JPH07302947A - Wavelength stabilizing device - Google Patents

Abstract

PURPOSE:To provide a small wavelength stabilizing device, wherein an LD is lessened in temperature change caused by a change in ambient temperature and stabilized in oscillation frequency. CONSTITUTION:A semiconductor laser 24, a semiconductor laser holding member 22 which holds the semiconductor laser 24, a temperature sensor 22 arranged adjacent to the semiconductor laser 24, and a Peltier element 26 which heats up or cools down the semiconductor laser 24 on the basis of detection signals sent from the temperature sensor 22 are provided. A groove 38 is provided to the semiconductor laser holding member 22 so as to restrain heat from being transmitted to the semiconductor laser 24 and its vicinity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wavelength stabilizing device for stabilizing the wavelength of laser light emitted from a semiconductor laser light source.

[0002]

2. Description of the Related Art Conventionally, a semiconductor laser (hereinafter simply referred to as L
It is known that the oscillation wavelength of (D) is largely changed by a slight temperature change. Therefore, conventionally, there is known a wavelength stabilizing device as shown in FIG. 3, which stabilizes the oscillation wavelength by stabilizing the temperature of the LD. Hereinafter, a conventional wavelength stabilizing device will be described.

The LD holding body 2 for holding the LD 4 provided with the Peltier element 6 is attached to the mounting portion 16 by the mounting screw 14.
It is fixed to. The temperature of the LD 4 is maintained at a predetermined temperature by supplying a driving current to the Peltier device 6. In this case, a temperature sensor 8 for detecting the temperature of the LD 4 is provided in the vicinity of the LD 4, and the temperature control unit 12 controls the driving current of the Peltier element 6 based on the temperature detection signal output from the LD temperature sensor 8. Is controlled to maintain the LD 4 at a predetermined temperature.
It should be noted that the Peltier element 6 is provided with a heat radiating fin 10 for radiating heat generated in the Peltier element.

[0004]

However, as shown in FIG. 3, the LD temperature sensor 8 has its measuring point LD4.
When the ambient temperature around the LD holder 2 changes, the mounting portion 16
The temperature changes and the heat conduction from the vicinity of the mounting screw 14 causes the following problems.

FIG. 4 is a graph showing the relationship between the thermal resistance value and the temperature with reference to the position of the LD temperature sensor 8 during temperature control. As described above, the LD temperature sensor 8
Since its installation point does not coincide with the light emitting point of the LD 4, there is some thermal resistance between them. Further, in the LD 4, when the environmental temperature changes, as described above, the thermal change is transmitted via the mounting portion 16 or the mounting screw 14, so that the position affected by the environmental temperature (environment of the graph There is also a predetermined thermal resistance between the temperature position) and the LD 4.

Now, as shown in FIG. 4, the LD temperature sensor 8
Temperature (T _A ) is stabilized at the set temperature (T _A0 ), and the temperature of LD 4 ( _TL ) and the ambient temperature (T _B ) at that time are assumed to be on the solid line in the figure. To do. Consider a case where the environment temperature (T _B ) is lower than the temperature indicated by the solid line in this state. When the temperature control is performed in this state, the LD temperature sensor 8 is held at the set temperature (T _A0 ), but the LD 4 is kept at the temperature (T
It will be stabilized at a temperature that is ΔT _L higher than _L ). That is, even if the LD temperature sensor 8 is controlled so as to be maintained at a constant temperature, the thermal resistance exists between the LD temperature sensor 8 and the LD 4, so that the LD 4 is not controlled to a predetermined temperature. There is a problem that the oscillation wavelength of the laser light emitted from the LD 4 is not stable.

In Japanese Utility Model Laid-Open No. 2-15761, the LD holder 2 is made of a material having a relatively high thermal resistance such as a polymer material so that the distance between the LD 4 and the ambient temperature shown in the graph of FIG. It is shown that ΔT _L is made as small as possible by widening.

However, it is not sufficient to stabilize the LD4 in which the wavelength greatly changes due to a slight temperature change, and the LD holder 2 is required to further increase the thermal resistance.
If is large, the entire device becomes large.

It is an object of the present invention to provide a small wavelength stabilizer which can stabilize the oscillation wavelength of the LD by reducing the temperature change (ΔT _L ) of the LD due to the change of the ambient temperature. .

[0010]

In order to solve the above-mentioned problems, a wavelength stabilizing device of the present invention includes a semiconductor laser, a semiconductor laser holding member for holding the semiconductor laser, and a semiconductor laser holding member arranged near the semiconductor laser. A temperature sensor and heating and cooling means for heating or cooling the semiconductor laser based on a detection signal from the temperature sensor. The semiconductor laser holding member transfers heat to the periphery of the held semiconductor laser. It is characterized in that a groove for cutting off is formed.

Further, the wavelength stabilizing device of the present invention includes an etalon on which light from a semiconductor laser is incident, an etalon holding member for holding the etalon, a temperature sensor arranged near the etalon, and a temperature sensor for the temperature. A heating / cooling unit for heating or cooling the temperature of the etalon based on a detection signal from the sensor, and a photodetector for detecting light transmitted through a specific mode of the etalon, are held by the etalon holding member. A groove that blocks heat transfer is formed around the etalon.

[0012]

According to the wavelength stabilizing device of the first aspect, the temperature sensor is arranged near the semiconductor laser held by the semiconductor laser holding member and provided with the Peltier element. A control current is supplied to the Peltier element so that the temperature detected by the Peltier element becomes the set temperature. As a result, the semiconductor laser is controlled to reach the set temperature. A groove is formed around the semiconductor laser in the semiconductor laser holding member, so that a change in ambient temperature is less likely to be transmitted to the semiconductor laser. Further, as described in claim 2, by fixing the heat radiation fin fixed to the Peltier element to the semiconductor laser holding member via the spacer, it is difficult to transfer the heat from the heat radiation fin to the semiconductor laser. ing.

According to the wavelength stabilizing device described in claim 3, the emitted light is monitored by using the etalon so as to further stabilize the wavelength of the light emitted from the semiconductor laser. Has been done. In this case, also in the etalon holding member, similarly, a groove is formed around the etalon, and it is difficult for the change in environmental temperature to be transmitted to the etalon. Further, as described in claim 4, by fixing the heat radiation fin fixed to the Peltier element provided in the etalon to the etalon holding member via the spacer, the heat from the heat radiation fin is transmitted to the etalon. Making it difficult to convey. In this case, as described in claim 5, a photodetector for detecting the light transmitted through the etalon is provided in the fin for heat dissipation, and the overall size of the device is reduced.

[0014]

The preferred embodiments of the wavelength stabilizing device according to the present invention will be described below. As shown in FIG. 1 (a), the wavelength stabilizer of the present embodiment has a mounting portion 36 with a mounting screw 34.
It has an LD holder 22 fixed to. In the LD holder 22, a Peltier element 26 is fixed, and an LD 24 that emits laser light of a predetermined wavelength is held.
A temperature sensor 28 that detects the temperature of the LD 24 is provided near the LD 24, and the temperature control unit 32 is based on the temperature detection signal output from the LD temperature sensor 28.
Controls the drive current of the Peltier element 26 to maintain the LD 24 at the set temperature. The Peltier element 26 is a heating / cooling element, and when one side is a heating side, the other side is a cooling surface. As described above, since a certain amount of heat is accumulated in the Peltier element 26, the fins 30 for heat dissipation are attached.

The LD holder 22 is made of a material having a low thermal conductivity,
For example, it is made of a polymer material and has a lower thermal conductivity than the LD 24. A groove 38 is formed around the LD 24 in the LD holding body 22, so that the mounting portion 36, the mounting screw 34, and the mounting screw 34 can prevent a temperature change due to a change in environmental temperature or the like.
It is configured not to be transmitted to the LD 24 via the. That is, by forming the groove 38, an air layer having a lower thermal conductivity is formed, and the influence of temperature change is less likely to be transmitted to the LD 24.

The heat dissipating fins 30 are also susceptible to environmental temperature due to their construction. Normally, the fins 30 for heat dissipation are in a state of being thermally connected to the LD holding body 22, so the LD 24 is easily affected by the heat from the fins 30 for heat dissipation. For this reason, in the present embodiment, the fins 30 for heat dissipation are further fixed to the LD holding body 22 by the spacers 39 which are arranged at a predetermined interval and have a low thermal conductivity, for example, a polymer material. is doing. In this way, since the fins 30 for heat dissipation are fixed through the spacer 39 having a low thermal conductivity, the influence of temperature change is less likely to be transmitted to the LD 24.

FIG. 1B is a view of FIG. 1A viewed from the optical axis direction and shows the structure of the groove 38 and the spacer 39. As is apparent from the figure, the grooves 38 are formed at predetermined intervals on the circumference so as to surround the LD 24. Further, the fins 30 for heat dissipation are formed by four spacers 3 which are spaced apart from each other outside the position where the groove 38 is not formed.
It is connected to the LD holding body 22 via 9. Of course, the configuration of the groove 38 and the spacer 39 is an example, and can be variously modified. For example, if the grooves 38 are formed in a circumferential shape without a predetermined interval, the thermal resistance can be further increased. In addition, in this case, L of the spacer 39
If the mounting position to the D holding body 22 is configured outside the groove 38, the LD 24 is further less susceptible to the influence of heat change. Of course, the position, number, etc. of the spacers 39 can be modified appropriately.

As described above, since the thermal resistance up to the LD 24 is increased, the distance (thermal resistance) between the LD 4 and the environmental temperature shown in FIG. 4 is greatly increased, and the environmental temperature changes as shown by the dotted line. Even in this case, the temperature change (ΔT _L ) of the LD 24 can be reduced and the oscillation wavelength of the LD 24 can be stabilized. In addition, in this way, the LD holder 2
Since it suffices to form the groove 38 in 2 and provide a spacer, the oscillation wavelength can be stabilized with a simple configuration without increasing the size of the entire device.

FIG. 2 is a diagram showing a state in which a device for controlling the oscillation wavelength is incorporated in the device for stabilizing the wavelength of the LD 24 shown in FIG. The laser light emitted from the LD 24 is split by a branching prism 70 arranged in the middle of the optical path, one of which is directed to a unit using the laser light and the other of which is directed so as to enter an etalon 44 of the wavelength control device. To be

The etalon 44 has a periodic transmission spectrum characteristic. Therefore, by arranging the photodetector 60, monitoring the light transmitted through the target mode, and controlling the injection current to the LD 24 via the wavelength control means 80,
By controlling the wavelength of 24, it becomes possible to emit laser light of a stable wavelength.

In this case, the etalon 44 changes its refractive index and thermally expands due to the change of the ambient temperature, and the periodic spectral characteristics change. Therefore, the etalon 44 cannot be accurately monitored unless the temperature of the etalon is stabilized, and the LD 24 is The oscillation wavelength is not stable. Therefore, the etalon 44 is also configured so as not to be affected by the change in the environmental temperature. The configuration will be described below.

As shown in FIG. 2, the etalon 44 is provided in the Peltier element 46 to which the fins 50 for heat dissipation are attached, and in the etalon holder 42 fixed to the attachment portion 56 by the attachment screw 54. Is held. An etalon temperature sensor 48 that detects the temperature of the etalon 44 is provided near the etalon 44. The temperature detection signal output from the etalon temperature sensor 48 is input to the temperature control unit 52, and the temperature control unit 52 controls the drive current to the Peltier element 46 based on the detection signal to control the temperature of the etalon 44 to a predetermined value. Keep at temperature.

The etalon holder 42 is made of a material having a low thermal conductivity, for example, a polymer material. A groove 58 is formed around the etalon 44 in the etalon holder 42, and is configured so as not to transmit a temperature change due to a change in environmental temperature or the like to the etalon 44 via the mounting portion 56 and the mounting screw 54. There is. That is, by forming the groove 58, an air layer having a lower thermal conductivity is formed,
The influence of temperature change is less likely to be transmitted to the etalon 44.

Similarly to the structure shown in FIG. 1, the radiating fins 50 are also etaloned by spacers 59 made of a material having a low thermal conductivity, such as a polymer material, which are arranged at predetermined intervals. It is fixed to the holder 42. Since the fins 50 for heat dissipation are fixed via the spacers 59 having a low thermal conductivity in this manner, the influence of temperature change is less likely to be transmitted to the etalon 44. In the configuration example shown in the drawing, the grooves 58 are formed at predetermined intervals on the circumference so as to surround the etalon 44, and the spacers 59 are not formed with the grooves on the circumference. It is fixed to the part. Further, the photodetector 60 described above is preferably fixed in the fin 50 for heat dissipation, as shown in the figure, so that the entire apparatus can be downsized.

As described above, as in the configuration shown in FIG. 1, the temperature change of the etalon 44 due to the change of the ambient temperature can be reduced, so that the spectral characteristics of the etalon 44 are stabilized and the injection into the LD 24 is performed. The current can be controlled. That is, the oscillation wavelength of the LD 24 can be further stabilized. Further, similarly to the above, since it is sufficient to form the groove 58 by forming the etalon holder 42 with a material having a low thermal conductivity, it is possible to stabilize the oscillation wavelength of the LD 24 with a simple structure without increasing the size of the entire device. be able to.

Although the preferred embodiments of the wavelength stabilizing device according to the present invention have been described above, the present invention is not limited to the above-described embodiments, but can be variously modified. For example,
Although the etalon 44 shown in FIG. 2 is a solid type, it may be configured by an air gap type, for example. In addition, the grooves 38, 5 shown in FIGS.
For example, if 8 is filled with a foam filler having a heat insulating effect,
Thermal isolation between the LD 24 and the etalon 44 and the outside can be sufficiently performed, and the oscillation wavelength of the LD 24 can be stabilized.

[0027]

As described above, according to the wavelength stabilizing device of the present invention, the laser light emitted from the LD can be emitted even if the ambient temperature changes, with a simple structure without increasing the size of the device. It is possible to stabilize the oscillation wavelength.

[Brief description of drawings]

FIG. 1A is a view showing an embodiment of a wavelength stabilizing device of the present invention, and FIG. 1B is a view of an LD holder in this embodiment seen from the optical axis direction.

FIG. 2 is a diagram showing a state in which a device for controlling the wavelength is incorporated in the device for stabilizing the oscillation wavelength of the LD shown in FIG.

FIG. 3 is a diagram showing a configuration of a conventional wavelength stabilizing device.

FIG. 4 is a graph showing a relationship between a thermal resistance value and temperature with reference to the position of an LD temperature sensor during temperature control.

[Explanation of symbols]

22 ... Semiconductor laser holding member, 24 ... Semiconductor laser, 2
6, 46 ... Peltier element, 28, 48 ... Temperature sensor, 3
0, 50 ... Fins for heat dissipation, 39, 59 ... Spacers, 4
2 ... Etalon holding member, 44 ... Etalon.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yukio Eda 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside Olympus Optical Co., Ltd.

Claims (5)

[Claims] 1. A semiconductor laser, a semiconductor laser holding member for holding the semiconductor laser, a temperature sensor arranged in the vicinity of the semiconductor laser, and heating or heating the semiconductor laser based on a detection signal from the temperature sensor. A heating and cooling means for cooling the semiconductor laser holding member, wherein the semiconductor laser holding member is provided with a groove for cutting off heat transfer around the held semiconductor laser. 2. The wavelength stabilizer according to claim 1, further comprising a fin for radiating heat in said heating / cooling means and for radiating heat attached to said semiconductor laser holding member via a spacer. apparatus. 3. An etalon on which light from a semiconductor laser is incident, and an etalon holding member which holds this etalon,
A temperature sensor arranged in the vicinity of the etalon, heating and cooling means for heating or cooling the temperature of the etalon based on a detection signal from the temperature sensor, and a photodetector for detecting light transmitted through the etalon, The wavelength stabilizing device is characterized in that the etalon holding member is provided with a groove for blocking heat transfer around the held etalon. 4. The wavelength stabilizing device according to claim 3, further comprising a fin for radiating heat in the heating / cooling means, the fin being attached to the etalon holding member via a spacer. . 5. The wavelength stabilizing device according to claim 4, wherein a photodetector for detecting light transmitted through the etalon is provided inside the fin for heat dissipation.