JP3733731B2 - Wavelength tunable light source device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wavelength tunable light source device having a function of controlling the output level of emitted light constantly according to a variable wavelength.
[0002]
[Prior art]
Conventionally, an external resonator type semiconductor laser (hereinafter referred to as an LD) is usually used as a wavelength tunable light source, and an optical filter that is a wavelength selection element is inserted into the external resonator. Mode oscillation is obtained. A wide range of wavelength sweeping is possible by mechanically varying the transmission (or reflection) wavelength of the optical filter.
[0003]
An example of a wavelength tunable light source device using such a wavelength tunable light source will be described with reference to the block diagram shown in FIG. The wavelength variable light source device 1 shown in FIG. 4 includes a wavelength variable light source unit 2, a wavelength variable drive unit 3, a drive control unit 4, a control unit 5, a CPU 6, a ROM 7, an LD drive unit 8, and a light detection unit 9. Yes.
[0004]
The wavelength tunable light source unit (TLS) 2 uses an external resonator type LD. When the mechanical position of the optical filter constituting the external resonator is moved by the wavelength tunable drive unit 3, its external resonance is achieved. The conditions are varied, and the wavelength of the emitted light can be varied over a wide range.
[0005]
The wavelength tunable drive unit 3 is composed of a pulse motor or the like, and variably drives the mechanical position of the optical filter in the wavelength tunable light source unit 2 in accordance with a drive control signal input from the drive control unit 4, and also moves its position. Is output to the drive control unit 4 as a rotary encode signal of the pulse motor. The drive control unit 4 generates a drive control signal according to the wavelength variable control signal input from the control unit 5 and outputs the drive control signal to the wavelength variable drive unit 3, and a position signal (rotary encode signal) input from the wavelength variable drive unit 3. ) To the control unit 5.
[0006]
The control unit 5 has a control function for controlling the relationship between the movement position of the optical filter in the wavelength tunable light source unit 2 and the wavelength of the emitted light, and generates a wavelength variable control signal according to the wavelength variable instruction signal input from the CPU 6. Output to the drive control unit 4 to set the wavelength of the emitted light, and confirm that the emitted light has reached the set wavelength based on the position signal (rotary encode signal) input from the drive control unit 4. Stop control. The control unit 5 converts the position signal (rotary encode signal) input from the drive control unit 4 into position data and outputs the position data to the CPU 6.
[0007]
A CPU (Central Processing Unit) 6 outputs a wavelength variable instruction signal to the control unit 5 to instruct to change the wavelength of the emitted light, and sets the set wavelength of the emitted light based on the position data input from the control unit 5. The drive current supplied from the LD drive unit 8 to the variable wavelength light source unit 2 is calculated and read from the ROM 7 and supplied to the LD drive unit 8 with a wavelength correction value for correcting the optical output level based on the set wavelength. Let the amount be corrected.
[0008]
A ROM (Read Only Memory) 7 stores a wavelength calculation processing program executed by the CPU 6 and outputs the output level of the emitted light from the wavelength variable light source unit 2 corresponding to each position data input from the control unit 5 to the CPU 6. A wavelength correction table in which a plurality of wavelength correction values for correcting the wavelength is set is stored.
[0009]
The LD drive unit 8 supplies a drive current to the LD in the wavelength tunable light source unit 2 based on the photodetection signal input from the photodetection unit 9 to control the output level of the emitted light to be constant and is supplied from the CPU 6. Even if the wavelength of the emitted light from the wavelength tunable light source unit 2 is varied by correcting the drive current so as to correct the light detection characteristic according to the wavelength in the light detection unit 9 according to the wavelength correction value to be output. Is controlled to be constant.
[0010]
The light detection unit 9 includes a lens 9a and a light detection element 9b, and the lens 9a uses the reference light input from the wavelength variable light source unit 2 via the optical fiber 10 through the optical connection terminal 12 as parallel light. The light is emitted to the detection element 9b. The light detection element 9b receives incident light from the lens 9a, converts it into a light detection signal of a predetermined voltage level according to the light intensity received with the light receiving sensitivity characteristic according to the wavelength, and converts the light from the detection terminal 13 to the cable. 14 to the LD drive unit 8.
[0011]
As described above, in the conventional wavelength tunable light source device 1 shown in FIG. 4, the CPU 6 always monitors the movement position in the wavelength tunable drive unit 3 and is supplied from the LD drive unit 8 to the wavelength tunable light source unit 2. Is corrected and controlled according to the wavelength.
[0012]
[Problems to be solved by the invention]
However, in such a conventional wavelength tunable light source device 1 of FIG. 4, the CPU 6 always monitors the movement position in the wavelength tunable drive unit 3 and is supplied from the LD drive unit 8 to the wavelength tunable light source unit 2. Since the current is corrected and controlled according to the wavelength, the processing load on the CPU is increased, and there is a problem that mounting the CPU increases the cost of the wavelength tunable light source device.
[0013]
An object of the present invention has been made in view of the above problems, and a wavelength tunable light source device that realizes a function of controlling the output level of emitted light uniformly according to a variable wavelength without using a CPU at a low cost. The purpose is to provide.
[0014]
[Means for Solving the Problems]
The wavelength tunable light source device according to the first aspect of the present invention includes a semiconductor laser light source unit, an external resonance unit that externally resonates light emitted from the semiconductor laser light source unit at a predetermined wavelength, and external resonance conditions in the external resonance unit. A variable drive unit that outputs a position signal, a control unit that controls an external resonance condition in the drive unit, a light detection unit that detects a light output level of light emitted from the semiconductor laser light source unit, and the light detection A light source drive control unit that corrects a drive signal supplied to the semiconductor laser light source unit based on a light output level detected by the unit and controls the light output level to be constant; parts, the outputs a control signal for controlling the external resonance condition, a storage unit for storing a wavelength correction value corresponding to the wavelength of the light emitted from the semiconductor laser light source unit, the output from the drive unit A counting unit for counting an address to read the wavelength correction values stored in the storage unit based on the position signal, the provided, the light source drive control unit, read from the storage unit by an address which is counted in the counting section The optical output level is controlled to be constant by correcting the drive signal supplied to the semiconductor laser light source unit based on the wavelength correction value.
[0015]
Therefore, it is possible to realize a control function for controlling the output level of the emitted light constantly according to the variable wavelength by using a counter and a memory such as a ROM without using a CPU.
[0016]
In this case, the object is, for example, as in the invention described in claim 2, in the wavelength tunable light source device according to claim 1, the counting unit uses the bit string of a predetermined number of bits based on the position signal as the address. It is effective to control the addressing and reading timing of the wavelength correction value in the storage unit by dividing the counted bit string for addressing and reading timing and outputting to the storage unit. is there.
[0017]
Therefore, among the bit strings counted by the counter, for example, if the lower bit string is used for reading timing and the upper bit string is used for addressing, the wavelength correction value can be reliably read from the storage unit, and the output level of the emitted light can be set. It is possible to improve the reliability of the control function that performs constant control.
[0018]
Variable wavelength light source apparatus according to the third aspect, a semiconductor laser light source unit, and an external resonator unit for external resonator at a predetermined wavelength light emitted from the semiconductor laser light source unit, and a variable external resonance condition in the external cavity portion A drive unit that outputs an analog position signal indicating a position, a control unit that controls an external resonance condition in the drive unit, a light detection unit that detects a light output level of light emitted from the semiconductor laser light source unit, and In a variable wavelength light source device comprising: a light source drive control unit that corrects a drive signal supplied to the semiconductor laser light source unit based on a light output level detected by a light detection unit and controls the light output level to be constant. The control unit outputs an analog control signal for controlling the external resonance condition, and stores a wavelength correction value corresponding to the wavelength of the emitted light from the semiconductor laser light source unit; An address generator for generating an address for reading the wavelength correction values stored in the storage unit of the analog position signal output from the drive unit to digital conversion, the provided, the light source drive control unit, the address generator The optical output level is controlled to be constant by correcting the drive signal supplied to the semiconductor laser light source unit based on the wavelength correction value read out from the storage unit by the address generated in step.
[0019]
Therefore, it is possible to realize a control function for controlling the output level of the emitted light constantly according to the variable wavelength by using an A / D converter and a memory such as a ROM without using a CPU.
[0020]
According to a fourth aspect of the present invention, in the wavelength tunable light source device according to the third aspect, the address generation unit digitally converts the analog position signal to generate the address using a bit string having a predetermined number of bits. It is effective to control the addressing and reading timing of the wavelength correction value in the storage unit by dividing the generated bit string for the addressing and the reading timing and outputting them to the storage unit.
[0021]
Therefore, among the bit strings generated by the A / D converter, for example, if the lower bit string is used for read timing and the upper bit string is used for addressing, the wavelength correction value can be reliably read from the storage unit, and the emitted light The reliability of the control function for controlling the output level to be constant can be improved.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1 to 3 are diagrams showing an embodiment of a wavelength tunable light source device to which the present invention is applied.
First, the configuration will be described.
FIG. 1 is a block diagram showing a configuration of a wavelength tunable light source device 20 in the present embodiment. In FIG. 1, a wavelength tunable light source device 20 includes a wavelength tunable light source unit 21, a wavelength tunable drive unit 22, a drive control unit 23, a control unit 24, a counter 25, a ROM 26, a D / A converter 27, an LD drive unit 28, and light. The detection unit 29 is configured.
[0023]
The wavelength variable light source unit (TLS) 21 uses an external resonator type LD (not shown), and the optical position of the optical filter (not shown) constituting the external resonator is the wavelength variable drive unit 22. Therefore, the external resonance condition is varied, and the wavelength of the emitted light can be varied over a wide range (minimum wavelength λ0 to maximum wavelength λMAX). The light emitted from the wavelength tunable light source unit 21 is emitted as output light to the outside through the branched optical fiber 30 and is emitted to the light detection unit 28 as reference light.
[0024]
In addition, optical connection terminals 31 and 32 for sweeping the output light and the reference light to the external optical device and the light detection unit 28 are integrally attached to each output end of the branched optical fiber 30, The optical connection terminal 32 is connected to the light detection unit 29.
[0025]
The wavelength tunable drive unit 22 is composed of a pulse motor or the like, and the mechanical position of the optical filter in the wavelength tunable light source unit 21 by rotating and moving the pulse motor in accordance with a drive control signal input from the drive control unit 23. And a rotary encode signal indicating the movement position of the pulse motor is output to the drive control unit 23 as a position signal (digital signal).
[0026]
The drive control unit 23 generates a drive control signal according to the wavelength variable control signal input from the control unit 24 and outputs the drive control signal to the wavelength variable drive unit 22 to rotate and move the pulse motor, and is input from the wavelength variable drive unit 22. Position signal (rotary encode signal) is output to the control unit 24 and the counter 25.
[0027]
The control unit 24 has a control function for controlling the relationship between the movement position of the optical filter in the wavelength tunable light source unit 22 and the wavelength λ of the emitted light, and a wavelength variable control signal that sets the movement position corresponding to the wavelength λ. Is output to the drive control unit 23 to set the wavelength λ of the emitted light, and based on the position signal (rotary encode signal) input from the drive control unit 23, it is confirmed that the emitted light has the set wavelength λ. Thus, the drive control in the drive control unit 23 is stopped.
[0028]
The counter 25 counts the address in the correction wavelength table in which the correction wavelength data in the ROM 26 is stored based on the position signal (rotary encode signal) input from the drive control unit 23, and outputs the counted address to the ROM 26. Then, wavelength correction data corresponding to the wavelength is output from the correction wavelength table.
[0029]
The ROM 26 stores a wavelength correction table in which a plurality of wavelength correction data (digital data) for correcting the output level of the emitted light in the wavelength tunable light source unit 2 corresponding to the address input from the counter 25 is set.
[0030]
That is, the count operation in the counter 25 is a process of converting the position signal (rotary encode signal) input from the drive control unit 23 into the storage address of the wavelength correction value data stored in the wavelength correction table in the ROM 26. It becomes possible to output the wavelength correction value without using the CPU 6 as in the prior art.
[0031]
The D / A converter 27 performs D / A conversion on the wavelength correction value data input from the ROM 26 and outputs it to the LD driving unit 28 as a predetermined wavelength correction value.
[0032]
The LD drive unit 28 supplies a drive current to the LD in the wavelength tunable light source unit 21 based on the light detection signal input from the light detection unit 29 to control the output level of the emitted light to a constant level. In accordance with the wavelength correction value input from the converter 27, the drive current is corrected so as to correct the light detection characteristic corresponding to the wavelength in the light detection unit 29, for example, the amplification factor for amplifying the drive current is corrected, and the wavelength is corrected. Even if the wavelength of the light emitted from the variable light source unit 21 is varied, the output level is controlled to be constant.
[0033]
The light detection unit 29 includes a lens 29a and a light detection element 29b. The lens 29a emits the reference light input from the wavelength variable light source unit 21 through the optical fiber 30 through the optical connection terminal 12 as parallel light. The light is emitted to the detection element 29b. The light detection element 29b receives incident light from the lens 29a, converts it into a light detection signal of a predetermined voltage level according to the light intensity received with the light reception sensitivity characteristic according to the wavelength, and converts the light from the detection terminal 33 to the cable. The output is output to the LD drive unit 28 via 44.
[0034]
Next, the operation of the present embodiment will be described.
In the wavelength tunable light source device 20 of FIG. 1, first, when a wavelength variable control signal is output to the drive control unit 23 so as to have the initial wavelength λ0 by the control unit 24, the drive control signal is output from the drive control unit 23 to the wavelength variable drive. The rotation movement to the initial position of the pulse motor in the wavelength variable drive unit 22 is started. At this time, in the wavelength variable light source unit 21, the mechanical position of the optical filter constituting the external resonator is moved to the initial position by the wavelength variable drive unit 22, so that the external resonance condition is set to the initial state, When a predetermined drive current is supplied from the LD drive unit 28 to the LD, light having an initial wavelength λ 0 based on the initial external resonance condition is emitted to the outside as output light from the optical fiber 30, and the light detection unit 29 is emitted as reference light.
[0035]
Then, the control unit 24 confirms that the emitted light has the initial wavelength λ0 based on the position signal (rotary encode signal) input from the drive control unit 23, and stops the drive control in the drive control unit 23. . Next, when the control unit 24 outputs a wavelength variable control signal to the drive control unit 23 so that the initial wavelength λ 0 becomes an arbitrary variable wavelength λ 1, the drive control unit 23 outputs the drive control signal to the wavelength variable drive unit 22. Then, the rotational movement of the pulse motor in the wavelength tunable drive unit 22 to the set position corresponding to the wavelength λ1 is started.
[0036]
At this time, in the wavelength tunable light source unit 21, the mechanical position of the optical filter constituting the external resonator is moved from the initial position to the set position corresponding to the wavelength .lambda. When the condition is set to the wavelength λ1 state and a predetermined drive current is supplied from the LD drive unit 28 to the LD, the light of wavelength λ1 based on the external resonance condition of the wavelength λ1 is output to the outside through the optical fiber 30. And is output to the light detection unit 29 as reference light.
[0037]
When the emitted light is set to the wavelength λ1, the operation of correcting the drive current supplied from the LD drive unit 28 to the wavelength variable light source unit 21 is corrected by the drive control unit 23, counter 25, ROM 26, A description will be given based on the flow of each part signal between the blocks of the D / A converter 27 and the LD driving part 28.
[0038]
When the pulse motor is moved so that the wavelength of the emitted light is set to λ 1 in the variable wavelength drive unit 22, a rotary encode signal corresponding to the movement amount is fed back to the drive control unit 23. From the drive control unit 23, a position signal in the form of a signal as shown in FIG. 2 corresponding to the input rotary encode signal is output to the counter 25. The counter 25 counts an 8-bit address as shown in FIG. 2 according to the number of pulses set in the position signal input from the drive control unit 23 and outputs it to the ROM 26.
[0039]
Of the 8-bit address counted by the counter 25, the lower 4 bits are used for addressing timing in the ROM 26 and D / A conversion timing in the D / A converter 27, and the upper 4 bits are used. This is used to specify the storage address of the wavelength correction data stored in the wavelength correction table in the ROM 26.
[0040]
Therefore, a position signal indicating the movement position of the pulse motor (corresponding to the movement position of the optical filter) in the wavelength tunable drive unit 22, the address counted by the counter 25, and the wavelength correction data stored in the wavelength correction table in the ROM 26. The correspondence relationship between and is measured and set in advance.
[0041]
In the ROM 26, when the storage address in the wavelength correction table indicated by the upper 4 bits is designated at the input timing of the lower 4 bits of the address input from the counter 25, the same is made for every lower 4 bits. Since the storage address is repeatedly specified, the storage address is surely specified. When the wavelength correction data corresponding to the current wavelength λ1 is read from the designated address in the wavelength correction table from the ROM 26 and output to the D / A converter 27, the D / A converter 27 receives the data from the counter 25. The D / A conversion processing of the wavelength correction data is performed at the input timing for the lower 4 bits of the address to be output to the LD driving unit 28 as the wavelength correction value corresponding to the wavelength λ1.
[0042]
Next, in the LD drive unit 28, the drive current is corrected so as to correct the light detection characteristic corresponding to the wavelength λ 1 in the light detection unit 29 according to the wavelength correction value corresponding to the wavelength λ 1 input from the D / A converter 27. The amplification factor for amplifying the drive current is corrected, and the output level of the light of wavelength λ1 emitted from the wavelength variable light source unit 21 is controlled to be constant.
[0043]
Further, even when the wavelength λ of the emitted light from the wavelength tunable light source unit 21 is changed to another arbitrary wavelength λn within the variable range (minimum wavelength λ0 to maximum wavelength λMAX), the position signal from the counter 25 is similarly obtained. Is output to the ROM 26, and wavelength correction data corresponding to the wavelength λn is output from the ROM 26 to the D / A converter 27. In the LD drive unit 28, the drive current is corrected so as to correct the light detection characteristic corresponding to the wavelength λn in the light detection unit 29 according to the wavelength correction value corresponding to the wavelength λn input from the D / A converter 27, The amplification factor for amplifying the drive current is corrected, and the output level of the light of wavelength λn emitted from the wavelength variable light source unit 21 is controlled to be constant.
[0044]
As described above, in the wavelength tunable light source device 20 according to the present embodiment, the address designation of the wavelength correction data stored in the wavelength correction table in the ROM 26 in advance is used as the moving position signal of the pulse motor in the wavelength tunable drive unit 22. Correspondingly, since the counter 25 that counts the storage address is used, it is unnecessary to read out the wavelength correction value from the ROM 7 by the CPU 6 as in the conventional wavelength tunable light source device 1 shown in FIG. The CPU 6 can be dispensed with.
[0045]
Therefore, in the wavelength tunable light source device, it is possible to realize a control function for controlling the output level of the emitted light uniformly according to the variable wavelength without using a CPU.
[0046]
In the above embodiment, the case where the position signal output from the drive control unit 23 to the counter 25 is a digital signal is shown. However, the configuration of the main part of the control system when the position signal is an analog signal is shown in FIG. 3 shows the wavelength tunable light source device 40.
[0047]
In the wavelength tunable light source device 40 shown in FIG. 4, the position signal output from the drive control unit 41 is an analog position signal, and the portion where the A / D converter 42 is used in place of the counter 25 is the above. It is a different part from the wavelength tunable light source device 20 shown in the embodiment, and includes a ROM 26, a D / A converter 27 and an LD drive unit 28, a wavelength variable light source unit 21, a wavelength tunable drive unit 22, and a light detection unit 29 (not shown). It is the same configuration.
[0048]
In this case, when an analog position signal is input from the drive control unit 41 to the A / D converter 42, it is A / D converted into an 8-bit address similar to the data format shown in FIG. 2 shown in FIG. In the same manner as in the above embodiment, the storage address of the wavelength correction data stored in the wavelength correction table in the ROM 26 is designated at the input timing for the upper 4 bits of the address, and the variable wavelength light source unit 21 is output. The wavelength correction data corresponding to the wavelength λ of the light being emitted from is output to the D / A converter 27.
[0049]
In the D / A converter 27, the D / A conversion processing of the wavelength correction data is performed at the input timing of the lower 4 bits of the address input from the A / D converter 42, and the wavelength correction corresponding to the wavelength λ is performed. A value is output to the LD drive unit 28. In the LD drive unit 28, the drive current is corrected so as to correct the photodetection characteristics corresponding to the wavelength λ1 in the photodetection unit 29 according to the wavelength correction value corresponding to the wavelength λ input from the D / A converter 27. The amplification factor for amplifying the drive current is corrected, and the output level of the light having the wavelength λ emitted from the wavelength tunable light source unit 21 is controlled to be constant.
[0050]
Therefore, in this wavelength tunable light source device 40, it is possible to realize a control function for controlling the output level of the emitted light uniformly according to the variable wavelength without using a CPU.
[0051]
【The invention's effect】
According to the wavelength tunable light source device of the first aspect of the invention, the control function for controlling the output level of the emitted light to be constant according to the variable wavelength by using a counter and a memory such as a ROM without using a CPU. It can be realized at low cost.
[0052]
According to the wavelength tunable light source device of the second aspect, among the bit strings counted by the counter, for example, if the lower bit string is for reading timing and the upper bit string is for addressing, the wavelength correction value is obtained from the storage unit. It is possible to reliably read out, and it is possible to improve the reliability of the control function for controlling the output level of the emitted light to be constant.
[0053]
According to the wavelength tunable light source device of the present invention, the output level of the emitted light is controlled to be constant according to the variable wavelength by using an A / D converter and a memory such as a ROM without using a CPU. The control function can be realized at low cost.
[0054]
According to the wavelength tunable light source device of the invention described in claim 4, if, for example, the lower bit string is used for read timing and the upper bit string is used for addressing among the bit strings generated by the A / D converter, the wavelength from the storage unit The correction value can be read out reliably, and the reliability of the control function for controlling the output level of the emitted light to be constant can be improved.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a control system inside a wavelength tunable light source device 20 according to an embodiment to which the present invention is applied.
2 is a diagram showing the flow of signals of each part among blocks of a drive control unit 23, a counter 25, a ROM 26, a D / A converter 27, and an LD drive unit 28 in FIG. 1;
FIG. 3 is a block diagram illustrating a configuration of a main part of a control system inside a wavelength tunable light source device 40 according to another embodiment to which the present invention is applied.
FIG. 4 is a block diagram showing a configuration of a control system inside a conventional variable wavelength light source device 1;
[Explanation of symbols]
20, 40 Variable wavelength light source device 21 Variable wavelength light source unit 22 Variable wavelength drive unit 23, 41 Drive control unit 24 Control unit 25 Counter 26 ROM
27 D / A converter 28 LD drive unit 29 Photodetection unit 29a Lens 29b Photodetection element 30 Optical fibers 31, 32 Optical connection terminal 33 Detection terminal 42 A / D converter

Claims (4)

A semiconductor laser light source unit;
An external resonating unit for externally resonating light emitted from the semiconductor laser light source unit at a predetermined wavelength;
A drive unit that varies external resonance conditions in the external resonance unit and outputs a position signal indicating the position ;
A control unit for controlling external resonance conditions in the drive unit;
A light detection unit for detecting a light output level of light emitted from the semiconductor laser light source unit;
A light source drive control unit for correcting a drive signal supplied to the semiconductor laser light source unit based on a light output level detected by the light detection unit and controlling the light output level to be constant;
In a wavelength tunable light source device comprising:
The control unit outputs a control signal for controlling the external resonance condition;
A storage unit for storing a wavelength correction value corresponding to the wavelength of light emitted from the semiconductor laser light source unit;
A counting unit that counts an address for reading a wavelength correction value stored in the storage unit based on a position signal output from the driving unit ;
The light source drive control unit corrects a drive signal supplied to the semiconductor laser light source unit based on a wavelength correction value read from the storage unit by an address counted by the counting unit, and controls a light output level to be constant. A tunable light source device characterized in that: The counting unit counts the address with a bit string having a predetermined number of bits based on the control signal, and classifies the counted bit string for the address designation and for the read timing and outputs it to the storage unit. 2. The wavelength tunable light source device according to claim 1, wherein addressing and reading timing of the wavelength correction value in the storage unit are controlled. A semiconductor laser light source unit;
An external resonating unit for externally resonating light emitted from the semiconductor laser light source unit at a predetermined wavelength;
A drive unit for changing an external resonance condition in the external resonance unit and outputting an analog position signal indicating a position ;
A control unit for controlling external resonance conditions in the drive unit;
A light detection unit for detecting a light output level of light emitted from the semiconductor laser light source unit;
A light source drive control unit for correcting a drive signal supplied to the semiconductor laser light source unit based on a light output level detected by the light detection unit and controlling the light output level to be constant;
In a wavelength tunable light source device comprising:
The drive unit outputs an analog control signal for controlling the external resonance condition;
A storage unit for storing a wavelength correction value corresponding to the wavelength of light emitted from the semiconductor laser light source unit;
An address generation unit that converts an analog position signal output from the drive unit into a digital signal and generates an address for reading a wavelength correction value stored in the storage unit; and
The light source drive control unit corrects a drive signal supplied to the semiconductor laser light source unit based on a wavelength correction value read from the storage unit based on an address generated by the address generation unit, and makes a light output level constant. A wavelength tunable light source device characterized by controlling. The address generation unit digitally converts the analog control signal to generate the address with a bit string of a predetermined number of bits, and outputs the generated bit string for the address designation and the read timing to the storage unit 4. The wavelength tunable light source device according to claim 3, wherein addressing and reading timing of the wavelength correction value in the storage unit are controlled.

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