. In addition,
The coefficient of thermal expansion shown here is in accordance with the example in Table 1, and when the setting is different from that in Table 1, the coefficient of thermal expansion to be matched also differs. In addition, Cu as a powder molding material
Although an example using / W has been described, other materials may be used as long as the coefficients of thermal expansion can be matched.

(Second Feature) A second feature is that the alignment process is simplified and wire bonding between the LD and the LD driver IC is enabled. In order to efficiently obtain the optical coupling between the LD and the optical fiber using the lens system, the LD must be placed near the lens (usually 1 mm or less). To this end, the method of arranging the LD at the end of the Peltier element module on the optical system unit side is simple, and is the best in providing a margin in the alignment process. However, in this case, the distance between the LD driver IC mounted on the metal package on the side opposite to the optical system unit side of the Peltier element module and the LD becomes longer, and direct connection of wires becomes impossible. It becomes difficult to obtain good electrical characteristics.

The structure that solves this problem is the optical system unit shown in FIG. As shown in FIG. 1, the optical system unit includes a lens 21, an optical isolator 22, a lens holder 23, and a sleeve 24. Lens holder 2
Reference numeral 3 is composed of two parts, one of which is press-fitted into the sleeve 24, and also functions as a ferrule stopper. Also, the amount of press-fit is reduced so that the ferrule is not mechanically deformed. The optical isolator 22 is housed in this component, and is integrated with the component to which the other lens 21 is fixed to form an optical system unit. Conventional modules are of the pigtail type, but in the present invention are of the receptacle type. When this unit is inserted into the receptacle unit, the light emitting module for optical communication is completed.

The feature of this optical system unit is that the sleeve 2
Since the optical fiber 4 is integrated, the position of the optical fiber is uniquely determined by the fitting of the ferrule and the sleeve, and the position of the optical isolator 22 is designed if the lens is designed so that the light flux falls within its effective area. The position adjustment of the optical isolator 22 becomes unnecessary. As described above, since the optical system is unitized, not only the alignment work is facilitated, but also the alignment work can be completed at once by adjusting the position between the unit and the LD. .

Further, by reducing the thickness of the lens supporting portion of the lens holder 23 and projecting the same, the LD 1 is connected to the Peltier element module 3 as shown in FIGS.
At the end on the LD driver IC 4 side. Since the shape of the submount 2 is concave, the protrusion of the lens holder 23 is inserted into the concave as shown in FIG. Thereby, the LD 1 and the LD driver IC 4 can be wire-bonded with the shortest distance, and the lens 21 and the LD 1 can be brought close to each other.

The lens 21 is disposed above the Peltier element module 3, and there is a problem that the alignment margin becomes small. However, the mechanical tolerance of the optical system unit,
Even if the accuracy of assembling the optical parts and the variation of the lens characteristics are considered, the variation of the focal position on the LD1 side is 100 to 200.
It can be suppressed to within μm, and about 200 μm may be considered as the alignment margin. Here, the thickness of the submount 2 is (alignment margin) + (lens holder 23).
(The thickness of the lens 21) + (the radius of the lens 21)-(the thickness up to the light emitting portion of the LD1).

(Third Feature) A third feature is that an optical axis shift caused by deformation of the metal package and the resin receptacle due to thermal expansion can be dealt with. The light emitting module for optical communication of the present invention has a receptacle structure as shown in FIG. The ferrule portion of the optical fiber connector is inserted into the sleeve 24 of the optical system unit using the receptacle unit (31, 32) as a guide. Therefore, it is necessary to position the receptacle unit and the optical system unit. On the other hand, the optical system unit is fixed to the metal package 10 after the alignment. Therefore, when the receptacle unit and the optical system unit are directly connected mechanically, thermal deformation occurs due to the difference in the thermal expansion coefficient between the resin, which is the material of the receptacle unit, and the metal package.
1 will be shifted from the optical axis. In particular, the coefficient of thermal expansion of resin is higher than that of metal packages,
Further, since the metal package and the receptacle unit are fixed, a bimetal phenomenon occurs, and its thermal deformation cannot be ignored.

A structure that solves this problem is the receptacle unit shown in FIG. As shown in FIG. 1, the receptacle unit includes a sleeve insertion case 31 made of resin and an adapter part 32 made of resin. It is designed so that a gap of 2 to 45 μm is opened between the sleeve insertion case 31 and the sleeve 24. The minimum value is a value that can absorb deformation due to thermal expansion, and the maximum value is determined as an allowable value for the ferrule to be smoothly inserted into the sleeve 24.

Deformation due to thermal expansion can be at most about 1 μm. However, in the optical coupling of the LD, even about half of this value causes a loss of -1 dB and cannot be ignored. Therefore, if a gap of at least about 2 μm is provided, the effect can be expected sufficiently. On the other hand, if the gap is too wide, on the other hand, the positioning effect between the receptacle unit and the optical system unit is lost, and in the worst case, the ferrule cannot be inserted. The ferrule is inserted using the ferrule insertion side tapered portion 33 of the sleeve insertion case 31 as a guide, and the margin of the inner diameter of the guide portion with respect to the ferrule diameter is ± 45 μm at the worst value.
Therefore, if the maximum value of the gap between the sleeve insertion case 31 and the sleeve 24 is set to 45 μm or less, the center position deviation between the ferrule insertion side tapered portion 33 and the inserted sleeve 24 becomes within 45 μm, and the ferrule is formed by the taper. It can be smoothly inserted into the sleeve 24.

(Fourth feature) The fourth feature is that the displacement of the optical system unit that occurs when the optical system unit is attached can be eliminated. When the optical system unit is mounted, alignment of three axes in two directions (x and y directions) perpendicular to the optical axis and in the optical axis direction (z direction) is performed. It is uncertain for the alignment margin. In the x and y directions, the receptacle unit may be shifted to a position corresponding to the optical system unit and attached to the metal package. However, the receptacle unit and the metal package are bonded in a plane perpendicular to the z-axis, and there is no tolerance in the z-direction.

The structure that solves this problem is the receptacle unit shown in FIG. Optical unit sleeve 2
By making the sleeve insertion case 31 into which the cartridge 4 is inserted longer, and making a gap also in the z direction, the displacement of the optical system unit in the z direction is absorbed.

[0037]

As described above, the light emitting module for optical communication of the present invention has a structure in which the optical axis can be easily adjusted by a single adjustment of the optical axis, and a structure capable of coping with the optical axis deviation due to thermal expansion. Have. Further, direct connection between the LD and the LD driver IC is possible. In addition, it is possible to absorb the displacement of the fixed position which occurs due to the alignment process of absorbing the optical focus variation of the optical system unit. Therefore, small,
A high-speed, low-power-consumption, low-cost light-emitting module for optical communication can be realized.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a light emitting module for optical communication of the present invention.

FIG. 2 is a plan view showing an embodiment of the light emitting module for optical communication of the present invention.

FIG. 3 is a diagram showing an assembling procedure of the light emitting module for optical communication of the present invention.

FIG. 4 is a diagram showing a configuration of a Peltier element module 3;

FIG. 5 is a diagram showing a configuration of an optical system unit.

FIG. 6 is a diagram showing a configuration of a receptacle unit.

FIG. 7 is a diagram showing a configuration of a receptacle unit.

FIG. 8 is a diagram showing a configuration of a conventional light emitting module for optical communication.

FIG. 9 is a diagram illustrating a method of attaching an optical isolator.

FIG. 10 is a diagram showing a configuration of a conventional surface mount module.

FIG. 11 is a diagram showing a configuration of a conventional LD module.

FIG. 12 is a diagram showing a configuration of a conventional Peltier element module.

[Explanation of symbols]

 Reference Signs List 1 semiconductor laser (LD) 2 submount 3 Peltier device module 4 LD driver IC 5 photodiode (PD) 6 subcarrier 7 metallization wiring 8 thermistor 9 substrate 10 metal package 11 outer case 12 bonding wire 21 lens 22 optical isolator 23 lens holder 24 Sleeve 31 Sleeve insertion case 32 Adapter part 33 Ferrule insertion side taper part

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yoshihisa Strashina, 1126 Nomachi, Hamamatsu-shi, Shizuoka Prefecture Inside Hamamatsu Photonics Co., Ltd. Inside the corporation

Claims (11)

[Claims] 1. A semiconductor laser, a semiconductor laser, and a receptacle unit including a resin sleeve insertion case and a resin adapter unit, an optical system unit including a lens, a lens holder, a sleeve, and a ferrule stopper. Submount,
A heat dissipating member that combines position adjustment and heat dissipation of the semiconductor laser,
It is composed of a semiconductor laser driver IC for driving a semiconductor laser, a photodiode for monitoring the output light of the semiconductor laser, a subcarrier for mounting the photodiode, a substrate having external wiring and passive components, and a metal package used as a heat sink and a radiation fin. The metal package and the optical system unit, the metal package and the receptacle unit, the metal package and the outer case are mechanically and thermally connected by resin or solder, respectively, and the light transmission unit is provided. A light emitting module for optical communication, wherein each part in the unit is electrically connected by wire bonding. 2. The light-emitting module for optical communication according to claim 1, wherein the receptacle unit and the optical system unit are separated from each other and connected to a metal package, respectively, and the receptacle unit and the optical system unit are connected to a metal package. A light emitting module for optical communication, wherein a gap of 2 μm or more and 45 μm or less is provided between them. 3. The light emitting module for optical communication according to claim 1, wherein AlN or thermal expansion is used as a material of a submount for mounting a semiconductor laser constituting a light transmitting unit, a heat radiation member, and a metal package. A light emitting module for optical communication, characterized by using Cu / W whose coefficient of mixing is adjusted so that the difference is 1 × 10 ⁻⁶ / K or less with respect to the coefficient of thermal expansion of a semiconductor laser. 4. The light emitting module for optical communication according to claim 3, wherein AlN or Cu / W is used as a material of a subcarrier for mounting a photodiode constituting the light transmitting unit. Light emitting module. 5. The light emitting module for optical communication according to claim 1, wherein a Peltier element module including an AlN substrate, a metallized Cu, a metallized Ni, and a Peltier element is used as the heat radiation member. Characteristic light-emitting module for optical communication. 6. The light emitting module for optical communication according to claim 5, wherein the material of the metal package forming the light transmitting unit is:
An optical communication light emitting module using Cu / W whose mixing ratio is adjusted so that the coefficient of thermal expansion becomes equal to the average coefficient of thermal expansion of the Peltier element module. 7. The light emitting module for optical communication according to claim 1, wherein an optical isolator is built in the optical system unit. 8. The optical communication module according to claim 7, wherein the optical system unit has a lens, an optical isolator, a lens holder, and a sleeve integrated with each other and is of a receptacle type. Light emitting module. 9. The light emitting module for optical communication according to claim 1, wherein the submount for mounting the semiconductor laser has a concave shape, and the lens holder of the optical system unit is a lens support. A light emitting module for optical communication, characterized in that the thickness of the lens is thin and has a protruding shape, and the protrusion of the lens holder is inserted into a recess of the submount. 10. The light emitting module for optical communication according to claim 1, wherein the thickness of the submount on which the semiconductor laser is mounted is (thickness of lens holder) + (radius of lens). -A light emitting module for optical communication, characterized in that the thickness is set to (thickness up to the light emitting portion of the semiconductor laser) plus an alignment margin of about 200 µm. 11. The method for assembling a light emitting module for optical communication according to claim 1, wherein the step of fitting the sleeve insertion case and the adapter unit to assemble the receptacle unit, the lens, the ferrule stopper, and the sleeve in the lens holder. To assemble the optical system unit by inserting and fixing with a resin or press-fitting, attaching the semiconductor laser to the submount, and assembling the light-sending element unit by attaching the submount to the heat dissipation member. Assembling a light transmitting circuit system unit by attaching a subcarrier and a semiconductor laser driver IC; fixing the light transmitting element unit and the light transmitting circuit system unit with solder or resin; Other wire bondin Assembling the light transmitting unit by electrically connecting the light transmitting unit with the optical system unit, aligning the optical axis with the optical system unit, and fixing the resin, and fixing the light transmitting unit and the receptacle unit with the resin. And a step of assembling the light emitting module for optical communication.