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Design method of a PD-based temperature control system for laser diode

Semiconductor lasers are widely used as pump and probe laser light source in atomic physics and quantum science equipment researches. The characteristics of the laser diodes,such as threshold current,wavelength,output power,lifetime,are temperature dependent,therefore it is vitally important to control the temperature of semiconductor lasers. Based on the relation between laser temperature and the output power,a photodiode( PD) based laser temperature control system was proposed. The light power of lasers can be acquired by the monitor photodiode in the laser package and then the laser junction temperature can be obtained by the relation between the power and the temperature. A double close loop control system was designed using the photodiode integrated with the temperature sensor and the thermoelectric coolers as the actuator. The test result indicates that the long-term stability of the photodiode-baserd laser diode temperature control system can realize better than ± 5 m K and meet the requirement of semiconductor lasers for the experiment and study of atomic physics.