JPH11354890A - Semiconductor laser module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize the oscillation characteristics of a semiconductor laser element by improving the cooling capacity of a semiconductor laser module with the electronic cooling device of a two-stage configuration. SOLUTION: A first-stage electron-cooling element 11 and a second-stage electronic cooling element 12 are overlapped to form electronic cooling equipment 6. An optical part with a large thermal capacity consisting of a first lens 2 and a photodetector 7 is mounted to the first stage via a carrier 32, and a semiconductor laser element 1 and a thermistor 8 requiring precise temperature control are mounted to the second stage. An opening 51, where the second- stage electronic cooling element 12 passes, is provided at the center of the carrier 32, and the opening is formed in a fitting structure with the second-stage electronic cooling element, thus preventing the shifting of the carrier 32.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser module used as a light source for optical communication, and more particularly to a semiconductor laser module having a built-in thermoelectric cooler.

[0002]

2. Description of the Related Art In a semiconductor laser module used as a light source in an optical communication system, the light output sharply decreases or deteriorates as the temperature rises, and the oscillation characteristics of the semiconductor laser element change due to a change in ambient temperature. Therefore, when the semiconductor laser device is used as a light source in an optical communication system, these reductions in optical output and changes in oscillation characteristics greatly affect transmission characteristics.

Recently, in optical communication, wavelength division multiplexing (WD)
M) The adoption of the transmission method has increased the density of the optical communication transmission method, and accordingly, it has become necessary to increase the output of the semiconductor laser module for excitation used in the optical fiber amplifier. In order to increase the output of the semiconductor laser module for excitation, it is necessary to improve the element output and the coupling efficiency.
Accordingly, it is necessary to improve the cooling capacity of the semiconductor laser module.

In order to solve the above-described problem of cooling the semiconductor laser module, a method of controlling a semiconductor laser element and a laser light monitor element at a constant temperature by incorporating an electronic cooling element in a package of the semiconductor laser module has been proposed. Has been adopted. That is, as shown in FIG. 3, a semiconductor laser element 121, a laser light monitoring element 124, a coupling lens 123 to an optical fiber 126, and a thermistor 122, which is a resistance circuit element for detecting a temperature, are provided at predetermined positions of a laser mounting block 125. Mounted on Further, the bottom portion of the laser mounting block 125 and the metal hermetic package 127
The electronic cooler 128 is arranged between the bottom of the electronic cooler and the electronic cooler 128 and is tightly fixed to each other by soldering.

In the semiconductor laser device shown in FIG. 3, the required cooling performance of the electronic cooling element is determined according to the operating temperature range, and the normal operating temperature range is set to about -10.degree. C. to + 65.degree. Under this operating temperature range, the temperature of the semiconductor laser device is controlled to about 25 ° C. ± 1 ° C.

[0006] In a semiconductor laser device incorporating the semiconductor laser element formed as described above, a demand for an operating temperature range is -20 as the application field is expanded recently.
It has spread to about + 85 ° C. In order to respond to the requirement of this wide operating temperature range, as shown in FIG.
Between the block 115 on which the semiconductor laser element 111 is mounted and the bottom plate of the hermetic package 117, a plurality of (two in this case) stacked electronic cooling elements 18a, 18
b, the cooling capacity of each electronic cooling element can be superimposed, and the cooling capacity can be changed by changing the electronic cooling element to be supplied and the combination thereof in accordance with the ambient temperature. It is disclosed in JP-A-6082.

[0007]

In the conventional semiconductor laser device shown in FIG. 4 having an electronic cooling device composed of two layers of electronic cooling elements shown in FIG. 4, the one-stage electronic cooling element shown in FIG. Although the cooling capacity is improved compared to the semiconductor laser device to be cooled, the semiconductor laser device and the laser light monitoring device are mounted on the laser mounting block fixed on the cooling surface of the upper electronic cooling device. , A coupling lens to an optical fiber, and a thermistor for temperature detection. Therefore, the heat capacity of the laser light monitoring element and the coupling lens to the optical fiber is much larger than the heat capacity of the semiconductor laser element and the temperature detecting thermistor. There is a disadvantage that the temperature control of the detection thermistor becomes insufficient.

An object of the present invention is to provide a semiconductor laser module having an electronic cooling device including a two-stage electronic cooling element, in which optical components such as a lens and a photodetector having a large heat capacity are provided on the first-stage electronic cooling element. It is an object of the present invention to provide a semiconductor laser module having an improved cooling capability by mounting a semiconductor laser element and a thermistor for monitoring the temperature of the semiconductor laser element on the second stage electronic cooling element.

[0009]

According to the present invention, there is provided a semiconductor laser module comprising: a carrier on which a semiconductor laser element and a thermistor for monitoring the temperature of the semiconductor laser element are mounted; and a bottom plate of a housing accommodating the carrier. In a semiconductor laser module including an electronic cooler including an electronic cooling element formed in at least two stages, a first lens for collimating laser light emitted from the semiconductor laser element, and light for monitoring the laser light A first electronic cooling element mounted with a detector and fixed on a bottom plate of the housing;
A second electronic cooling element having a carrier on which a semiconductor laser element and a thermistor are mounted fixedly mounted on the first electronic cooling element;

[0010] The first lens and the photodetector are mounted on the first electronic cooling element via a plate-shaped carrier, and the carrier has an opening at the center for passing the second electronic cooling element. The opening and the second electronic cooling element are in a fitting relationship. Furthermore, the second lens for condensing the collimated laser light is fixed outside the housing.

As described above, the electronic cooler of the semiconductor laser module has a two-stage structure, and a first lens having a large heat capacity and a photodetector are mounted on the lower first electronic cooler. A semiconductor laser element having a relatively small heat capacity and requiring precise temperature control and a thermistor are mounted on the second thermoelectric cooling element, and a thermoelectric element forming an upper stage and a lower stage The number and arrangement of the semiconductor laser elements are set in consideration of the above-mentioned heat capacity, and the power supply suitable for the operating temperature range is performed in each of the upper and lower sections, so that the cooling characteristics of the module including the semiconductor laser elements and the Oscillation characteristics are improved. Also, by providing the second lens for focusing outside the housing,
Since the heat capacity of the optical system component requiring the temperature adjustment is reduced, the cooling characteristics of the semiconductor laser module can be improved.

[0012]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a schematic longitudinal sectional view of an embodiment of a semiconductor laser module according to the present invention, and FIG. 2 is a schematic plan view of FIG. 1 with an upper lid removed.

In FIG. 1, a semiconductor laser device 1 is a photoelectric conversion device that converts an electrical input into an optical output and emits a required laser beam for use in optical communication. The heat sink 21 is a pedestal for mounting the semiconductor laser device 1 and improving heat radiation of the semiconductor laser device. The semiconductor laser carrier 31 has a heat sink 21 and a thermistor 8 for monitoring the temperature of the semiconductor laser element 1 mounted on the upper surface, and fix them by soldering.

An electronic cooler 6 having a two-stage structure consisting of an upper stage 11 and a lower stage 12 is provided with a thermoelectric device for controlling the temperature for stabilizing the optical output and wavelength of the semiconductor laser device 1 and for controlling the temperature of the optical system. It is composed of a thermoelectric element having an exchange function. The upper substrate 11a of the upper part 11 forms a cooling substrate, on which a semiconductor laser carrier 31 is mounted and fixed by soldering. Bottom side substrate 1 of lower part 12
2a forms a heat radiation side substrate, and is fixed by soldering on the bottom plate of the module package 4 forming a metal hermetic housing on the lower surface so that heat of the heat radiation side substrate is effectively radiated by conduction. Is formed.

A common substrate 12b provided between the upper portion 11 and the lower portion 12 has an upper portion 11 on the upper surface side.
And a cooling-side wiring pattern of the lower portion 12 is formed on the lower surface side, so that the heat-radiating surface and the cooling surface are combined.

On the upper surface of the common substrate 12b, a plate-like carrier 32 for mounting optical components is fixed by soldering. An opening 51 is provided substantially at the center of the carrier 32, and the upper portion 11 penetrates through the opening 51. The shape and dimensions of the opening 51 are such that the upper portion 11 penetrating therethrough can just fit.
By forming the opening 51 in this way, the displacement of the carrier 32 can be prevented.

A first lens 2 for collimating the laser light emitted from the semiconductor laser element 1 is provided on a carrier 32 for mounting optical components provided on the upper surface of the common substrate 12b. Is fixed by the lens holder 2a. First lens holder 2a and carrier 32
And between the first lens holder 2a and the first lens 2 are fixed using YAG laser welding.

On the carrier 32, a photodetector 7 (PD) for monitoring a laser beam is fixed by YAG laser welding. The optical component having a large heat capacity is placed on the lower portion 12 having a large cooling capacity.
2 is fixed.

As described above, the upper stage 11 of the electronic cooler 6
Is mounted with only the semiconductor laser element 1 having a small heat capacity and requiring precise temperature control, its heat sink 21 and the thermistor 8, and an optical component having a large heat capacity is provided on the lower part 12 of the electronic cooler 6. , A holder 2a and a photodetector (PD) 7 of the first lens 2,
The number and arrangement of the thermoelectric elements forming the upper section 11 and the lower section 12 are set in consideration of the above-mentioned heat capacity, and the power supply suitable for the operating temperature range is supplied to the upper section 11 and the lower section 12.
By doing so, the cooling characteristics of the module including the semiconductor laser device 1 can be improved.

In the present semiconductor laser module, a second lens 3 for condensing including the optical axis of the laser beam outside the module package 4 is fixedly mounted by a second lens holder 3a, and an optical fiber 5 is further provided. It is held by the fiber holder 5a and fixed to the second lens holder 3a. The axis of the optical fiber 5 needs to be fixed so as to exactly coincide with the optical axis of the optical system formed by the first lens 2 and the second lens 3. Therefore, the optical fiber 5 and the fiber holder 5
a, the fiber holder 5a and the second lens holder 3a, and the second lens holder 3a and the module package 4 are all fixed by YAG laser welding.

Next, the operation of the semiconductor laser module will be described. The laser light emitted from the semiconductor laser element 1 is collimated by the first lens 2 and
Is condensed by the lens 3 and is coupled with the optical fiber 5,
It is taken out from the other end of the optical fiber 5 by an optical connector (not shown) or the like.

In order to stabilize the optical output and wavelength of the semiconductor laser device 1, the thermistor 8 electrically monitors the temperature of the semiconductor laser device 1 and an electronic cooler so that the resistance value of the thermistor 8 becomes a predetermined value. 6, the temperature of the semiconductor laser device 1 is controlled. The electronic cooler 6 has an upper section 11
The semiconductor laser device 1 which requires precise temperature control and has a small heat capacity is mounted on the upper stage 11, and an optical device having a large heat capacity is mounted on the lower stage 12. First lens 2 and photodetector 7 as parts
Is mounted, the cooling characteristics of the semiconductor laser device 1 are improved, and the heat radiating portion of the upper portion 11 can be cooled by the lower portion 12, so that the cooling capacity is lower than that of the one-stage cooled electronic cooler. improves. Further, by providing the second lens for condensing light out of the package 4 of the optical system components, the heat capacity of a portion requiring temperature adjustment can be reduced, so that the cooling characteristic of the semiconductor laser module is improved. be able to.

[0023]

As described above, according to the present invention, an electronic cooler used for cooling a semiconductor laser module has a two-stage structure in which a semiconductor laser element and a thermistor are mounted on an upper stage and an optical cooler having a large heat capacity is mounted on a lower stage. Because the components are mounted, the cooling capacity is improved and the cooling characteristics are improved, the laser oscillation characteristics are stabilized, and an opening is provided in the carrier on which the optical components are mounted. Since the upper portion is fitted, the carrier is prevented from being displaced. Furthermore, since the second lens for condensing is provided outside the package, the heat capacity of the portion requiring temperature adjustment is reduced, which is effective in improving the cooling performance of the semiconductor laser module.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view of a semiconductor laser module of the present invention.

FIG. 2 is a schematic plan view of FIG. 1 from which an upper lid is removed.

FIG. 3 is a schematic longitudinal sectional view of a semiconductor laser module according to the prior art.

FIG. 4 is a view similar to FIG. 3;

[Explanation of symbols]

1, 111, 121 Semiconductor laser element 2 First lens 2a First lens holder 3 Second lens 3a Second lens holder 4, 117, 127 Housing / module package /
Metal airtight package 5, 116, 126 Optical fiber 5a Optical fiber holder 6, 118, 128 Electronic cooler 7, 114, 124 Photodetector (PD) / laser light monitoring element 8, 112, 122 Thermistor 11, 18b Upper part / Second-stage electronic cooling element 11a Upper substrate 12, 18a Lower part / First-stage electronic cooling element 12a Bottom substrate 12b Common substrate 21 Heat sink 31 Semiconductor laser carrier 32 Carrier 51 Opening 113,123 Coupling lens 115,125 Laser mounting block

Claims (6)

[Claims] 1. An electronic cooling device formed in at least two stages between a carrier on which a semiconductor laser device and a thermistor for monitoring the temperature of the semiconductor laser device are mounted, and a bottom plate of a housing accommodating the carrier. A semiconductor laser module comprising an electronic cooler including: a first lens for collimating laser light emitted from the semiconductor laser element, and a photodetector for monitoring the laser light, A first electronic cooling element fixed on the bottom plate of the housing, and the carrier on which the semiconductor laser element and the thermistor mounted on the first electronic cooling element are mounted on the first electronic cooling element. A semiconductor laser module comprising: a fixed second electronic cooling element. 2. The semiconductor laser module according to claim 1, wherein the semiconductor laser device has a heat sink for improving heat radiation between the semiconductor laser device and the carrier on which the semiconductor laser device is mounted. 3. The first lens and the photodetector mounted on the first electronic cooling element are mounted via a plate-shaped carrier fixed on an upper surface of the first electronic cooling element. The semiconductor laser module according to claim 1, wherein: 4. The carrier according to claim 3, wherein the plate-shaped carrier fixed on the upper surface of the first electronic cooling element has an opening for passing the second electronic cooling element at a central portion. Semiconductor laser module. 5. The shape of the opening of the plate-like carrier is as follows:
5. The semiconductor laser module according to claim 4, wherein said semiconductor laser module has a fitting relationship with said second electronic cooling element. 6. A second lens for condensing the laser light collimated by the first lens and coupling the laser light to an optical fiber is fixed to the housing outside the housing. Item 2. A semiconductor laser module according to item 1.