JPH05198885A - Laser wavelength control equipment of ld module - Google Patents

Abstract

PURPOSE:To easily prevent it without complication that the oscillation center wavelength of an LD fluctuates on account of temperature fluctuation. CONSTITUTION:The light output of an LD 11 of an LD module 1 in which a Peltier cooler 12 is contained for cooling is made to pass an optical narrow band filter 2 which passes only the wavelenth to be set, and inputted in a PD 3. The output of the PD 3 is inputted in a temperature adjusting circuit 4 which controls the Peltier cooler 12. The temperature adjusting circuit 4 controls the Peltier cooler 12 so as to make the light entering the PD 3 maximum, and sets the temperature. Thereby the light whose wavelength is set can always automatically obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser wavelength controller for an LD module, and more particularly to a laser wavelength controller for an LD module by temperature control.

[0002]

2. Description of the Related Art A conventional LD module laser wavelength control device, as shown in FIG. 3, uses a signal from a thermistor 9 in order to keep the oscillation wavelength of an LD (laser diode) 8 of an LD module 6 constant. Peltier cooler for cooling 1
0 is controlled to keep the temperature constant.

That is, when the temperature rises due to the heat generation of the LD 8, the resistance value of the thermistor 9 changes, and the voltage is input to the comparator 7. In the comparator 7, REF (reference voltage)
If the voltage of the thermistor 9 is different from that of the thermistor 9, a current flows through the Peltier cooler 10 to cool the LD 8 and the thermistor 9 and feedback is applied so that the voltage becomes the same as REF of the comparator 7. In this way, the LD8 temperature is prevented from rising excessively, and the LD
This prevents large fluctuations in the oscillation wavelength of 8.

[0004]

By the way, in the conventional laser wavelength control device for the LD module, the REF voltage of the comparator 7 is calculated and tested so as to obtain an appropriate temperature in order to obtain the desired wavelength. There was a problem that it was complicated by that. That is,
When the output power of the LD 8 changes, the amount of heat generated by the LD 8 also changes, and the heat radiation conditions also change depending on the shape and mounting method of the LD module. Moreover, each LD8
Since the oscillation wavelength differs depending on the temperature, there is a problem that the actual adjustment is performed by an experiment. Also,
There was also a problem that the thermistor was not very reliable.

The present invention has been made in view of the above problems, and provides a laser wavelength control device for an LD module that can easily prevent fluctuations in the oscillation center wavelength of the LD without complicating. To aim.

[0006]

In order to achieve the above object, a laser wavelength control device for an LD module of the present invention comprises an LD
In a laser wavelength control device for an LD module that cools the LD of the module with a cooling Peltier cooler to control the laser wavelength, an optical narrow band filter that allows only a predetermined wavelength of the output of the LD module to pass, and an optical narrow band filter The PD is configured to photoelectrically convert the output, and the temperature adjusting circuit that controls the cooling Peltier cooler so that the maximum output wavelength of the LD becomes the predetermined wavelength based on the output of the PD.

[0007]

According to the laser wavelength control device of the LD module having the above structure, the output of the LD module with the built-in cooling Peltier cooler passes through the optical narrow band filter only for a certain wavelength, and the optical signal passes through the optical narrow band filter. Is monitored by the PD, and the Peltier cooler for cooling is controlled by the temperature adjustment circuit which receives the signal from the PD, and the temperature of the LD module is automatically adjusted.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a laser wavelength control device for an LD module according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes an LD module, which comprises an LD (laser diode) 11 and a cooling Peltier cooler 12 for cooling the LD 11. 2 is L
It is an optical narrow band filter that passes only a predetermined wavelength λ of the output of D11. Reference numeral 3 is a PD (photodiode) that photoelectrically converts the output of the optical narrow band filter 2.

Reference numeral 4 denotes a temperature adjusting circuit, which is PD3
The cooling Peltier cooler 12 is controlled so that the maximum output wavelength of the LD 11 becomes the predetermined wavelength λ based on the output of the above. Reference numeral 5 is a bias supply circuit for causing the LD 11 to output light.

Therefore, the laser wavelength control device for the LD module according to this embodiment operates as follows. When the current flowing through the LD 11 of the LD module 1 increases, the amount of heat generated increases and the temperature of the LD 11 rises.
When the oscillation center wavelength λ of the LD 11 rises in temperature, it shifts to λ ′ (long wavelength side) as shown in FIG.

The output of the LD module 1 passes through the optical narrow band filter 2 which passes only the wavelength λ desired to be set, and the output of the PD 3
To enter. The PD 3 converts the light of wavelength λ into electricity and inputs it to the temperature adjustment circuit 4.

Although the optical power of the wavelength that passes through the narrow band filter 2 at high temperature is lower than that at low temperature, the temperature adjusting circuit 4 controls the Peltier cooler 12 built in the LD module 1. However, the LD is shifted so that the light input to the PD 3 is maximized, that is, the LD is shifted by the temperature rise.
The oscillation center wavelength λ ′ of 11 is fed back so as to be returned to λ by cooling. The optical output power of the LD 11 changes with the bias current from the bias supply circuit 5.

[0014]

As described above, according to the laser wavelength controller for the LD module of the present invention, the temperature is automatically controlled by the Peltier cooler so as to maximize the light passing through the optical narrow band filter. , LD oscillation center wavelength can be set and adjusted without adjustment by selecting a narrow band filter. Further, since no thermistor is used, it is also advantageous in terms of reliability.

[Brief description of drawings]

FIG. 1 is a block diagram showing a laser wavelength control device for an LD module according to an embodiment of the present invention.

FIG. 2 is a graph showing changes in the optical spectrum of an LD with temperature.

FIG. 3 is a block diagram showing a conventional laser wavelength control device for an LD module.

[Explanation of symbols]

 1 LD Module 2 Optical Narrow Band Filter 3 PD 4 Temperature Control Circuit 5 Bias Supply Circuit 6 LD Module 7 Comparator 8, 11 LD 9 Thermistor 10, 12 Peltier Cooler

Claims (1)

[Claims] 1. A laser wavelength control device for an LD module, wherein an LD of an LD module is cooled by a Peltier cooler for cooling to control a laser wavelength, and an optical narrow band filter that passes only a predetermined wavelength of the output of the LD module, PD for photoelectrically converting the output of the optical narrow band filter
And a temperature adjusting circuit for controlling the cooling Peltier cooler so that the maximum output wavelength of the LD becomes the predetermined wavelength based on the output of the PD.
Laser wavelength control method for modules.