JP2003008137A - Semiconductor laser device, optical fiber amplifier using the same, and method of controlling and driving semiconductor laser device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor laser device which is simple in structure, small in size, and capable of oscillating stably a laser beam having a certain wavelength independently of an increase or a reduction in a drive current. SOLUTION: A semiconductor laser device 1 is equipped with a Peltier cooler 9 which cools down or heats a semiconductor laser element 2, a current detector 11 which detects a change in a drive current Iop applied to the semiconductor laser element 2, and a temperature control unit 12 which controls the Peltier cooler 9 so as to enable a relation between the measured temperature of a temperature measuring element 5 and the detected drive current of the current detector 11, to satisfy the relation between the drive current Iop which makes the wavelength of a laser beam oscillated by the semiconductor laser element 2 nearly constant and the measured the temperature Ts of the temperature measuring element 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser device suitable for a Raman amplifier pumping light source, an EDFA pumping light source, or other optical fiber amplifier pumping light source and capable of outputting a laser beam having a stable wavelength. The present invention relates to an optical fiber amplifier used and a drive control method for a semiconductor laser device.

[0002]

2. Description of the Related Art Conventionally, a semiconductor laser device which outputs a laser beam as a signal beam by using a distributed feedback (DFB) laser element having a built-in diffraction grating has a high wavelength accuracy because it is a signal beam. Required, eg ± 0.1
High precision of nm or less is required. Therefore, a so-called wavelength lock device that controls the wavelength monitors the wavelength of the output laser light, performs feedback control so that the monitored wavelength becomes a desired wavelength, and controls the laser light having a stable wavelength. I was making it output.

[0003]

However, since the wavelength lock device monitors the wavelength of the output laser light, it requires a large, complicated and expensive optical system and a control unit, which makes the semiconductor laser device compact and lightweight. There is a problem in that the cost is hindered and the cost is increased.

The drive current applied to the semiconductor laser device that outputs laser light as signal light is, for example, 8
Although it is a small value of about 0 mA, in a DFB laser device having a built-in diffraction grating used as a pumping light source for a Raman amplifier, the driving current changes by about 1000 mA, and
A high power laser beam of 00 mW or more is emitted. For this reason,
The temperature of the active layer rises as the drive current increases, and the oscillation wavelength tends to shift to the long wavelength side.The semiconductor laser device used as the pumping light source of the Raman amplifier has ±
It is necessary to perform wavelength control with an accuracy of about 0.5 nm.

Generally, in a Raman amplifier pumping light source, the above-mentioned flat amplification characteristic is obtained by controlling the oscillation wavelengths of a plurality of semiconductor laser devices at predetermined wavelength intervals. Since the amplification factor changes depending on whether it is small or large, the optical output of the Raman amplifier pumping light source is increased or decreased according to the magnitude of the optical input. That is, the drive current of the Raman amplifier pumping light source is increased or decreased. As a result, as described above, the temperature of the active layer changes, the oscillation wavelength shifts, and eventually, a flat amplification characteristic cannot be obtained.

The present invention has been made in view of the above,
A semiconductor laser device capable of obtaining a stable oscillation wavelength with a simple configuration, at a small size and at a low cost, without requiring a wavelength monitor despite a large increase or decrease in drive current, an optical fiber amplifier and a semiconductor laser using the same It is an object to provide a drive control method for an apparatus.

[0007]

In order to achieve the above object, a semiconductor laser device according to a first aspect of the present invention is a semiconductor laser device based on a temperature detected by a temperature measuring device provided in the vicinity of the semiconductor laser device. In the semiconductor laser device that controls the temperature of the semiconductor laser device to control the wavelength of the laser light oscillated by the semiconductor laser device, a temperature adjusting unit that cools and heats the semiconductor laser device, and a driving current applied to the semiconductor laser device. Current detecting means for detecting a change, the current detecting means based on the relationship between the drive current at which the wavelength of the laser light oscillated by the semiconductor laser element is substantially constant and the detected temperature detected by the temperature measuring element. Temperature control means for controlling the temperature adjusting means so that the temperature detected by the temperature measuring element with respect to the value of the drive current detected by the above satisfies the relationship. Characterized by comprising.

According to the first aspect of the present invention, the temperature control means has a relationship between the drive current at which the wavelength of the laser light oscillated by the semiconductor laser element is substantially constant and the detected temperature detected by the temperature measuring element. Is held, the temperature adjusting means is controlled so that the detected temperature of the temperature measuring element with respect to the value of the drive current detected by the current detecting means satisfies the above relationship, whereby the increase or decrease of the drive current, The wavelength of the laser light is kept constant.

Further, in the semiconductor laser device according to a second aspect of the present invention, in the above invention, the temperature control means lowers the temperature detected by the temperature measuring element as the drive current detected by the current detection means increases. And controlling the temperature adjusting means to maintain the relationship.

Further, a semiconductor laser device according to a third aspect of the present invention is characterized in that, in the above invention, the semiconductor laser element forms a Fabry-Perot type resonator and oscillates a plurality of longitudinal modes.

A semiconductor laser device according to a fourth aspect is characterized in that, in the above invention, the semiconductor laser element has a built-in diffraction grating and oscillates a plurality of longitudinal modes.

Further, a semiconductor laser device according to a fifth aspect is characterized in that, in the above invention, the diffraction grating has a diffraction grating length of 300 μm or less.

In the semiconductor laser device according to a sixth aspect of the present invention, in the above invention, the diffraction grating length of the diffraction grating is provided on the first reflection film provided on the emission end face of the laser light and the reflection end face of the laser light. The length of the resonator formed by the active layer formed between the second reflection film and the (300
/ 1300) times or less.

According to a seventh aspect of the present invention, in the semiconductor laser device according to the above invention, the diffraction grating provided on the side of the first reflection film provided on the emission end face of the laser beam or in the vicinity of the first reflection film is the diffraction grating. The multiplication value of the coupling coefficient of the grating and the diffraction grating length is 0.3 or less.

According to an eighth aspect of the present invention, in the above-mentioned invention, the semiconductor laser device is characterized in that the diffraction grating changes the grating period randomly or at a predetermined period.

A semiconductor laser device according to a ninth aspect is the semiconductor laser device according to the above invention, wherein the first reflecting film is provided on the emitting end face of the laser beam and the second reflecting film is provided on the reflecting end face of the laser beam.
The resonator formed by the active layer formed between the reflective film and the reflective film has a length of 800 μm or more.

According to a tenth aspect of the present invention, in the semiconductor laser device according to the tenth aspect of the invention, the relationship is that the drive current at which the temperature of the active layer of the semiconductor laser element is substantially constant and the detected temperature detected by the temperature measuring element. It is characterized by the relationship with.

A semiconductor laser device according to an eleventh aspect of the present invention is characterized in that, in the above-mentioned invention, the temperature control means includes a storage means for holding the relationship.

According to the eleventh aspect of the present invention, the storage means of the temperature control means holds the relationship, and based on this relationship, the temperature at which the dependence of the oscillation wavelength on the driving current for each semiconductor laser device is eliminated. I'm trying to control.

According to a twelfth aspect of the present invention, in the above-mentioned invention, the semiconductor laser device comprises a setting means for inputting and setting a desired wavelength and a storage means for holding a plurality of the relationships, and the temperature control means comprises: The one relationship currently used is shifted to another relationship corresponding to the desired wavelength input and set by the setting means, and the temperature adjusting means is controlled based on the shifted relationship to obtain the desired relationship. It is characterized by controlling to the wavelength of.

According to the twelfth aspect of the present invention, the temperature control means shifts from the one relationship currently used to another relationship corresponding to the desired wavelength input and set by the setting means, Based on the shifted relationship, the temperature adjusting means is controlled to control the desired wavelength.

According to a thirteenth aspect of the present invention, in the semiconductor laser device according to the thirteenth aspect of the present invention, the relation is a control function common to a plurality of semiconductor laser device groups having the same structure and operation, and one or more drive currents. Is determined as a control function peculiar to the semiconductor laser device.

According to the thirteenth aspect of the present invention, the relation is set as a control function common to a plurality of semiconductor laser device groups having the same type of structure and operation, and the semiconductor temperature is set by setting the detected temperature for one or more drive currents. It is determined as a control function specific to the laser device.

According to a fourteenth aspect of the present invention, in the above invention, the control function is such that the detected temperature is a linear function of the drive current.

According to the fourteenth aspect of the present invention, the control function is adapted to perform a simple temperature control by using the detected temperature as a linear function of the drive current.

According to a fifteenth aspect of the present invention, in the semiconductor laser device according to the above invention, the control function is such that the detected temperature is a quadratic function of the drive current.

According to the fifteenth aspect of the present invention, the control function is a quadratic function of the drive current in which the detected temperature corresponds to the power consumption in the active layer.

An optical fiber amplifier according to a sixteenth aspect of the present invention is an optical fiber amplifier comprising the semiconductor laser device according to any one of the first to fifteenth aspects, an optical fiber for transmitting signal light, and the optical fiber. An amplification optical fiber connected to the excitation light source, a coupler for causing the excitation light emitted from the excitation light source to enter the amplification optical fiber, and an excitation light transmission optical fiber connecting the excitation light source and the coupler. It is characterized by having.

According to a seventeenth aspect of the present invention, in the above-mentioned invention, the amplification optical fiber is
It is characterized in that light is amplified by Raman amplification.

According to the eighteenth aspect of the present invention, in the above invention, the Raman amplification is performed by at least a forward pumping method.

According to a nineteenth aspect of the present invention, in the drive control method for a semiconductor laser device, the temperature of the semiconductor laser device is controlled based on the temperature detected by a temperature measuring device provided near the semiconductor laser device. In a drive control method for a semiconductor laser device that controls the wavelength of laser light oscillated by a semiconductor laser element, the detection detected by the drive current and the temperature measurement element at which the wavelength of the laser light oscillated by the semiconductor laser element is substantially constant. A relationship acquisition step of obtaining a relationship with temperature, a current detection step of detecting a change in drive current applied to the semiconductor laser element, and a detected temperature of the temperature measurement element with respect to a value of the drive current detected by the current detection step. A temperature control step of controlling the temperature of the semiconductor laser device so as to satisfy the above relation.

According to the nineteenth aspect of the present invention, first, in the relation obtaining step, the drive current at which the wavelength of the laser light oscillated by the semiconductor laser element becomes substantially constant, and the detected temperature detected by the temperature measuring element. , The current detection step, by detecting the change of the drive current applied to the semiconductor laser element, the temperature control step, the temperature detected by the temperature measuring element for the value of the drive current detected by the current detection step The process of controlling the temperature of the semiconductor laser device is repeated so as to satisfy the above relationship.

According to a twentieth aspect of the present invention, in the drive control method of the semiconductor laser device, in the above invention, the relation is that the drive current at which the active layer temperature of the semiconductor laser element is constant and the temperature measuring element detect. And the detected temperature.

According to the twentieth aspect of the invention, the relationship is obtained as a relationship between the drive current at which the temperature of the active layer of the semiconductor laser device is constant and the detected temperature detected by the temperature measuring device.

According to a twenty-first aspect of the drive control method for a semiconductor laser device, the temperature control of the semiconductor laser device is performed based on the temperature detected by a temperature measuring device provided in the vicinity of the semiconductor laser device. In a drive control method for a semiconductor laser device that controls the wavelength of laser light oscillated by a semiconductor laser element, the detection detected by the drive current and the temperature measurement element at which the wavelength of the laser light oscillated by the semiconductor laser element is substantially constant. A relationship acquisition step of obtaining a plurality of relationships with temperature, a setting input step of setting and inputting a desired wavelength,
A relationship shift step of shifting from one of the relationships currently used to another relationship corresponding to the desired wavelength input and set by the setting and input step, and a change in the drive current applied to the semiconductor laser device is detected. Current detection step, the relationship shifted by the relationship shift step and the detected temperature with respect to the value of the drive current detected by the current detection step, the temperature of the semiconductor element so as to satisfy the relationship shifted by the relationship shift step. And a temperature control step of controlling.

According to the twenty-first aspect of the present invention, the relationship between the drive current at which the wavelength of the laser light oscillated by the semiconductor laser element becomes substantially constant and the detected temperature detected by the temperature measuring element in the relationship obtaining step. , A desired wavelength is set and input by the setting input step, and the other wavelength corresponding to the desired wavelength input and set by the setting input step is selected from the one relationship currently used by the relationship shift step. Shift to the relationship, by the current detection process,
The change in the drive current applied to the semiconductor laser device is detected, and the temperature controlled step causes the relationship shifted by the relationship shift step and the detected temperature with respect to the value of the drive current detected by the current detection step to be determined by the relationship shift step. The temperature of the semiconductor element is controlled so as to satisfy the shifted relationship.

[0037]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a semiconductor laser device, an optical fiber amplifier using the same, and a drive control method for a semiconductor laser device according to the present invention will be described below with reference to the accompanying drawings.

(First Embodiment) FIG. 1 is a diagram showing a structure of a semiconductor laser device according to a first embodiment of the present invention. In FIG. 1, the semiconductor laser device 1 has a semiconductor laser element 2 arranged on a submount 4 via a metal thin film 4a. This semiconductor laser device 2 is provided with a drive current Iop by applying it to the semiconductor laser device 2.
A laser beam having a desired wavelength is oscillated and output from the active layer 3.
In this semiconductor laser element 2, a diffraction grating 3a is provided in the vicinity of the active layer 3 and desired wavelength selection is performed. Further, the drive current Iop is supplied by the variable power supply 10 and detected by the current detector 11. The drive current Iop detected by the current detector 11 is output to the temperature controller 12.

On the other hand, the temperature measuring element 5 is realized by a thermistor or the like, and is arranged on the submount 6 in the vicinity of the semiconductor laser element 2 via the metal thin film 6a. The temperature measuring element 5 is connected to the temperature control unit 12, and the temperature control unit 12 acquires the temperature Ts detected by the temperature measuring element 5.

The submounts 4 and 6 are made of a material having good thermal conductivity and insulating properties, and are arranged on the heat sink 7. The heat sink 7 is further arranged on the base 8, and a Peltier cooler 9 as a temperature adjusting means is installed below the base 8.

The temperature control unit 12 has a storage unit 13 for holding a control function which will be described later, and the drive current Iop detected by the current detector 11 is input to this control function, and the output temperature is the temperature measurement value. The Peltier cooler 9 is controlled so as to reach the temperature of the element 5. That is, the temperature control unit 12 controls the energization direction and the energization amount to the Peltier cooler 9, performs the cooling operation and the heating operation by the Peltier cooler 9, and the detected temperature of the temperature measuring element 5 corresponds to the control function. The temperature is controlled so that

Now, the control function described above will be described. FIG. 2 is a diagram showing an example of the control functions FS1 to FS3 stored in the storage unit 13 of the temperature control unit 12. In FIG. 2, a straight line L1 indicates that the driving current Iop increases or decreases.
The case where the temperature Ts detected by the temperature measuring element 5 is controlled to a constant temperature, for example, 25 ° C. is shown. In contrast,
In this embodiment, the control functions FS1 to F which are the relationships of the temperature Ts of the temperature measuring element 5 in which the temperature Tj of the active layer 3 is always constant (see the straight line L2) as the drive current Iop increases and decreases.
S3, for example, the control function FS2 is obtained, and the Peltier cooler 9 is controlled so that the temperature when the value of the drive current Iop is input to the control function FS2 becomes the temperature Ts of the temperature measuring element 5.

The temperature control unit 12 uses, for example, the control function FS.
The current direction and the amount of the current Ic with respect to the Peltier cooler 9 are changed so that the relationship of 2 is maintained, whereby temperature control is performed to keep the temperature Tj of the active layer 3 constant.
When the control functions FS1 and FS3 are set, temperature control is performed so as to maintain the relationship between the control functions FS1 and FS3.

The control functions FS1 to FS3 are driven by the drive current Iop.
Is defined by the driving range Ia. First, the control function FS2 determines the temperature Ts1 (= when the driving current Iop is 900 mA).
25 ° C.) wavelength λ2 (= 1499 nm) is measured, and then the temperature Ts2 (= 48 ° C.) that oscillates the wavelength λ2 when the drive current Iop is 100 mA, and the temperature Ts1 when the drive current Iop is 900 mA. Coordinates CP2 'and coordinates CP2' of the temperature Ts2 when the drive current Iop is 100 mA.
It is a straight line connecting to.

Similarly, the control function FS1 has a wavelength λ1 at the temperature (25 ° C.) when the drive current Iop is 1200 mA.
(= 1500.1 nm), and then the drive current I
When op is 100mA, the temperature (56
℃) is measured, and the driving current Iop is 1200 mA, the temperature (25 ° C.) coordinate CP1 and the driving current Iop are 100 m.
It is obtained as a straight line connecting the coordinate CP1 ′ of the temperature (56 ° C.) at A. Further, the control function FS3 is the wavelength λ3 of the temperature (25 ° C.) when the drive current Iop is 300 mA.
(= 1497.7 nm), and then the drive current I
When op is 900 mA, the temperature (7
℃) is measured, when the driving current Iop is 300 mA, the coordinate CP3 of the temperature (25 ° C.) and the driving current Iop are 900 mA.
It is obtained as a straight line connecting the coordinate CP3 ′ of the temperature (7 ° C.) at the time.

These control functions FS1 to FS3 do not have a characteristic that the temperature Tj of the active layer 3 is constant, but since the temperature Tj of the active layer 3 itself cannot be measured, the control functions FS1 to FS3 are almost equivalent to the temperature of the active layer 3 itself. The wavelength of the laser light that appears is measured, and this wavelength is required to be constant.

Any one of the control functions FS1 to FS3 is stored in the storage unit 13, and the temperature control unit 12 uses the drive current Iop detected by the current detector 11 and the detected temperature Ts detected by the temperature measuring element 5 as a basis. Then, the Peltier cooler 9 is drive-controlled so that the detected temperature Ts satisfies the control function stored in the storage unit 13, for example, the control function FS2.

By performing the temperature control by the control function FS2, the oscillation wavelength becomes constant at the wavelength λ2, so that the oscillation wavelength jump due to the shift of the oscillation wavelength is eliminated, and the kink on the current-output characteristic is reduced. Also, the dynamic stability of the oscillation wavelength can be obtained. In addition, the control function FS
By performing temperature control based on 1 and FS3, it is possible to control wavelengths to constant oscillation wavelengths λ1 and λ3, respectively.

FIG. 3 is a diagram showing a wavelength control result based on the control functions FS1 to FS3. In FIG. 3, the characteristic L
3 shows a change in the oscillation wavelength λ when the temperature control is performed based on the straight line L1, and the drive current Iop is 10
The oscillation wavelength λ shifts to the long wavelength side as it increases from 0 mA to 1200 mA, and shifts by about 2 nm. On the other hand, when the temperature control is performed based on the control functions FS1 to FS3, the drive current Iop is 100 mA to 1200.
Even when the current is increased to mA, the oscillation wavelengths λ1 to λ3 are constant.
Is maintained. For example, the wavelength when temperature control is performed based on the control function FS2 is λ2 ± 0.5n
It is possible to maintain the accuracy of m and output a laser beam having a stable wavelength. The black square marks and the black diamond marks shown in FIGS. 2 and 3 are actually measured values.

In this case, since the wavelength monitor is not performed, an optical system is not required, an inexpensive semiconductor laser device can be realized, and the structure of the semiconductor laser device can be simplified and downsized.

By the way, the control function FS1 shown in FIG.
Was a linear function, but it may be a control function FS11 of a quadratic function as shown in FIG. Generally, the drive current I
The temperature rise of the active layer 3 due to the increase of op is divided into power consumed for laser oscillation and power consumed by the resistance of the active layer 3, and the power consumed by the resistance of the active layer 3 is
Since this resistance is a value obtained by multiplying the square of the drive current Iop, the temperature change of the active layer 3 with respect to the drive current Iop is
It is thought to change squared. That is, the built-in voltage of the active layer 3 is "V0", the series resistance of the laser element of the active layer 3 is "R", and the drive current Iop of the drive voltage V is set.
Is applied to the semiconductor laser device, the total power W becomes: W = Iop.V = (V0 + R.Iop) .Iop = V0R + Iop2R Since 80 to 90% of this total electric power W is converted into Joule heat, the temperature change of the active layer 3 becomes a quadratic function of the drive current Iop. Therefore, by setting the control function FS2 of a quadratic function, the oscillation wavelength can be further stabilized.

Further, as shown in FIG. 5, the control function may be an arbitrary control function FS (Iop). In general, since the characteristics of the laser oscillation efficiency of the control function largely change depending on the structure and operation of the semiconductor laser device 1, the control function FS (Iop) corresponding to the type of each semiconductor laser device.
May be defined and used. In this case, the control function FS (Iop) of each semiconductor laser device 1 is further added.
Is measured at a point P1 between the drive current Iα in each semiconductor laser device 1 and the detected temperature Tα of the temperature measuring element 5 at this time, and the control function FS (Iop) is finally determined based on the measured result. You may do it. Further, the control function FS (Iop) may be determined by adding not only one point but also another point P2 and performing an approximation process. in this case,
A more accurate control function can be obtained.

The control function F shown in FIGS. 2 and 3 is used.
In the temperature control based on S2, the value for correcting the wavelength shift shown in FIG. 3 is used as a new control function added to the control function FS2, so that the wavelength control of each semiconductor laser device can be performed more accurately. You can

A drive control method for the semiconductor laser device according to the embodiment of the present invention will now be described with reference to the flowchart shown in FIG. In FIG. 6, first,
A driving current Iα is applied to the semiconductor laser device 1 within the driving range Ia, a detection temperature Tα (point P1) of the temperature measuring element 5 detected at this time is acquired, and another driving current Iβ is further added. The detected temperature Tβ (point P2) of the temperature measuring element 5 detected at 1 is acquired, and the straight line connecting these two points P1 and P2 is determined as the control function (step S10).
1). When acquiring these points P1 and P2, the Peltier cooler 9 is controlled so that the oscillation wavelengths are the same. Then, the determined control function is stored in the storage unit 13 (step S102). These steps S101 and S102
The process of is performed in advance.

After that, when the semiconductor laser device 1 is actually driven, the temperature control section detects the drive current Iop detected by the current detector 11 (step S103), and the detected drive current Iop is stored in the storage section 13. Then, the Peltier cooler 9 is controlled so that the current value at this time becomes the detected temperature Ts of the temperature measuring element 5 (step S104). Then, after step S103, the drive current Iop is further detected, and step S10
3, the process of S104 is repeated. As a result, even if the drive current Iop changes, the oscillation wavelength does not shift.

Particularly, when a plurality of semiconductor laser devices 1 are used as the Raman amplifier pumping light source, the oscillation wavelength does not change despite the increase or decrease of the drive current Iop. The dependency remains flat and good amplification characteristics can be maintained.

By the way, in the semiconductor laser device 2 shown in FIG. 1, a plurality of longitudinal mode oscillations are generated by giving fluctuations in wavelength selection to the diffraction grating 3a, etc. It is supposed to be used as a light source (see Japanese Patent Application No. 2000-323118).

Here, the detailed structure of the semiconductor laser device 2 will be described. FIG. 7 shows a schematic perspective view of the semiconductor laser device 2 shown in FIG. 1, and FIG. 8 shows a side sectional view of the semiconductor laser device 2 shown in FIG. In FIG. 8 and FIG. 9, the semiconductor laser devices are arranged on the n-InP substrate 1 in order of n.
-InP buffer layer 22, GRIN-SCH-MQW
(Graded Index-Separate Confinement Hetero structu
re Multi Quantum Well: A distributed refractive index separation confined multiple quantum well) active layer 3 and a p-InP spacer layer 24 are laminated. Here, the upper region of the n-InP buffer layer 22, the GRIN-SCH-MQW active layer 3 and p-.
The InP spacer layer 24 has a mesa stripe structure having a longitudinal direction in the light emission direction, and a p-InP blocking layer 28 and an n-InP blocking layer 29 are sequentially stacked adjacent to this structure. A p layer is formed on the p-InP spacer layer 24 and the n-InP blocking layer 29.
A -InP clad layer 26 and a p-GaInAsP contact layer 27 are laminated. In addition, p-GaInAsP
A p-side electrode 30 is arranged on the contact layer 27, and n−
An n-side electrode 31 is arranged on the back surface of the InP substrate 21. Further, as shown in FIG. 8, the emission side reflection film 35 is arranged on the laser light emission end face, and the reflection side reflection film 34 is arranged on the reflection end face opposite to the laser light emission end face. The diffraction grating 3a is arranged in the p-InP spacer layer 24.

The n-InP buffer layer 22 has a function as a cladding layer in addition to a function as a buffer layer. Specifically, the n-InP buffer layer 22 is a GRI.
The GRIN-SCH-MQW active layer 3 has a refractive index lower than the effective refractive index of the N-SCH-MQW active layer 3.
It has a function of vertically confining light generated from the.

The GRIN-SCH-MQW active layer 3 has a distributed index separation confinement multiple quantum well structure and has a function of effectively confining carriers injected from the p-side electrode 30 and the n-side electrode 31. GRIN-SCH-M
The QW active layer 3 has a plurality of quantum well layers and exhibits a quantum confinement effect in each quantum well layer. Due to this quantum confinement effect, the semiconductor laser device 2 has high luminous efficiency.

The p-GaInAsP contact layer 27 is composed of
This is for ohmic contact between the p-InP cladding layer 26 and the p-side electrode 30. p-GaInAs
The P contact layer 27 is heavily doped with p-type impurities, and has a high impurity density to achieve ohmic contact with the p-side electrode 30.

P-InP blocking layer 28 and n-
The InP blocking layer 29 is for internally confining the injected current. In this semiconductor laser device 2, since the p-side electrode 30 functions as an anode, a reverse bias is applied between the n-InP blocking layer 29 and the p-InP blocking layer 28 when a voltage is applied. It Therefore, the n-InP blocking layer 29
Current does not flow from the p-InP blocking layer 28 to the p-InP blocking layer 28, and the current injected from the p-side electrode 30 is constricted and has a high density, and thus the GRIN-SCH-MQW active layer 3 has a high density.
Flow into. Since the current flows in at a high density, GRIN
The carrier density in the -SCH-MQW active layer 3 is increased, and the luminous efficiency is improved.

The reflecting film 34 on the reflection side has a light reflectance of 80% or more, preferably 98% or more. On the other hand, the emission side reflection film 35 is for preventing reflection of the laser light on the emission side end face. Therefore, the emitting side reflection film 35 has a film structure with a low reflectance,
The light reflectance is 5% or less, preferably about 1%. However, the light reflectance of the emitting side reflection film 35 is optimized depending on the cavity length, and thus may have a value other than these.

The diffraction grating 3a is made of p-GaInAsP. Since the surrounding p-InP spacer layer 24 is made of a semiconductor material different from that of the surrounding p-InP spacer layer 24, a component having a predetermined wavelength in the light generated from the GRIN-SCH-MQW active layer 3 is reflected by the diffraction grating 3a. .

The diffraction grating 3a has a film thickness of 20 nm, and the diffraction grating 3a having a length Lg = 50 μm is provided from the reflection end face of the emission side reflection film 35 toward the reflection side reflection film 34 side. Are periodically formed with a pitch of about 220 nm and select the wavelength of laser light having a center wavelength of 1.48 μm. Here, the diffraction grating 3a improves the linearity of the drive current-optical output characteristic and stabilizes the optical output by setting the multiplication value of the coupling coefficient κ of the diffraction grating and the diffraction grating length Lg to 0.3 or less. (Japanese Patent Application No. 2001-134545)
reference). Further, when the resonator length L is 1300 μm, oscillation occurs in a plurality of oscillation longitudinal modes when the diffraction grating length Lg is about 300 μm or less, so the diffraction grating length Lg is preferably 300 μm or less. By the way, since the oscillation longitudinal mode interval also changes in proportion to the length of the resonator length L, the diffraction grating length Lg has a value proportional to the resonator length L. That is, (diffraction grating length Lg) :( resonator length L) = 300: 1
In order to maintain the relationship of 300, the diffraction grating length Lg is 300
The relationship in which a plurality of oscillation longitudinal modes can be obtained at μm or less can be expanded as Lg × (1300 (μm) / L) ≦ 300 (μm). That is, the diffraction grating length L
g is set so as to maintain the ratio with the resonator length L, and is set to a value equal to or less than (300/1300) times the resonator length L (see Japanese Patent Application No. 2001-134545).

Next, the reason why the semiconductor laser element 2 selects light having a plurality of oscillation longitudinal modes during laser oscillation by providing the diffraction grating 3a will be described. The oscillation wavelength λ ₀ of the semiconductor laser device 2 is
1100 nm to 1550 nm, and the resonator length L is 8
It is set to 00 μm or more and 3200 μm or less.

In general, the mode interval Δλ of the longitudinal mode generated by the resonator of the semiconductor laser device 2 can be expressed by the following equation when the effective refractive index is “n”. That is, Δλ = λ ₀ ² / (2 · n · L). Here, when the oscillation wavelength λ ₀ is 1480 μm and the effective refractive index n is 3.5, the resonator length L is 800 μm.
At this time, the mode interval Δλ of the longitudinal mode is about 0.39 nm.
Thus, when the resonator length is 3200 μm, the mode interval Δλ of the longitudinal mode is about 0.1 nm. That is, the longer the resonator length L, the longer the mode interval Δ in the longitudinal mode.
λ becomes narrower, and the selection condition for oscillating a single oscillation longitudinal mode laser beam becomes stricter.

On the other hand, the diffraction grating 3a selects the longitudinal mode according to its Bragg wavelength. The selected wavelength characteristic of the diffraction grating 3a is represented as an oscillation wavelength spectrum 36 shown in FIG. As shown in FIG. 9, in the semiconductor laser device 2, a plurality of oscillation longitudinal modes are allowed to exist within the wavelength selection characteristic indicated by the half width Δλh of the oscillation wavelength spectrum 36 of the semiconductor laser device having the diffraction grating 3a. ing. Conventional DBR (Distributed Bragg Reflecto)
r) Semiconductor laser device or DFB (Distributed Fee)
dback) In the semiconductor laser device, the cavity length L is 800μ.
If it is m or more, it is difficult to oscillate in a single oscillation longitudinal mode. Therefore, the semiconductor laser device having such a cavity length L is not used. However, in the semiconductor laser device 2, the cavity length L is positively set to 800 μm or more so that the laser output is performed by including a plurality of oscillation longitudinal modes in the half-width Δλh of the oscillation wavelength spectrum 36. . In FIG. 9, three oscillation longitudinal modes 37 to 39 are provided within the half width Δλh of the oscillation wavelength spectrum 36.

Next, the fact that the laser light emitted from the semiconductor laser device 2 has a waveform as shown in FIG. 10B can suppress the occurrence of stimulated Brillouin scattering. In general, stimulated Brillouin scattering is
It occurs when the intensity of light in a narrow constant frequency band exceeds a predetermined value. For example, if the emission wavelength is 1100-
In the case of the semiconductor laser device 2 having a wavelength of 1550 nm, the total light intensity in the frequency band of 20 MHz is about 4 mW.
If it exceeds, the DSF (Dispersion Shi
It is said that stimulated Brillouin scattering occurs in the fted fiber).

Here, in order to simply suppress the occurrence of stimulated Brillouin scattering, the total light intensity may be suppressed.
However, as in the case of the pump light source of an optical fiber amplifier,
Higher optical output of the semiconductor laser device is desirable. Therefore, in order to avoid stimulated Brillouin scattering while increasing the intensity of emitted light, it is possible to increase the light intensity as a whole by oscillating light in a wide frequency band while reducing the light intensity at each frequency. Will be needed.

As shown in FIGS. 10A and 10B, the semiconductor laser device 2 has a plurality of oscillation longitudinal modes, unlike the conventional semiconductor laser device. Therefore, even if the laser light emitted from the semiconductor laser element 2 has the same light intensity as a whole, the peak value of each oscillation longitudinal mode is lower than the conventional value. This means that the light intensity in the predetermined frequency band is lowered, and the stimulated Brillouin scattering occurs when the light intensity in the predetermined frequency band exceeds the threshold value. It can be seen that the occurrence of is effectively suppressed. When the light intensity is the same as a whole, the larger the number of oscillation longitudinal modes is, the lower the peak value of each oscillation longitudinal mode can be. In this case, the semiconductor laser device 2 can further suppress the occurrence of stimulated Brillouin scattering.

Regarding the structure of the semiconductor laser device 2 described above, it is possible to adopt a structure other than that described above for the portions other than the diffraction grating 3a. For example,
The active layer does not necessarily have to have the GRIN-SCH-MQW structure, and may have a simple double hetero structure or a homojunction laser. Further, a single quantum well may be used instead of the multiple quantum well structure. Furthermore, the structure of the entire semiconductor laser device is not a so-called buried heterostructure, but a ridge laser or a SAS.
(Self Aligned Structure) type laser may be used. Furthermore, the conductivity type of each layer may be opposite to the conductivity type described above. That is, a p-type clad layer, GRIN-SCH-MQW, is formed on a p-type substrate.
It is possible to configure a semiconductor laser device that suppresses the occurrence of stimulated Brillouin scattering even with a laminated structure such as an active layer, an n-type spacer layer, and an n-type clad layer.

Here, the grating length L _G of the diffraction grating
Alternatively, the half-width Δλh of the oscillation wavelength spectrum 36 may be changed by changing the coupling coefficient, so that the number of longitudinal modes in the half-width Δλh may be relatively plural.

FIG. 11 is a longitudinal sectional side view showing a schematic structure of the semiconductor laser device 2. This semiconductor laser element differs from the semiconductor laser element 2 in the configuration of the diffraction grating 43 corresponding to the diffraction grating 3a of the semiconductor laser element 2.

The diffraction grating 43 is provided in a predetermined direction from the emission side reflection film 35 having a low light reflectance of 0.1 to 2% to the reflection side reflection film 34 side having a high light reflectance of 80% or more. the length L _G1 fraction, formed in the p-InP spacer layer 24 other than the predetermined length L _G1, the diffraction grating 43 is not formed.

FIG. 12 is a side sectional view in the longitudinal direction showing a schematic structure of a modified example of the semiconductor laser device. This semiconductor laser device has a diffraction grating 44 provided on the reflection side reflection film 34 side instead of the diffraction grating 43 shown in FIG. 11, and has a low reflectance for the reflection side reflection film 34. That is, the diffraction grating 44 has a reflectance of 0.1 to 10.
The reflectance of 1 from the reflection side reflection film 34 having a low light reflectance of 2%.
A p-InP having a length of L _G2 , which is formed to have a predetermined length L _G2 , toward the emitting-side reflection film 35 side having a low light reflectance of ˜5%.
The diffraction grating 44 is not formed on the spacer layer 24.

Further, FIG. 13 is a side sectional view in the longitudinal direction showing a schematic structure of another modification of the semiconductor laser device. This semiconductor laser device employs the configurations of the diffraction grating 43 shown in FIG. 11 and the diffraction grating 44 shown in FIG.

That is, in this semiconductor laser device, the reflection side reflection film having a low light reflectance of 0.1 to 2% is reflected from the emission side reflection film 35 having a low light reflectance of 0.1 to 2%. Diffraction grating 45 formed for a predetermined length L _G3 toward the film 34 side
a and a diffraction grating 45b formed by a predetermined length L _G4 from the reflection side reflection film 34 toward the emission side reflection film 35 side.

The diffraction gratings 43 and 4 shown in FIGS.
By changing the predetermined lengths L _{G1 to} L _G4 of ₄ , 45a and 45b, the half width Δλh of the oscillation wavelength spectrum 36 shown in FIG. 9 is changed even if the mode interval Δλ of the oscillation longitudinal mode is fixed. be able to. That is, in order to widen the half width Δλh of the oscillation wavelength spectrum 36,
It is also effective to shorten the length of the diffraction grating.

In this case, the phase oscillation condition may be shifted depending on the position of the diffraction grating with respect to the resonator, which may deteriorate the laser oscillation characteristics. Therefore, as shown in FIG. When the emission side reflection film 35, which is on the side, is formed as a starting point and extends in the direction of the reflection side reflection film 34 to the middle of the resonator, the emission side reflection film 35 has low reflectance of 0.1 to 2%. A high-reflection coat having a reflectance of 80% or more is applied as the reflection-side reflection film 34. Further, as shown in FIG. 12, when the diffraction grating 44 is formed by extending the reflection side reflection film 34 in the direction of the emission side reflection film 35 to the middle of the resonator, the diffraction grating 44 is formed as a reflection side reflection film 34. A low light reflection coating having a reflectance of 1 to 2% is applied, and a low reflection coating having a reflectance of 1 to 5% is applied as the emitting side reflection film 35.
Further, as shown in FIG. 13, the diffraction gratings 45a, 45
b is the output side reflection film 35 side and the reflection side reflection film 3 respectively.
When it is formed on the fourth side, a low light reflection coat having a reflectance of 0.1 to 2% is applied to both the emission side reflection film 35 and the reflection side reflection film 34.

Further, as shown in FIG. 11, the diffraction grating 4
In the case where 3 is formed on the emission side reflection film 35 side which is the light emission side, the reflectance of the diffraction grating 43 itself is set to a low level, and FIG.
As shown in, when the diffraction grating 44 is formed on the reflection side reflection film 34 side which is the light reflection side, it is preferable to set a high reflectance of the diffraction grating 44 itself. Further, as shown in FIG. 13, when the diffraction grating is formed on both the emission side reflection film 35 side and the reflection side reflection film 34 side, the diffraction grating 45a is formed.
The reflectance of itself is set low, and the reflectance of the diffraction grating 45b itself is set high. Thereby, the diffraction grating 43,
It is possible to reduce the influence of the Fabry-Perot resonator by the reflection-side reflection film 34 and the emission-side reflection film 35 while satisfying the wavelength selection characteristics of 44, 45a, and 45b.

Specifically, in the semiconductor laser device shown in FIG. 11, the oscillation wavelength λ ₀ is 1480 nm, the cavity length L is 1300 μm, the grating length L _G1 of the diffraction grating 43 is 220 μm, and the coupling coefficient κ _LG. (cm ^-1) and the product kappa _LG · L _G1 between grating length L _G1 is 0.093. In the semiconductor laser device shown in FIG. 12, the cavity length L is 1300 [mu] m, the grating length L _G2 of the diffraction grating 44 is 400 [mu] m, is the product kappa _LG · L _G2 of the coupling coefficient kappa _LG and grating length L _G2 2.97. When such diffraction gratings 43 and 44 are applied, the half-value width Δλh of the oscillation wavelength spectrum 36 is 1 to 2 nm, and it is possible to include about 3 to 5 oscillation longitudinal modes within the half-value width Δλh.

In FIGS. 11 to 13, the diffraction grating 4
Although 3, 44, 45a, and 45b are provided on the emission side reflection film 35 side or the reflection side reflection film 34 side, or on the emission side reflection film 35 side and the reflection side reflection film 34 side, the invention is not limited to this.
A diffraction grating having a partial length with respect to the cavity length L may be formed along the RIN-SCH-MQW active layer 3. However, it is preferable to consider the reflectance of the diffraction grating.

As described above, the length of the diffraction grating with respect to the resonator length L is made partial, and the grating length L _G and the coupling coefficient κ _LG of this diffraction grating are appropriately changed to obtain a desired oscillation wavelength spectrum. 36 half width Δλ
It is possible to obtain h, and it is possible to oscillate a laser beam having a plurality of oscillation longitudinal modes within this half width Δλh.

The position of the diffraction grating may be arranged at a position other than that shown in the above-mentioned semiconductor laser device. For example, a diffraction grating may be provided below the GRIN-SCH-MQW active layer 3. More specifically, the diffraction grating may be arranged in any place in the semiconductor laser element as long as it is a region where light exists.

Further, as shown in FIG. 14, GRIN-S
A diffraction grating 46 may be provided on the entire surface along the CH-MQW active layer 3. In this case, the length L of the diffraction grating is the same as the resonator length. The wavelength selection characteristic of the diffraction grating is determined by the coupling coefficient κ and the length L of the diffraction grating. Since the length of the diffraction grating L is long, the coupling coefficient κ can be reduced to obtain a wavelength similar to that of the diffraction grating 43, for example. Selective characteristics can be obtained, and a plurality of oscillation longitudinal modes can be oscillated.

Next, in the above-mentioned semiconductor laser device,
Although the grating period of the diffraction grating 3a was constant,
A chirped grating in which the grating period of the diffraction grating is changed periodically is used to generate fluctuations in the wavelength selection characteristics of the diffraction grating, widen the half-value width Δλh of the oscillation wavelength spectrum, and oscillate within the half-value width Δλh. The number of vertical modes may be relatively plural. That is, as shown in FIG. 15, the half width Δλh is set to the half width wc.
To increase the number of oscillation longitudinal modes included in the half width wc.

FIG. 16 is a side sectional view in the longitudinal direction showing a schematic structure of a modified example of the semiconductor laser device. This semiconductor laser device has a diffraction grating 47 which is a chirped grating in which the grating period of the diffraction grating 3a of the semiconductor laser device described above is periodically changed.

FIG. 17 is a diagram showing periodic changes in the grating period of the diffraction grating 47. As shown in FIG. 17, the diffraction grating 47 has a structure in which the average period is 220 nm and the period fluctuation (deviation) of ± 0.02 nm is repeated in the period C. Due to the periodic fluctuation of ± 0.02 nm, the reflection band of the diffraction grating 47 has a half-value width of about 2 nm, which causes about 3 to 6 oscillation longitudinal modes within the half-value width Δλh of the oscillation wavelength spectrum. be able to.

Further, in this semiconductor laser device, the chirped grating in which the grating period is changed at the constant period C is used. However, the present invention is not limited to this, and the grating period includes the period Λ ₁ (220 nm + 0.02 nm) and the period Λ ₂ ( 220 nm-0.02 nm) may be randomly changed.

Further, as shown in FIG. 18A, a period grating may be provided as a diffraction grating in which the period Λ ₁ and the period Λ ₂ are alternately repeated once. Further, as shown in FIG. 18B, the period Λ ₃ and the period Λ ₄ may be alternately repeated a plurality of times so that the diffraction grating may have periodic fluctuations. Further, as shown in FIG. 18C, a diffraction grating having a plurality of continuous cycles Λ ₅ and a plurality of continuous cycles Λ ₆ may have periodic fluctuations. Further, periods having discretely different values between the periods Λ ₁ , Λ ₃ , Λ ₅ and the periods Λ ₂ , Λ ₄ , Λ ₆ may be complemented and arranged.

As described above, the diffraction grating provided in the semiconductor laser device is formed by a chirped grating or the like.
A period fluctuation of about ± 0.01 to 0.2 nm is given to the average period, whereby the half-value width of the reflection band is set to a desired value and finally the half-value width Δ of the oscillation wavelength spectrum is set.
It is possible to determine λh and output a laser beam including a plurality of oscillation longitudinal modes within the half width Δλh. When the diffraction grating has such a fluctuation, the diffraction grating may be arranged on the entire surface along the active layer.

(Second Embodiment) Next, a second embodiment of the present invention will be described. In the first embodiment described above, one control function is stored in the storage unit 13, and the Peltier cooler 9 is drive-controlled so that the detected temperature Ts that satisfies this control function is obtained. Form 2
In the above, a plurality of control functions corresponding to a plurality of oscillation wavelengths are held, and minute wavelength control of laser light is actively performed.

FIG. 19 is a diagram showing a schematic configuration of a semiconductor laser device according to the second embodiment of the present invention. In FIG. 19, the temperature control unit 52 corresponds to the temperature control unit 12,
It has a storage unit 53 and a wavelength setting unit 54. The storage unit 53 corresponds to the storage unit 13, but the storage unit 1
Different from 3, a plurality of control functions, that is, a control function group FS
Holds S. A desired wavelength to be controlled is set and input to the wavelength setting unit 54.

The temperature control unit 52 takes out the control function corresponding to the wavelength set by the wavelength setting unit 54, changes the control function to be controlled to this control function, and controls the temperature so as to satisfy the changed control function. I do. For example, in Figure 2.
In 0, when the current control function is the control function FS2 and the wavelength set by the wavelength setting unit 54 is λ1, the temperature control unit 52 changes the current control function FS2 to the control function FS1 and then Temperature control is performed by the control function FS1. As a result, for example, when the drive current Iop is 500 mA and the wavelength λ2 and the drive current Iop does not change, the temperature ΔT1 minute (10 ° C. minute) higher detection temperature T is obtained.
The temperature is controlled to be s, and the laser light of wavelength λ1 is output. Similarly, when the wavelength λ3 is set, it is changed to the control function FS3, and the current drive current Iop is 100.
When the driving current Iop is 0 mA and the wavelength is λ2, the temperature is controlled so that the detection temperature Ts is lower by the temperature ΔT2 (18 ° C.), and the laser light of the wavelength λ3 is output. Even if the drive current Iop is different, the temperature is controlled according to the changed control function.

Here, the temperature control processing procedure by the temperature controller 52 will be described with reference to the flowchart shown in FIG. In FIG. 21, a control function group FSS as shown in FIG. 20 is obtained in advance and set and held in the storage unit 53 (step S201). After that, by inputting the setting of the oscillation wavelength λ (step S202), the temperature control unit 52 shifts to temperature control based on the control function corresponding to the set and input oscillation wavelength (step S203), and ends this processing.

The minute wavelength control according to the second embodiment can be applied to a pumping light source used in a Raman amplifier, for example. In Raman amplification of this semiconductor laser device, as shown in FIG. 22A, a plurality of oscillation longitudinal modes are included in the oscillation wavelength spectra LA1 and LA2 of each pumping light source. The gain characteristics of Raman amplification appear on the long wavelength side of about 100 nm, and appear as gain characteristics LB1 and LB2 corresponding to each pumping light source. Therefore,
The combined gain characteristic of these gain characteristics LB1 and LB2 is like a characteristic LC. However, since the gain characteristic is required to be flat over the wavelength band of the amplified light to be input, the gain characteristic LC must be further flattened.

In such a case, the gain characteristic can be flattened by performing the minute wavelength control described above. For example, when the oscillation wavelength spectrum LA2 is shifted to the short wavelength side, the corresponding gain characteristic is also shifted to the short wavelength side, and as a result, the concave portion of the characteristic LC can be flattened.

In the first and second embodiments described above, both the semiconductor laser element 2 and the temperature measuring element 5 are installed via the submounts 4 and 6 provided on the heat sink 7. Not limited, submount 4,6
Alternatively, the semiconductor laser device 2 and the temperature measuring device 5 may be directly installed on the heat sink 7. Alternatively, the submounts 4 and 6 may be integrated, and the semiconductor laser element 2 and the temperature measuring element 5 may be installed on the integrated submount. In these cases, the thermal conductivity between the temperature measuring element 5 and the semiconductor laser element 2 is improved, and the temperature measuring element 5 becomes the semiconductor laser element 2
Since it is possible to quickly and accurately measure the temperature, the temperature control or the wavelength control with higher accuracy can be performed.

(Third Embodiment) Next, an optical fiber amplifier according to a third embodiment of the present invention will be described.
In the third embodiment, the semiconductor laser device shown in the above-described first and second embodiments is applied to a Raman amplifier.

FIG. 23 is a block diagram showing the structure of the Raman amplifier according to the third embodiment of the present invention. This Raman amplifier is used in a WDM communication system. FIG. 23
In this case, this Raman amplifier has a configuration using semiconductor laser devices 60a to 60d having the same configuration as the semiconductor laser devices shown in the first and second embodiments.

The semiconductor laser devices 60a and 60b output laser light having a plurality of oscillation longitudinal modes to the polarization beam combiner 61a via the polarization maintaining fiber 71, and the semiconductor laser devices 60c and 60d are polarized. Laser light having a plurality of oscillation longitudinal modes is output to the polarization combining coupler 61b via the wavefront holding fiber 71. Here, the laser lights oscillated by the semiconductor laser devices 60a and 60b have the same wavelength. The laser light emitted by the semiconductor laser devices 60c and 60d has the same wavelength, but the semiconductor laser device 6
The wavelengths of the laser beams oscillated by 0a and 60b are different. This is because the Raman amplification has polarization dependence, and the polarization combining couplers 61a and 61b output laser light whose polarization dependence is eliminated.

The laser lights having different wavelengths output from the respective polarization combining couplers 61a and 61b are combined by the WDM coupler 62, and the combined laser lights are WDM.
The excitation light for Raman amplification is output to the amplification fiber 64 via the coupler 65. The signal light to be amplified is input to the amplification fiber 64 to which the pumping light is input,
Raman amplified.

The signal light (amplified signal light) that has been Raman-amplified in the amplification fiber 64 passes through a WDM coupler 65 and an isolator 66, and a monitor light distribution coupler 67.
Entered in. The monitor light distribution coupler 67 outputs a part of the amplified signal light to the control circuit 68, and outputs the remaining amplified signal light as output light to the signal light output fiber 70.

The control circuit 68 controls the laser output state of each of the semiconductor laser devices 60a to 60d, for example, the light intensity on the basis of a part of the amplified signal light input, so that the gain band of Raman amplification is flat. Feedback control so that

In the Raman amplifier shown in the third embodiment, the semiconductor laser device 60 shown in the first and second embodiments.
a is used. As described above, since each of the semiconductor laser devices 60a to 60d has a plurality of oscillation longitudinal modes, the polarization maintaining fiber length can be shortened. As a result, it is possible to reduce the size and weight of the Raman amplifier and reduce the cost.

In the Raman amplifier shown in FIG. 23,
The polarization combining couplers 61a and 61b are used.
Alternatively, the semiconductor laser devices 60a and 60c may directly output light to the WDM coupler 62 via the polarization maintaining fiber 71, respectively. In this case, the polarization planes of the semiconductor laser devices 60a and 60c are incident on the polarization plane holding fiber 71 at 45 degrees. Here, as described above, each of the semiconductor laser devices 60a, 60
Since c has a plurality of oscillation longitudinal modes, the polarization maintaining fiber length 71 can be shortened. As a result, it is possible to eliminate the polarization dependence of the optical output from the polarization maintaining fiber 71, and it is possible to realize a more compact Raman amplifier with a smaller number of components.

If a semiconductor laser device having a large number of oscillation longitudinal modes is used as the semiconductor laser devices 60a-60d, the required length of the polarization maintaining fiber 71 can be shortened. Especially when the oscillation longitudinal mode becomes 4 or 5,
Since the required length of the polarization maintaining fiber 71 is drastically shortened, simplification and downsizing of the Raman amplifier can be promoted. Furthermore, as the number of oscillation longitudinal modes increases,
The coherent length becomes shorter, and the degree of polarization (DOP: Degree Of Polarization) becomes smaller due to depolarization.
It becomes possible to eliminate the polarization dependence, which also facilitates simplification and downsizing of the Raman amplifier.

Further, the semiconductor laser device using the semiconductor laser element having the built-in diffraction grating shown in the first and second embodiments described above has a relative intensity noise (compared to the semiconductor laser device using the fiber grating, for example). Since RIN) can be reduced, fluctuations in Raman amplification can be suppressed and stable Raman amplification can be performed.

Further, in this Raman amplifier, the optical axis alignment is easier than in a semiconductor laser module using a fiber grating, and there is no mechanical optical coupling in the resonator. The stability and reliability of can be improved.

Further, the semiconductor laser devices of the first and second embodiments described above are characterized by having a plurality of oscillation longitudinal modes and having a large line width in each oscillation longitudinal mode. Therefore, high-power pumping light can be generated without generating stimulated Brillouin scattering, so that stable and high Raman gain can be obtained.

Although the Raman amplifiers shown in FIGS. 23 and 24 are of the backward pumping type, they are of the forward pumping type because the semiconductor laser devices 60a to 60d output stable pumping light as described above. Also, stable Raman amplification can be performed even with the bidirectional pumping method.

For example, FIG. 25 is a block diagram showing the configuration of a Raman amplifier adopting the forward pumping method. Figure 2
In the Raman amplifier shown in FIG. 5, the WDM coupler 65 'is provided in the vicinity of the isolator 63 in the Raman amplifier shown in FIG. The WDM coupler 65 'includes semiconductor laser devices 60a to 60d, polarization combining couplers 61a and 61b, and semiconductor laser devices 60a' to 60d 'and polarization combining couplers 61a' and 6 corresponding to the WDM coupler 62, respectively.
A circuit including 1b ′ and a WDM coupler 62 ′ is connected to perform forward pumping in which the pumping light output from the WDM coupler 62 ′ is output in the same direction as the signal light. In this case, since the semiconductor laser devices 60a'-60d 'use the semiconductor laser elements shown in the above-described first and second embodiments,
The RIN is small and forward excitation can be effectively performed.

Similarly, FIG. 26 is a block diagram showing the structure of a Raman amplifier adopting the forward pumping method. FIG. 26
In the Raman amplifier shown in FIG. 24, the WDM coupler 65 ′ is provided near the isolator 63 in the Raman amplifier shown in FIG. The WDM coupler 65 ′ includes semiconductor laser devices 60 a ′, 60 c ′ and WD corresponding to the semiconductor laser devices 60 a and 60 c and the WDM coupler 62, respectively.
A circuit having an M coupler 62 ′ is connected to perform forward pumping in which the pumping light output from the WDM coupler 62 ′ is output in the same direction as the signal light. In this case, the semiconductor laser device 60
Since a ′ and 60c ′ use the semiconductor laser device shown in the above-described first and second embodiments, RIN is small and forward pumping can be effectively performed.

FIG. 27 is a block diagram showing the structure of a Raman amplifier adopting the bidirectional pumping method. FIG. 27
The Raman amplifier shown in FIG. 23 has the configuration of the Raman amplifier shown in FIG. 23, the WDM coupler 65 ′ shown in FIG. 25, the semiconductor laser devices 60a ′ to 60d ′, and the polarization combining coupler 61.
Further, a ', 61b' and a WDM coupler 62 'are further provided to perform backward pumping and forward pumping. In this case, since the semiconductor laser devices 60a ′ to 60d ′ use the semiconductor laser elements shown in the above-described first and second embodiments, R
Since IN is small, forward excitation can be effectively performed.

Similarly, FIG. 28 is a block diagram showing the structure of a Raman amplifier adopting the bidirectional pumping method. Figure 2
The Raman amplifier shown in FIG. 8 has the same structure as the Raman amplifier shown in FIG. 24 but has the WDM coupler 65 ′, the semiconductor laser devices 60a ′ and 60c ′ and the WDM coupler 6 shown in FIG.
2'is further provided to perform backward excitation and forward excitation. In this case, since the semiconductor laser devices 60a 'and 60c' use the semiconductor laser elements described in the first and second embodiments, the RIN is small and the forward pumping can be effectively performed.

The Raman amplification light source used for forward pumping in the forward pumping method or the bidirectional pumping method described above may have a resonator length L of less than 800 μm.
When the resonator length L is less than 800 μm, the mode interval Δλ of the oscillation longitudinal mode becomes narrow as described above, and when used as a light source for Raman amplification, the number of oscillation longitudinal modes decreases and a large optical output can be obtained. However, since the forward pump requires a lower output than the backward pump, the resonator length L does not necessarily have to be 800 μm or more.

The Raman amplifiers shown in FIGS. 23 to 28 described above can be applied to the WDM communication system as described above. FIG. 29 is a block diagram showing a schematic configuration of a WDM communication system to which the Raman amplifier shown in FIGS. 23 to 28 is applied.

In FIG. 29, a plurality of transmitters Tx1 to Tx are provided.
The optical signals of wavelengths λ1 to λn transmitted from xn are combined by the optical combiner 80 and integrated into one optical fiber 85. On the transmission path of the optical fiber 85, a plurality of Raman amplifiers 81 and 83 corresponding to the Raman amplifiers shown in FIGS. 23, 24, and 25 to 28 are arranged according to the distance, and the attenuated optical signal is amplified. To do. The signal transmitted on the optical fiber 85 is demultiplexed by the optical demultiplexer 84 into optical signals having a plurality of wavelengths λ1 to λn, and the plurality of receivers Rx1 to Rx are provided.
It is received by xn. On the optical fiber 85, an ADM (Ad (Ad) that adds and takes out an optical signal of an arbitrary wavelength is used.
d / Drop Multiplexer) may be inserted.

Here, in the third embodiment described above, since the semiconductor laser device shown in the first and second embodiments is used, it is possible to output a laser beam having a stable wavelength without oscillation wavelength shift, A flat gain characteristic can be stably maintained, and the gain characteristic can be easily flattened by performing highly accurate wavelength control.

In the third embodiment described above, the semiconductor laser device shown in the first and second embodiments is used as the pumping light source for Raman amplification. However, the present invention is not limited to this and, for example, 0. Obviously, it can be used as a light source for EDFA excitation such as 98 μm. Particularly, in the EDFA in which the transmission distance of the pumping light to the EDF is several kilometers to several tens of kilometers or more, by using the semiconductor laser device according to the first and second embodiments as the pumping light source, the guided Brillouin during the transmission is transmitted. It is possible to effectively suppress a decrease in amplification gain due to scattering.

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described. Embodiments 1 to 3 described above
In the semiconductor laser device used in the semiconductor laser device, the semiconductor laser device has a diffraction grating near the active layer and a plurality of oscillation longitudinal modes. However, in the fourth embodiment, the semiconductor laser device is a Fabry-Perot. Resonance type laser (FP
Laser) element.

FIG. 30 shows Embodiments 1 to 1 of the invention described above.
3 is a longitudinal sectional view of a semiconductor laser element incorporated in the semiconductor laser device used in FIG. In addition, FIG.
It is the sectional view on the AA line of the semiconductor laser element shown in FIG. 30 and 31, the semiconductor laser device 100 is the same as the semiconductor laser device 2 shown in the first embodiment.
Is a configuration excluding the diffraction grating 3a and is an FP laser element that constitutes a so-called Fabry-Perot resonator.

Since this semiconductor laser device 100 is an FP laser device, it has a smaller RIN than a semiconductor laser device using a fiber grating. Therefore, like the semiconductor laser device 2, it is for a forward pumping Raman amplifier. It can be used as an excitation light source. Here, when used as a pumping light source for a Raman amplifier, it is necessary to perform precise control of the oscillation wavelength for stable oscillation.

However, the dependence of the wavelength emitted by the semiconductor laser device 100 on the driving current has a larger dependence on the driving current of the wavelength than that of the semiconductor laser device 2, and the wavelength fluctuation due to the increase or decrease of the driving current is extremely large. Is very large. For example, FIG. 32 shows a semiconductor laser device 2 and a semiconductor laser device 100.
FIG. 3 is a diagram showing the dependency of the drive current on the wavelengths of and, in the range of the drive current of 100 mA to 1300 mA, the semiconductor laser element 2 has a wavelength fluctuation of about several nm, while the semiconductor laser element 100 has several tens of wavelengths. It exhibits a wavelength variation of about nm.

However, by performing the temperature control shown in the first embodiment, the wavelength variation within several nm can be accommodated as shown in FIG. That is, the drive current I
op (A) and the temperature Ts (° C) detected by the temperature measuring element 5
By controlling the temperature so that the relation with Ts = −0.03 × Iop + 50.5.
The temperature of the active layer within 00 is controlled to be substantially constant, and as a result, the oscillation wavelength becomes constant with increase and decrease of the drive current. As a result, even the semiconductor laser device 100, which is an FP laser device having a large dependency on the drive current, can output a laser beam having a stable wavelength regardless of the increase or decrease of the drive current, that is, regardless of the increase or decrease of the output. it can. This function depends on the thermal resistance between the active layer 3 of the semiconductor laser device 100 and the temperature measuring device 5 and the electric resistance of the semiconductor laser device 100.

Of course, similarly to the second embodiment, the oscillation wavelength can be made variable by shifting the relationship between the drive current Iop and the temperature Ts.

In the first to fourth embodiments described above, the semiconductor laser elements 2 and 10 that oscillate a plurality of oscillation longitudinal modes are used.
0 has been described on the premise that it is incorporated in the semiconductor laser device. However, the present invention is not limited to this, and similarly stable wavelength control can be performed even in a semiconductor laser device that oscillates a single longitudinal mode such as a DFB laser or a DBR laser. It can be performed. That is, not only the pump light source for optical fiber amplifier,
By applying the present invention to a signal light source as well, it is possible to easily and inexpensively output laser light having a stable wavelength without dependence on a drive current.

In the above-described first to fourth embodiments, the Raman amplifier has been mainly described as an example, but the present invention is not limited to this, and another optical fiber amplifier pumping light source, for example, ED.
It can also be applied to a FA excitation light source.

[0130]

As described above, according to the first aspect of the invention, the temperature control means is configured such that the temperature of the driving current and the temperature measuring element are such that the wavelength of the laser beam oscillated by the semiconductor laser element is substantially constant in advance. The relationship with the detected temperature to be detected is held, and the temperature adjusting means is controlled so that the detected temperature of the temperature measuring element with respect to the value of the drive current detected by the current detecting means satisfies the above relationship, thereby driving Since the wavelength of the laser light is kept constant regardless of the increase / decrease in the current, it is possible to eliminate the dependence of the oscillation wavelength output from the semiconductor laser device on the drive current, and to provide a stable wavelength with no shift in the oscillation wavelength. There is an effect that the laser light of 1 can be obtained easily, in small size, and at low cost.

According to the second aspect of the present invention, the temperature control means includes the temperature adjusting means for lowering the temperature detected by the temperature measuring element as the drive current detected by the current detecting means increases. Since the relationship is controlled to maintain the above relationship, there is an effect that a laser beam having a stable wavelength can be obtained easily, in a small size, and at a low cost without requiring a wavelength monitor.

Further, according to the invention of claim 3, since the semiconductor laser device is a semiconductor laser device having a built-in diffraction grating and oscillating a plurality of longitudinal modes, a highly accurate and stable gain characteristic is provided. It has an effect that it can be used as a possible excitation light source for Raman amplification.

According to a third aspect of the present invention, the semiconductor laser device is formed into a Fabry-Perot resonator.
Even if the semiconductor laser element oscillates a plurality of longitudinal modes and the oscillation wavelength has a high dependency on the driving current and current, it is possible to obtain the laser light of the stable wavelength easily, in a small size and at a low cost. Play.

Further, according to the inventions of claims 3 to 9, the semiconductor laser device has a built-in diffraction grating and oscillates a plurality of longitudinal modes, so that a desired number of oscillation longitudinal modes can be obtained. It can oscillate laser light, and
It is possible to stably output these oscillation wavelengths.

According to the tenth aspect of the present invention, the relationship between the drive current at which the wavelength of the laser light oscillated by the semiconductor laser element is substantially constant and the detected temperature detected by the temperature measuring element is expressed as follows. Since it is determined as the relationship between the drive current at which the temperature of the active layer of the element is almost constant and the detected temperature detected by the temperature measuring element, the cause of the drive current dependency of the oscillation wavelength can be directly removed. It has the effect of being able to.

According to the eleventh aspect of the present invention, the storage means of the temperature control means is made to hold the relationship, and based on this relationship, the dependency of the oscillation wavelength on the driving current to each semiconductor laser device is eliminated. Since the temperature control is performed, it is possible to perform fine temperature control individually corresponding to each semiconductor laser device.

According to the twelfth aspect of the invention, the temperature control means shifts from one of the relationships currently used to another relationship corresponding to the desired wavelength input and set by the setting means. Since the temperature adjusting means is controlled based on the shifted relationship to control to the desired wavelength, fine wavelength control can be performed with high accuracy, and it is used as a pumping light source for a Raman amplifier. In this case, there is an effect that the gain characteristic such as the flattening of the gain characteristic can be corrected by the wavelength shift.

According to the thirteenth aspect of the present invention, the relation is set as a control function common to a plurality of semiconductor laser device groups having the same structure and operation, and the detected temperature is set for one or more drive currents. Since it is determined as a control function specific to the semiconductor laser device, a control function corresponding to each semiconductor laser device can be obtained easily and accurately, which ensures the dependence of the oscillation wavelength on the drive current. There is an effect that it can be lost.

According to the fourteenth aspect of the invention, since the control function is adapted to perform a simple temperature control by using the detected temperature as a linear function of the drive current, the oscillation wavelength is driven by the simple control. The effect that the current dependency can be eliminated is obtained.

According to the invention of claim 15, the control function is made to correspond to the power consumption in the active layer and the detected temperature is a quadratic function of the drive current. Therefore, the oscillation wavelength of the oscillation wavelength can be controlled by simple control. The effect that the drive current dependency can be effectively eliminated is obtained.

According to the sixteenth to eighteenth inventions,
Since the semiconductor laser device according to any one of claims 1 to 15 is provided with a pumping light source, laser light having a stable oscillation wavelength can be output, and flattened gain characteristics can be maintained. Thus, it is possible to surely flatten the gain characteristic by changing the wavelength. In particular, the RIN is smaller than that of the pumping light source using the fiber grating, so that it is possible to realize the Raman amplifier for forward pumping.

According to the invention of claim 19, first,
By the relationship acquisition step, the relationship between the drive current at which the wavelength of the laser light oscillated by the semiconductor laser element is substantially constant and the detected temperature detected by the temperature measurement element is obtained, and the semiconductor laser element is detected by the current detection step. When a change in the applied drive current is detected, the temperature control step controls the temperature of the semiconductor laser element so that the detected temperature of the temperature measurement element with respect to the value of the drive current detected by the current detection step satisfies the relationship. By repeating the above process, it is possible to eliminate the dependence of the oscillation wavelength output from the semiconductor laser element on the drive current, and to obtain a laser beam with a stable wavelength that does not cause a shift in the oscillation wavelength easily, in a small size, and at low cost. There is an effect that can be obtained.

According to the twentieth aspect of the invention, the relationship is obtained as a relationship between the drive current at which the active layer temperature of the semiconductor laser device is constant and the detected temperature detected by the temperature measuring device. Therefore, it is possible to directly remove the cause of the dependence of the oscillation wavelength on the drive current.

According to the twenty-first aspect of the present invention, the relationship between the drive current at which the wavelength of the laser light oscillated by the semiconductor laser element becomes substantially constant and the detected temperature detected by the temperature measuring element are obtained by the relationship obtaining step. A plurality of relations are obtained, a desired wavelength is set and inputted by the setting input step, and another relation corresponding to the desired wavelength inputted and set by the setting input step is selected from the one relation currently used by the relation shifting step. The relationship is shifted, the change of the driving current applied to the semiconductor laser element is detected by the current detection step, and the relationship of the relationship shifted by the relationship shift step and the driving current detected by the current detection step are detected by the temperature control step. The temperature of the semiconductor element is controlled so that the detected temperature with respect to the value satisfies the relationship shifted by the relationship shifting step. Therefore, it is possible to perform minute wavelength control with high precision, and when used as a pumping light source for a Raman amplifier, it is possible to correct gain characteristics such as flattening the gain characteristics by wavelength shift. Produce an effect.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a semiconductor laser device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an example of a control function stored in a storage unit of the temperature control unit shown in FIG.

3 is a diagram showing a drive current dependency of an oscillation wavelength in the semiconductor laser device shown in FIG.

FIG. 4 is a diagram showing an example in which a control function stored in a storage unit of the temperature control unit shown in FIG. 1 is a quadratic function.

5 is a diagram showing another example of the control function stored in the storage unit of the temperature control unit shown in FIG.

6 is a flowchart showing a procedure of a drive control method of the semiconductor laser device shown in FIG.

FIG. 7 is a schematic perspective view showing the structure of a semiconductor laser device.

FIG. 8 is a side sectional view showing the structure of a semiconductor laser device.

FIG. 9 is a schematic diagram showing a waveform of laser light emitted from a semiconductor laser element having a diffraction grating.

FIG. 10 is a waveform of laser light emitted from a conventional semiconductor laser device having a single oscillation longitudinal mode and a waveform of laser light emitted from the semiconductor laser device of the semiconductor laser device according to the first embodiment of the present invention. It is a schematic diagram which shows.

FIG. 11 is a side sectional view showing a structure of a semiconductor laser device.

FIG. 12 is a side sectional view showing the structure of a semiconductor laser device.

FIG. 13 is a side sectional view showing the structure of a semiconductor laser device.

FIG. 14 is a side sectional view showing the structure of a semiconductor laser device.

FIG. 15 is a schematic diagram showing a waveform of laser light emitted from a semiconductor laser device.

FIG. 16 is a side sectional view showing the structure of a semiconductor laser device.

FIG. 17 is a schematic view showing a structure of a diffraction grating incorporated in a semiconductor laser device.

FIG. 18 is a schematic view showing a modified example of the structure of the diffraction grating.

FIG. 19 is a diagram showing a structure of a semiconductor laser device according to a second embodiment of the present invention.

20 is a diagram showing an example of a control function group stored in a storage unit of the temperature control unit shown in FIG.

21 is a flowchart showing a drive control method procedure of the semiconductor laser device shown in FIG.

22 is a diagram showing a gain characteristic correction process by wavelength control when the semiconductor laser device shown in FIG. 19 is applied to a pumping light source for a Raman amplifier.

FIG. 23 is a block diagram showing a configuration of an optical fiber amplifier.

FIG. 24 is a block diagram showing an application example of an optical fiber amplifier.

FIG. 25 is a block diagram showing a configuration of an optical fiber amplifier adopting a forward pumping method, which is a modification of the optical fiber amplifier.

FIG. 26 is a block diagram showing an application example of an optical fiber amplifier.

FIG. 27 is a block diagram showing a configuration of an optical fiber amplifier adopting a bidirectional pumping method, which is a modification of the optical fiber amplifier.

FIG. 28 is a block diagram showing an application example of an optical fiber amplifier.

FIG. 29 is a block diagram showing a schematic configuration of a WDM communication system using an optical fiber amplifier.

FIG. 30 is a side sectional view showing a structure of a semiconductor laser element mounted on a semiconductor laser device according to a third embodiment of the present invention.

31 is a cross-sectional view taken along the line AA of the semiconductor laser device shown in FIG.

FIG. 32 is a diagram showing a drive current dependency of a wavelength of a semiconductor laser device.

FIG. 33 is a diagram showing the driving current dependence of the wavelength of the semiconductor laser device equipped with the semiconductor laser device shown in FIG. 30.

[Explanation of symbols]

1 Semiconductor laser device 2,100 Semiconductor laser device 3 Active layer 3a diffraction grating 4,6 submount 4a, 6a metal thin film 5 Temperature measuring element 7 heat sink 8 base 9 Peltier cooler 10 variable power supply 11 Current detector 12,52 Temperature controller 13,53 storage 21 n-InP substrate 22 n-InP buffer layer 24 p-InP spacer layer 26 p-InP clad layer 27 p-GaInAsP contact layer 28 p-InP blocking layer 29 n-InP blocking layer 30 p side electrode 31 n-side electrode 34 Reflective film 35 Emitting side reflective film 54 Wavelength setting section Ts temperature Iop drive current FS1 to FS3 control functions

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01S 5/022 H01S 5/022 5/024 5/024 5/125 5/125 (72) Inventor Jun Yoshida Own 2-6-1, Marunouchi, Chiyoda-ku, Tokyo F-term inside Furukawa Electric Co., Ltd. (reference) 2K002 AA02 AB30 BA01 CA15 DA10 EB15 HA24 5F072 AB07 AK06 KK30 PP07 QQ07 YY17 5F073 AA22 AA45 AA65 AA74 AA83 AA89 GA09EA09 BA18 GA09EA GA21

Claims (21)

[Claims] 1. A semiconductor that controls the temperature of the semiconductor laser element based on the temperature detected by a temperature measuring element provided in the vicinity of the semiconductor laser element to control the wavelength of laser light oscillated by the semiconductor laser element. In the laser device, a temperature adjusting means for cooling and heating the semiconductor laser element, a current detecting means for detecting a change in a drive current applied to the semiconductor laser element, and a wavelength of laser light oscillated by the semiconductor laser element Based on the relationship between the drive current and the temperature detected by the temperature measuring element, which are substantially constant, the temperature detected by the temperature measuring element with respect to the value of the drive current detected by the current detecting means satisfies the relationship. A semiconductor laser device comprising: a temperature control unit for controlling the temperature adjusting unit as described above. 2. The temperature control means controls the temperature adjusting means so as to lower the temperature detected by the temperature measuring element as the drive current detected by the current detecting means increases, thereby maintaining the relationship. The semiconductor laser device according to claim 1, wherein: 3. The semiconductor laser device according to claim 1, wherein the semiconductor laser element forms a Fabry-Perot type resonator and oscillates a plurality of longitudinal modes. 4. The semiconductor laser device according to claim 1, wherein the semiconductor laser element has a built-in diffraction grating and oscillates a plurality of longitudinal modes. 5. The diffraction grating has a diffraction grating length of 300 μm.
The semiconductor laser device according to claim 4, wherein the semiconductor laser device has a thickness of m or less. 6. The active layer formed between the first reflection film provided on the emission end face of the laser light and the second reflection film provided on the reflection end face of the laser light. Of the length of the resonator formed by (300/1
The semiconductor laser device according to claim 4, wherein the value is not more than 300 times. 7. The diffraction grating provided on the side of the first reflection film provided on the emitting end face of the laser light or in the vicinity of the first reflection film has a multiplication value of the coupling coefficient of the diffraction grating and the diffraction grating length of 0. It is 3 or less, The semiconductor laser device as described in any one of Claims 4-6. 8. The semiconductor laser device according to claim 4, wherein the diffraction grating has a grating period changed randomly or in a predetermined period. 9. A length of a resonator formed by an active layer formed between a first reflection film provided on a laser light emission end face and a second reflection film provided on a laser light reflection end face. Is 800 μm or more, and
8. The semiconductor laser device according to any one of 8. 10. The relationship is a relationship between the drive current at which the temperature of the active layer of the semiconductor laser device is substantially constant and the detected temperature detected by the temperature measuring device. The semiconductor laser device according to any one of 1. 11. The temperature control unit includes a storage unit that holds the relationship.
The semiconductor laser device according to any one of 1. 12. A setting means for inputting and setting a desired wavelength, and a storage means for holding a plurality of the relations, wherein the temperature control means is set by the setting means from one of the relations currently used. The shift to another relation corresponding to a desired wavelength set by input, and the temperature adjusting means is controlled based on the shifted relation to control to the desired wavelength. 11. The semiconductor laser device according to any one of 10. 13. The relationship is a control function common to a plurality of semiconductor laser device groups having the same structure and operation, and is a control function unique to the semiconductor laser device by setting a detected temperature for one or more drive currents. 13. The semiconductor laser device according to claim 1, wherein the semiconductor laser device is determined as follows. 14. The control function according to claim 13, wherein the detected temperature is a linear function of the drive current.
The semiconductor laser device according to 1. 15. The control function according to claim 13, wherein the detected temperature is a quadratic function of the drive current.
The semiconductor laser device according to 1. 16. A pumping light source comprising the semiconductor laser device according to claim 1, an optical fiber for transmitting signal light, and an amplification optical fiber connected to the optical fiber. An optical fiber comprising: a coupler for making pumping light emitted from the pumping light source incident on an amplification optical fiber; and a pumping light transmitting optical fiber connecting the pumping light source and the coupler. amplifier. 17. The optical fiber amplifier according to claim 16, wherein the amplification optical fiber amplifies light by Raman amplification. 18. The optical fiber amplifier according to claim 17, wherein the Raman amplification is performed by at least a forward pumping method. 19. A semiconductor which controls the temperature of the semiconductor laser element based on the temperature detected by a temperature measuring element provided in the vicinity of the semiconductor laser element to control the wavelength of laser light oscillated by the semiconductor laser element. In a drive control method of a laser device, a relationship acquisition step of obtaining a relationship between the drive current at which the wavelength of laser light oscillated by the semiconductor laser element is substantially constant and the detected temperature detected by the temperature measuring element, and the semiconductor laser A current detection step of detecting a change in drive current applied to the element, and a temperature of the semiconductor laser element so that the detected temperature of the temperature measurement element with respect to the value of the drive current detected by the current detection step satisfies the relationship. A drive control method for a semiconductor laser device, comprising: a temperature control step of controlling. 20. The relationship according to claim 19, wherein the relationship is a relationship between the drive current at which the temperature of the active layer of the semiconductor laser element is constant and the detected temperature detected by the temperature measuring element. Drive control method for semiconductor laser device. 21. A semiconductor which controls the temperature of the semiconductor laser element based on the temperature detected by a temperature measuring element provided in the vicinity of the semiconductor laser element to control the wavelength of laser light oscillated by the semiconductor laser element. In a drive control method for a laser device, a relationship acquisition step of obtaining a plurality of relationships between the drive current at which the wavelength of the laser light oscillated by the semiconductor laser element is substantially constant and the detected temperature detected by the temperature measuring element, and A setting input step of setting and inputting a wavelength; a relationship shifting step of shifting from one of the relationships currently used to another relationship corresponding to a desired wavelength input and set by the setting and input step; and the semiconductor laser A current detecting step of detecting a change in a drive current applied to the element, the relationship shifted by the relationship shifting step, and the current detecting step A temperature control step of controlling the temperature of the semiconductor element so that the detected temperature with respect to the value of the detected drive current satisfies the relationship shifted by the relationship shift step, and the drive control of the semiconductor laser device. Method.