JPH0897516A - Wavelength stabilized external resonator type ld light source - Google Patents

Abstract

PURPOSE: To obtain an external resonator type LD light source, which stabilizes promptly its oscillation wavelength in an arbitrary wavelength, by a method wherein a temperature change of an optical system base table is detected and a parallel moving mechanism is driven by a piezo-element to absorb a change of a resonator length. CONSTITUTION: A temperature detection element 7B is fixed on an optical system base table 5 and detects the temperature of the base table 5 to output the detection temperature to a temperature detection signal processing circuit 9. Whereupon the circuit 9 carries out a comparison operation of a temperature detection value at the reference temperature of the base table 5 and a temperature detection value based on a temperature change to output the result of the comparison operation. A piezo- element use voltage control circuit 10 uses the output of the circuit 9 as the input and inputs a voltage in a piezo-element 8 to micromove and control a parallel moving mechanism 6 in a resonator direction. Thereby, as the position of a diffraction grating 4 is adjusted by a correction control of the element 8 at the amount of change of a resonator length to correspond to the amount, which is thermally expanded and changed by a temperature change, of the base table 5, a change of the resonator length is absorbed and the oscillation wavelength of an LD light source is stabilized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an external resonator type LD light source used in the field of optical coherent communication / optical measurement technology.

[0002]

2. Description of the Related Art In order to use it in optical coherent communication and optical measurement technology, a single mode oscillation LD light source capable of wavelength tunability, narrow spectral line width and good wavelength stability is required. The structure of the single mode oscillation LD light source includes a monolithic LD structure in which a diffraction grating is formed in the waveguide inside the LD element and an external resonator type LD structure in which a reflecting mirror such as a diffraction grating is arranged outside the LD element. It can be roughly divided into structures.

Next, the oscillation wavelength operation of the LD light source in the external resonator type LD light source using the diffraction grating will be briefly described with reference to FIG. In FIG. 6, 1 is a laser diode (hereinafter referred to as LD light source), 1A is a non-reflective film, 2 is a lens, 3 is an optical isolator, 4 is a diffraction grating, and 20 is an LD.
It is a drive circuit. In FIG. 6, the LD light source 1 driven by the LD drive circuit 20 uses, for example, a Fabry-Perot type semiconductor laser, one end face of which is provided with a non-reflection film 1A, and the light emitted from the end face provided with the non-reflection film 1A is emitted. The incident light is the lens 2
Is converted into parallel light by and is incident on the diffraction grating 4. At this time, an external resonator having a resonator length L is formed by the diffraction grating 4 and the other end surface of the LD light source 1 where the non-reflection film 1A is not applied, and the LD light source 1 oscillates in a single mode. , The output light is output from the other end face.

The oscillation wavelength of the LD light source 1 is given by the relationship shown in the following formula, and the oscillation wavelength is such that the mirror loss is small in the vicinity of the Bragg wavelength λ _b of the diffraction grating 4 and there is a phase condition due to the optical resonator. . λ _M = 2 × n × L / M Phase condition (resonance wavelength) ………… (1) λ _b = 2 × d × sin (θ) / m Bragg wavelength ………… (2)

In the equations 1 and 2, λ _M is the resonance wavelength in the external resonator, M is the number of longitudinal modes (integer) in the external resonator, and L
The external cavity length, n is the refractive index of the external cavity, lambda _b is the Bragg wavelength, d is the groove spacing of the diffraction grating, theta is the angle of incidence (Littrow configuration) of the diffraction grating, m is the reflected light orders of diffraction grating (Usually m = 1).

From the relationship of Equation 1 and Equation 2, the external resonator type LD light source using the diffraction grating 4 changes the angle of the diffraction grating 4 and the incident angle θ to the diffraction grating 4 to change the LD. The oscillation wavelength of the light source 1 can be changed. However, the wavelength stability of the external resonator type LD light source depends on the stability of the resonance wavelength due to the change of the refractive index n and the resonator length L of the formula 1, and depends on how to suppress the change of the refractive index and the change of the resonator length. The wavelength stability of the LD light source is determined. The Bragg wavelength λb of the monolithic LD is determined by the angle of incidence on the diffraction grating 4.
Instead of sin (θ), the refractive index n of the resonator is substituted.

In order to stabilize the wavelength of the LD light source, a method of controlling the temperature of the entire light source resonator with high accuracy and an optical element (Fabry-Perot etalon or absorption line cell) serving as a wavelength reference are provided outside the light source. There is a method of locking the wavelength of the light source to the reference wavelength of the optical element.

Next, FIG. 6 shows the configuration of a wavelength stabilization circuit for an external resonator type semiconductor laser by temperature control. 6, 1 is an LD light source, 2 is a lens, 1A is a non-reflective film, 3 is an optical isolator, 4 is a diffraction grating, 5 is an optical system base, and 7A.
7B is a temperature detecting element, 11 is a temperature control circuit, 12A
12B is a Peltier element, and 20 is an LD drive circuit. In FIG. 6, LD 1, lens 2 and diffraction grating 4 are external resonator type L
It constitutes a D light source and is configured on the optical system base 5.

In FIG. 6, a temperature detecting element 7A is arranged in the vicinity of LD1 and detects a temperature change of LD1. The temperature control circuit 11 receives the output of the temperature detection element 7A as an input and controls the Peltier element 12A arranged in the vicinity of the LD1 so that the LD
1 is a constant temperature. Similarly, the temperature detecting element 7B is arranged on the optical system base table 5 on the external resonator side, and detects a temperature change of the optical system base table 5. The temperature control circuit 11 receives the output of the temperature detecting element 7B as an input and controls the Peltier element 12B arranged on the optical system base 5 to keep the optical system base 5 at a constant temperature.

By the above operation, the temperature dependence of the cavity length change of the light source cavity is suppressed to stabilize the wavelength. Figure 6
Prior art external resonator type L using the diffraction grating 4 shown in FIG.
D light source is IEICE TRANS. COMMUN., VOL.E75-B, NO.6 JU
It is also described in NE 1992 P521-523.

Next, FIG. 7 shows the configuration of a wavelength stabilization circuit for an external cavity type semiconductor laser using a reference wavelength. 7, 6 is a parallel movement mechanism, 8 is a piezo element, 10 is a voltage control circuit for the piezo element, 12C is a Peltier element, 17 is a Fabry-Perot etalon, 18A and 18B are photodetectors, 19 is an optical signal processing circuit, 22A 22B is a beam splitter.

In FIG. 6, in order to stabilize the wavelength, the temperature of the LD 1 is stabilized, and the change in the resonator length due to the thermal expansion of the optical system base 5 is detected by the temperature detecting element 7B. Peltier device 1 by control circuit 11
This is achieved by controlling 2B to suppress the temperature change, but in FIG. 7, the change in the resonator length due to the thermal expansion of the optical system base 5 is absorbed by the piezo element 8 to stabilize the wavelength. Is.

In FIG. 7, the temperature control of the LD1 is the same as in FIG. The diffraction grating 4 is fixed on the parallel moving mechanism 6, and the piezo element 8 is fixed on the parallel moving mechanism 6 in the optical axis direction of the LD 1. The beam splitter 22A splits a part of the output light of the optical isolator 3. Beam splitter 22
B splits the output light of the beam splitter 22A, one of which is incident on the photodetector 18B and the other of which is incident on the photodetector 18A via the Fabry-Perot etalon 17. The Fabry-Perot etalon 17 is an optical element provided outside the light source and serving as a wavelength reference.

The optical signal processing circuit 19 detects the abrupt change of the transmitted light intensity near the resonance peak wavelength of the Fabry-Perot etalon 17 and the output P _{T of the} photodetector 18A and the photodetector 18B.
Of an input the output P _m, to control the piezoelectric element voltage control circuit 10 so that P _T / P _m is constant, the piezo element 8
A voltage is applied to the parallel moving mechanism 6 to move the parallel moving mechanism 6 in parallel, and the change in the resonator length due to the thermal expansion of the optical system base 5 is absorbed. As shown in FIG. 7, the configuration in which the wavelength of the light source is locked to the reference wavelength of the optical element is also described in 1988 IEICE Spring National Convention C-396 and the like.

[0015]

The wavelength stabilization method by temperature control is intended to stabilize the wavelength by suppressing the temperature dependence of the change in the resonator length of the light source resonator section, and the DFB (Distr
ibuted Freedback) -LD and DBR (Distributed Bragg)
In the case of a monolithic LD light source such as a Reflector) -LD, since the LD element itself is small, it is possible to perform highly accurate temperature control of 0.01 ° C. or less and wavelength stabilization, but in the configuration of FIG. It is difficult to accurately control the temperature of the entire optical system, and the wavelength stability deteriorates.

Further, in the configuration of FIG. 7, since the Fabry-Perot etalon 17 has temperature dependency like the LD light source, the temperature detection by the temperature detection element 7D and the Peltier element for keeping the temperature of the Fabry-Perot etalon 17 constant. It requires high-precision temperature control by 12C, and has a resonance peak wavelength interval determined by the cavity length of the Fabry-Perot etalon 17 as well as the resonance wavelength of the LD light source, so wavelengths other than the peak wavelength of the Fabry-Perot etalon 17 It cannot be stabilized. By changing the control temperature, it is possible to stabilize wavelengths anywhere, but it takes time until the temperature stabilizes,
There is a problem that the wavelength cannot be stabilized immediately.

According to the present invention, the cavity length of the Fabry-Perot etalon 17 does not have to be controlled with high accuracy in temperature control of the entire optical system base 5, and the resonator length of the Fabry-Perot etalon 17 is the same as when an optical element such as the Fabry-Perot etalon 17 is used. It is an object of the present invention to provide an external resonator type LD light source which is not only wavelength-stabilized only by the resonance peak wavelength determined by, but has a simple configuration and instantly stabilizes at an arbitrary wavelength.

[0018]

In order to achieve this object, the present invention provides a non-reflective film 1A on one end surface,
An LD light source 1 driven by a D drive circuit 20, a lens 2 for converting light emitted from the LD light source 1 into parallel light, and an antireflection film 1.
A diffraction grating 4 on which the emitted light emitted from the end face provided with A enters is provided on the optical system base 5, and the diffraction grating 4 and L
An external resonator is formed with the other end face of the D light source 1 on which the antireflection film 1A is not applied, and the temperature detecting circuit 7A provided near the LD light source 1 detects the temperature and the temperature control circuit 11 causes the Peltier device to detect the temperature. In the external resonator type LD light source that controls the element 12A to suppress the temperature change of the LD light source 1 and outputs the emitted light from the other end face, it is fixed to the optical system base 5.
A parallel moving mechanism 6 for moving the diffraction grating 4 in the resonator direction,
The temperature detection element 7B which is provided on the optical system base 5 and detects the temperature of the optical system base 5, the temperature detection signal processing circuit 9 which receives the output of the temperature detection element 7B as an input, and the temperature detection signal processing circuit 9 A piezo element voltage control circuit 10 for controlling the voltage of the piezo element 8 with the output as an input, and a piezo element 8 for driving the parallel movement mechanism 6 in the resonator direction with the output of the piezo element voltage control circuit 10 as the input. The temperature change of the optical system base 5 is detected, and the parallel movement mechanism 6 is driven by the piezo element 8 to absorb the change of the resonator length and stabilize the wavelength.

Further, a temperature detecting element 7B provided on the optical system base 5 for detecting the temperature of the optical system base 5, a temperature detection signal processing circuit 9 to which the output of the temperature detecting element 7B is input, and an LD light source. 1 and the diffraction grating 4 and a plane-parallel substrate 13 that transmits the light emitted from the LD light source 1, and an angle adjustment drive circuit 15 that receives the output of the temperature detection signal processing circuit 9 as an input.
And an angle adjusting mechanism 14 that is fixed on the optical system base 5 with a parallel plane substrate 13 and receives an output of the angle adjusting drive circuit 15 as an input, detects a temperature change of the optical system base 5, and detects the angle. The adjustment mechanism 14 controls the angle of the plane-parallel substrate 13 to absorb the change in the resonator length and stabilize the wavelength.

Alternatively, an LD light source 1 which is provided with an anti-reflection film 1A on one end face and is driven by an LD drive circuit 20, and L
A lens 2 for converting the emitted light of the D light source 1 into parallel light, a beam splitter 16 for entering the emitted light emitted from the end face provided with the antireflection film 1A, and a reflecting mirror for reflecting the reflected light of the beam splitter 16 21 and a diffraction grating 4 that receives the reflected light of the reflecting mirror 21 that has passed through the beam splitter 16 are provided on the optical system base 5, and the temperature is detected by the first temperature detecting element 7A provided near the LD light source 1. Then, in the external resonator type LD light source that controls the Peltier element 12A by the temperature control circuit 11 to suppress the temperature change of the LD light source 1 and outputs the emitted light from the other end face, it is fixed to the optical system base 5. A parallel movement mechanism 6 for moving the reflecting mirror 21 in the resonator direction, a temperature detection element 7B for detecting the temperature of the optical system base 5, and a temperature detection signal processing circuit 9 for receiving the output of the temperature detection element 7B as an input. The output of the temperature detection signal processing circuit 9 is input, the output of the piezoelectric element voltage control circuit 10 for controlling the voltage of the piezoelectric element 8 and the output of the piezoelectric element voltage control circuit 10 are input, and the parallel movement mechanism 6 is set in the resonator direction. The piezo element 8 which is driven to detect the temperature change of the optical system base 5 is used to drive the parallel movement mechanism 6 by the piezo element 8 to absorb the change of the resonator length and stabilize the wavelength.

Further, a plurality of temperature detecting elements are provided on the optical system base 5 to detect the temperature of the optical system base 5 at a plurality of portions, and the temperature detection signal processing circuit 9 receives the output of each temperature detecting element as an input. , The piezo element 8 is controlled by the average value to correct the temperature distribution generated in the resonator direction of the optical system base 5.

[0022]

1 is a block diagram of the first embodiment according to the present invention. 1, 1 is an LD light source, 2 is a lens, 3 is an optical isolator, 4 is a diffraction grating, 5 is an optical system base,
6 is a parallel movement mechanism, 7A and 7B are temperature detection elements, 8 is a piezo element, 9 is a temperature detection signal processing circuit, 10 is a piezo element voltage control circuit, 11 is a temperature control circuit, 12A is a Peltier element, and 20 is an LD. It is a drive circuit.

In FIG. 1, the LD light source 1 is provided with a non-reflective film 1A on one end face thereof, and light emitted from the end face side of the non-reflective film 1A is
It is converted into parallel light by the lens 2. As the lens 2, it is preferable to use an aspherical lens or a combination lens having a small wavefront aberration. A temperature detection element 7A such as a thermistor or a thermocouple and a Peltier element 12A are attached to the LD light source 1, the lens 2, and the LD portion of the optical isolator 3, and the temperature control circuit 11 accurately controls the temperature. Further, a diffraction grating 4 is provided on the non-reflection film 1A side, and an external resonator is formed with the end face of the LD 1 on which the non-reflection film 1A is not provided. The diffraction grating 4 is installed on a parallel moving mechanism 6 composed of a linear stage, a parallel leaf spring mechanism, etc., and finely moved in the resonator direction by a piezo element 8.

The temperature detecting element 7B is fixed on the optical system base 5 to detect the temperature of the optical system base, and the detection signal is input to the temperature detection signal processing circuit 9. The temperature detection signal processing circuit 9 compares and outputs the value of the temperature detection signal at the reference temperature of the optical system base 5 and the value of the temperature detection signal due to the temperature change. The piezoelectric element voltage control circuit 10 receives the output of the temperature detection signal processing circuit 9 as an input and inputs a voltage to the piezoelectric element 8 to finely control the parallel movement mechanism 6 in the resonator direction.

As a result, the optical system base 5 can be changed by the temperature change.
The amount of change in resonator length corresponding to the change in thermal expansion of
Since the position of the diffraction grating 4 is adjusted by the correction control of 1, the change in the resonator length is absorbed and the oscillation wavelength of the LD light source 1 is stabilized. The diffraction grating 6 is provided with an angle adjusting mechanism (not shown), and the wavelength of the tunable LD light source can be obtained by adjusting the angle of the diffraction grating 6.

Next, the configuration of another embodiment of the present invention is shown in FIG. In FIG. 2, instead of the piezo element 8 and the piezo element voltage control circuit 10 of FIG. 1, a parallel plane substrate 13 provided with a double-sided anti-reflection film on the resonator between the diffraction grating 4 and the lens 2 is angled. It was inserted with. The angle of the parallel plane substrate 13 is adjusted by the angle adjusting mechanism 14. In FIG. 2, a temperature detection element 7B is provided on the optical system base 5, a signal of the temperature detection element 7B is processed by the temperature detection signal processing circuit 9, and an angle adjustment drive circuit 15 drives the angle adjustment mechanism 14. The angle adjusting mechanism 14 adjusts the angle of the plane-parallel substrate 13 by a control signal from the angle adjusting drive circuit 15.

The plane-parallel substrate 13 is a glass plate that transmits light, and has a thickness of L ₁ and a refractive index of n.
Then, the optical distance L = transmitted through the plane-parallel substrate 13 =
nL ₁ , the parallel plane substrate 13 is tilted to change the physical distance through which light is transmitted, and the resonator length change amount corresponding to the thermal expansion change of the optical system base 5 due to the temperature change is calculated. The oscillation wavelength of the LD light source 1 is stabilized by making a correction by changing the angle of the substrate 13.

Next, the configuration of another embodiment according to the present invention is shown in FIG. In FIG. 3, an external resonance reflector is formed by the diffraction grating 4, the beam splitter 16, and the reflecting mirror 21, and is arranged as an external mirror on the non-reflection film 1A side. The parallel light from the non-reflective film 1A side is resonated by the external resonance reflector by the beam splitter 21, and is returned to the LD light source 1 by the beam splitter again to narrow the spectral line width of the LD light source 1.

The reflecting mirror 21 is arranged on the parallel moving mechanism 6 so that it can be finely moved in the resonator direction by the piezo element 8. The temperature detecting element 7B detects the temperature of the optical system base 5 to detect the temperature detection signal. The piezo element is controlled through the processing circuit 9 and the piezo element voltage control circuit 10, and the parallel movement mechanism 6
Is finely controlled in the resonator direction. Therefore, the oscillation wavelength of the LD light source 1 is stabilized by controlling the piezo element 8 and adjusting the position of the reflecting mirror 21 by the amount of change in the resonator length corresponding to the thermal expansion change of the optical system base 5 due to the temperature change. To obtain a narrow spectral linewidth.

FIG. 4 shows an example in which a plurality of temperature detecting elements are provided on the optical system base 5 in the configuration of FIG.
This is effective when the optical system base 5 has a temperature distribution and the temperature does not change uniformly. In FIG. 4, a temperature detecting element 7C is provided in the vicinity of the diffraction grating 4 of the optical system base 5 to measure the measurement point 1
The temperature detection element 7B is provided near the LD light source 1 to detect the temperature as the measurement point 2.

FIG. 5 is a temperature characteristic diagram for each measurement point obtained by the configuration of FIG. In FIG. 5, the characteristic of each measurement point is averaged by the processing of the temperature detection signal processing circuit 9, and the resonator length is corrected as a change in the resonator length due to the temperature change at the average value.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a specific embodiment according to the present invention will be described with reference to FIG. In Fig. 1, if an iron-based material with a linear expansion coefficient α of about 1.2 × 10 ^-5 / ° C is used for the optical system base 5 and the oscillation wavelength is around 1550 nm and the external cavity length is 30 mm, the temperature is 1 ° C. The cavity length variation ΔL and the wavelength variation Δλ are ΔL = 360 nm, Δλ = 18.6 pm
(At optical frequency, Δf = 2.32GHz). If the temperature change of the optical system base 5 can be controlled to 0.1 ° C.,
ΔL = 36 nm and Δλ = 1.86 pm (Δf = 232 MHz) are obtained. Furthermore, if the optical system base 5 uses an Invar material having a smaller linear expansion coefficient (α = about 0.2 × 10 ⁻⁵ / ° C.) and the temperature can be controlled at 0.1 ° C., ΔL = 6n
m, Δλ = 0.31 pm (Δf = 38.7 MHz).

The temperature detecting element 7B for detecting the temperature change of the optical system base 5 has a measurement temperature resolution of 0.01 ° C. or less, and the piezo element 8 for finely moving the parallel moving mechanism 6 is
Since it has a displacement amount of 5 μm to hundreds of tens of μm and a positioning resolution of nm unit, the resonator change amount of the LD light source 1 can be corrected in nm unit, and the wavelength change amount is Δλ <0.1 pm.
Is obtained.

[0034]

According to the present invention, the resonator length change due to the thermal expansion due to the temperature change of the optical system base on which the external resonator is constructed is corrected without using a highly accurate temperature control circuit. Therefore, it is not necessary to control the temperature of the entire optical system base with high accuracy, and the structure for stabilizing the oscillation wavelength of the LD light source can be simplified. Even in the case of a tunable LD light source, the resonator length change due to the thermal expansion due to the temperature change of the optical system base table in which the external resonator is configured is corrected without using the wavelength reference optical element. The wavelength can be stabilized immediately not only by the resonance peak wavelength but also by an arbitrary wavelength in the variable wavelength band.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a configuration diagram of a second embodiment of the present invention.

FIG. 3 is a configuration diagram of another embodiment of the present invention.

FIG. 4 is a diagram showing an example in which a plurality of temperature detection elements of FIG. 1 are provided.

5 is a temperature characteristic diagram for each measurement point obtained by the configuration of FIG.

FIG. 6 is an explanatory diagram of an oscillation wavelength operation of an LD light source in an external resonator type LD light source using a diffraction grating.

FIG. 7 is a configuration diagram of a wavelength-stabilized external resonator type LD light source using a reference wavelength.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 LD light source 1A Non-reflective film 2 Lens 3 Optical isolator 4 Diffraction grating 5 Optical system base 6 Translation mechanism 7A-7C Temperature detection element 8 Piezo element 9 Temperature detection signal processing circuit 10 Piezo element voltage control circuit 11 Temperature control circuit 12 Peltier element 13 Parallel plane substrate 14 Angle adjustment mechanism 15 Angle adjustment drive circuit 16 Beam splitter 17 Fabry-Perot etalon 18A ・ 18B Photodetector 19 Optical signal processing circuit 20 LD drive circuit 21 Reflector 22A ・ 22B Beam splitter

Claims (4)

[Claims] 1. A non-reflective film (1A) is applied to one end surface of the LD.
LD light source (1) driven by drive circuit (20) and LD light source
A lens (2) for converting the emitted light of (1) into parallel light and a diffraction grating (4) for entering the emitted light emitted from the end face provided with the antireflection film (1A) are provided on an optical system base ( 5) An external resonator is formed by the diffraction grating (4) and the other end face of the LD light source (1) on which the non-reflective film (1A) is not provided, and the LD light source (1) is provided.
The temperature control circuit (11) controls the Peltier element (12A) to detect the temperature with the first temperature detection element (7A) provided near the In the external resonator type LD light source that outputs the emitted light from the end face, the parallel movement mechanism (6) that moves the diffraction grating (4) toward the resonator is fixed to the optical system base stand (5), and the optical system base stand. (5) A second temperature detecting element (7B) provided on the optical system base (5) for detecting the temperature, and a temperature detection signal processing circuit to which the output of the second temperature detecting element (7B) is input Piezo element voltage control circuit (10) that controls the voltage of the piezo element (8) by using (9) and the output of the temperature detection signal processing circuit (9) as input
And the piezo element (8) that drives the parallel movement mechanism (6) toward the resonator by using the output of the piezo element voltage control circuit (10) as input, and detects the temperature change of the optical system base (5). Piezo element
(8) A wavelength stabilizing external resonator type LD light source, characterized in that the parallel moving mechanism (6) is driven by (8) to absorb a change in resonator length and stabilize the wavelength. 2. A non-reflective film (1A) is applied to one end surface of the LD
LD light source (1) driven by drive circuit (20) and LD light source
A lens (2) for converting the emitted light of (1) into parallel light and a diffraction grating (4) for entering the emitted light emitted from the end face provided with the antireflection film (1A) are provided on an optical system base ( 5) An external resonator is formed by the diffraction grating (4) and the other end face of the LD light source (1) on which the non-reflective film (1A) is not provided, and the LD light source (1) is provided.
The temperature control circuit (11) controls the Peltier element (12A) to detect the temperature with the first temperature detection element (7A) provided near the In the external resonator type LD light source which outputs the emitted light from the end face, the second temperature detecting element (7B) provided on the optical system base table (5) for detecting the temperature of the optical system base table (5), It is arranged between the LD light source (1) and the diffraction grating (4) and the temperature detection signal processing circuit (9) that receives the output of the temperature detection element (7B) of No. 2 as the input.
It is equipped with a parallel plane substrate (13) that transmits the emitted light of (1), an angle adjustment drive circuit (15) that receives the output of the temperature detection signal processing circuit (9), and a parallel plane substrate (13). It is fixed on the system base base (5) and equipped with an angle adjustment mechanism (14) that receives the output of the angle adjustment drive circuit (15) as an input. It detects the temperature change of the optical system base base (5) and detects the angle adjustment mechanism.
A wavelength-stabilized external resonator type LD light source, characterized in that the angle of the plane-parallel substrate (13) is controlled by (14) to absorb changes in the resonator length and stabilize the wavelength. 3. A non-reflective film (1A) is applied to one end surface of the LD
LD light source (1) driven by drive circuit (20) and LD light source
A lens (2) for converting the emitted light of (1) into parallel light, a beam splitter (16) for entering the emitted light emitted from the end face provided with the antireflection film (1A), and a beam splitter (16) A reflecting mirror (21) for reflecting the reflected light of and a diffraction grating (4) for entering the reflected light of the reflecting mirror (21) that has passed through the beam splitter (16) are provided on the optical system base (5), An LD light source in which a Peltier element (12A) is controlled by a temperature control circuit (11) by detecting temperature with a first temperature detection element (7A) provided in the vicinity of the LD light source (1)
In the external resonator type LD light source that suppresses the temperature change of (1) and outputs the emitted light from the other end face, fix it to the optical system base (5) and move the reflecting mirror (21) toward the resonator. The parallel movement mechanism (6), the second temperature detection element (7B) that detects the temperature of the optical system base (5), and the temperature detection signal that receives the output of the second temperature detection element (7B) Piezo element voltage control circuit (10) that receives the output of the processing circuit (9) and the temperature detection signal processing circuit (9) and controls the voltage of the piezo element (8).
And a piezo element (8) that drives the parallel movement mechanism (6) toward the resonator by using the output of the piezo element voltage control circuit (10) as input, and detects the temperature change of the optical system base (5). Piezo element
(8) A wavelength stabilizing external resonator type LD light source, characterized in that the parallel moving mechanism (6) is driven by (8) to absorb a change in resonator length and stabilize the wavelength. 4. A plurality of temperature detecting elements are provided on the optical system base (5) to detect the temperature of the optical system base (5) at a plurality of parts, and the temperature detection signal processing circuit (9) detects each temperature. Input the output of the element, control the piezo element (8) by the average value,
The wavelength stabilized external resonator type LD light source according to claim 1, wherein the temperature distribution generated in the resonator direction of the optical system base (5) is corrected.