JPH03283585A - Light oscillator - Google Patents

Abstract

PURPOSE:To avoid an unstable operation without forcible high temperature operation temporarily at a semiconductor laser by controlling an electronic cooler based on the detected result of a variation amount in the forward DC voltage drop of the laser. CONSTITUTION:A modulator 15 applies a modulating pulse current to a semiconductor laser 1. Simultaneously, a light output stabilizer 16 controls the DC bias of the laser 1 in response to variation in the photocurrent of a photodiode 5, and holds the average value of the output optical power of the laser 1 constant. Further, a temperature controller 17 has a circuit for detecting variation in the forward DC voltage drop of the laser 1, regulates a DC current value flowing to an electronic cooler 6 by corresponding the detected variation amount to variation in the temperature of the laser 1, and holds the temperature of the laser 1 constant. The follow-up of the temperature controller for cooling the laser 1 is enhanced to avoid a disadvantage in which the operation becomes unstable due to the temperature rise of the laser 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical oscillation device used in a transmitter for optical fiber communication, and particularly to a cooled optical oscillation device having a wide operating temperature range.

[Conventional technology]

Conventionally, as shown in FIG. 3, a semiconductor laser module in this type of optical oscillation device has an optical system that condenses the emitted light from the semiconductor laser 1 using a lens 2 and couples it to an optical fiber 3, and a semiconductor laser module that uses the semiconductor laser 1. It is composed of a thermistor 4 that detects temperature by replacing it with a change in resistance value, and an electronic cooling element 6 that uses the Peltier effect to cool the semiconductor laser 1. The photodiode 5 is provided to convert the rear output light of the semiconductor laser 1 into a current and monitor the output of the semiconductor laser 1 (Reference: Nakayo et al. "FiLD module in a cooling element with excellent frequency response", 1982). IEICE National Conference C-450, P.1-15
5.1988.3).

[Problem to be solved by the invention]

In the conventional optical oscillation device described above, the thermistor 4 that detects temperature within the semiconductor laser module and the semiconductor laser 1 are installed at a separate position, so the time constant required for heat conduction between the two is large. Therefore, even if a feedback circuit is provided to detect a change in the resistance value of the thermistor 4 and change the drive current of the thermoelectric cooling element 6, if the thermal time constant is large, it will not be able to follow sudden temperature changes, and the semiconductor There was a drawback that the temperature of the laser 1 rose and the operation became unstable.

[Means for solving the lI problem]

The optical oscillation device of the present invention includes a semiconductor laser, an optical system for coupling emitted light from the semiconductor laser to an optical fiber,
In an optical oscillation device equipped with a semiconductor laser module including an electronic cooling element for cooling the semiconductor laser, a detection means for detecting the amount of change in forward DC voltage drop of the semiconductor laser, and a detection means for detecting the amount of change in the forward DC voltage drop of the semiconductor laser. and control means for controlling the electronic cooling element based on the result.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG. 2 is a block diagram of an embodiment of the present invention.
It is a front view of the semiconductor laser module 10 in a figure.

As shown in FIG. 2, the light emitted from the semiconductor laser 1 of the semiconductor laser module 10 is focused by a lens 2 and coupled to an optical fiber 3. As shown in FIG. An electronic cooling element 6 and a lens 2 for cooling the semiconductor laser 1 are attached to a substrate to which the semiconductor laser 1 is fixed. The forward terminal voltage of the semiconductor laser 1 tends to decrease as the temperature increases. By utilizing this characteristic, the temperature change can be determined by the amount of change in the terminal voltage of the semiconductor laser 1.

Referring to FIG. 1, the semiconductor laser module 10 includes terminals 11 and 12 of the semiconductor laser 1, a photodiode 5 for monitoring, and terminals 13 and 14 of the photodiode 5.
This is the provision. The optical fiber 3 takes out the output light of the semiconductor laser module 10. The modulation circuit 15 applies a modulation pulse current to the semiconductor laser 1. At the same time, the optical output stabilization circuit 16 controls the DC bias current of the semiconductor laser l according to the photocurrent chamber of the photodiode 5,
The average value of the output optical power of the semiconductor laser 1 is kept constant.

Furthermore, the temperature control circuit 17 is a circuit (for example, an integrating circuit) that detects a change in the forward DC voltage drop of the semiconductor laser 1.
The detected amount of change corresponds to the amount of temperature change of the semiconductor laser 1, and the value of the DC current flowing through the electronic cooling element 6 is adjusted to keep the temperature of the semiconductor laser 1 constant.

〔Effect of the invention〕

As explained above, the optical oscillation device according to the present invention detects the temperature change of the semiconductor laser from the amount of change in the terminal voltage of the semiconductor laser itself, so that it is possible to quickly and accurately detect the temperature. Therefore, the followability of the temperature control circuit for cooling the semiconductor laser is improved, and the semiconductor laser is not forced to operate at a high temperature temporarily. That is, there is an effect that unstable operation of the semiconductor laser can be avoided.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a front view of the semiconductor laser module 10 in FIG. 1,
FIG. 3 is a front view of a semiconductor laser module in an example of a conventional optical oscillation device. DESCRIPTION OF SYMBOLS 1... Semiconductor laser, 2... Lens, 3... Optical fiber, 4... Thermistor, 5... Photodiode, 6... Electronic cooling element, 10... Semiconductor laser module, 11 .12...Terminal of semiconductor laser, 13
．． 14... Terminal of photodiode 5, 15... Modulation circuit, 16... Optical output stabilization circuit, 17... Temperature control circuit.

Claims (1)

[Claims] An optical oscillation device comprising a semiconductor laser module including a semiconductor laser, an optical system for coupling emitted light from the semiconductor laser to an optical fiber, and an electronic cooling element for cooling the semiconductor laser. a detection means for detecting the amount of change in the forward DC voltage drop of the laser;
A light oscillation device comprising: a control means for controlling the electronic cooling element based on a detection result of the detection means.