Design of Temperature Control System for Distributed Feedback Laser

Distributed feedback lasers are widely used in communication and gas concentration detection, but they are easily affected by ambient temperature. In order to solve the problem that the power and output wavelength stability of distributed feedback laser are affected by temperature fluctuation, a distributed feedback laser temperature control system is proposed, which mainly includes temperature measurement circuit, H-bridge drive circuit and semiconductor cooler drive circuit. In the temperature measurement circuit, the temperature is calculated by measuring the voltage at both ends of the thermistor through the ADC channel of the single chip computer. H-bridge drive circuit receives PWM wave from single-chip microcomputer and controls the 4 NMOS tubes of H-bridge. The semiconductor cooler drive circuit is composed of an H-bridge to change the direction of the current flowing through the semiconductor cooler. After testing, the temperature control range is 20 to 50℃, under the room temperature condition of 20.35℃, the target temperature is set at 30℃, and the temperature fluctuation is less than ±0.05℃ within half an hour of operation. The system has the advantages of low cost, high temperature control precision, strong stability and large temperature control range.