The Research And Design Of High-Power Semiconductor Laser Diode Controller

With the rapid development of science and technology, the techniques of semiconductor laser diode had been applied widely in many fields such as industry, high tech and science research. Semiconductor laser diode has the excellent character of high efficiency, small size, low weight, high reliability, direct modulation, but semiconductor laser diode is a kind of device with high power density and sky-high quantum efficiency. Even weak drive current and temperature change will lead to its large change of output light power and device parameters, which directly damages the safe use of laser diode. At the same time, semiconductor laser diode is very sensitive to the temperature. The fluctuation of surrounding temperature not only leads to the fluctuation of supply current, but also makes threshold current, quantum efficiency, output wavelength and output light intensity of the laser diode change greatly. So higher request to the laser diode controller is put forward. The control precision of traditional laser diode controller is very low, and the operation is difficult, and cannot shift between constant current mode and constant power mode. However, the laser diode controller designed in this paper overcomes these disadvantages above, and possesses vivid technical advantage.The controller of semiconductor laser diode includes tow parts: the part of driving and the part of constant temperature control. The part of driving includes constant current control, constant power control and pulse modulation control. This paper first analyzes a good many factors that affect the stability of semiconductor laser diode on the basis of principles of semiconductor laser diode. Then, it discusses in detail the significance and theoretic basis of designing this control system. And finally it summarizes the key technology in the design process from three aspects. This paper involves the knowledge of electronic theory, optical theory, thermoelectric cooling technology, and the theory of negative feedback control and PID control. The research achievements in this paper lie in: according to the character of high-power semiconductor laser diode, we have designed a kind of practical laser diode controller, and its partial technical indexes reach the level of the same kind of product. Among controller, the short-term stability of the controller whose drive current is 200 mA is 10ppm, and its long-term stability is 38ppm. Both of them exceed the product of overseas companies. The controller has these advantages as followed: delaying and soft-start circuit avoids the laser diode being frustrated by the impulse during the power-on; the limit current is independently set; the user can adjust and set the limit current and operating current in convenience; constant current and constant power drive modes; the sensitivity of PD is selective; the controller can be modulated by external signal. Temperature control precision of this constant temperature controller is 0.1℃; its short term stability is 0.02℃;its long term stability is 0.05℃. This paper illustrates the question of EMC and PCB board during the process of controller design, and provides a rational method. Finally, it also explains the application example of both controller and the LD whose model is HPD1203-HHLF-TEC-FAC, and discusses the question at present and the developing direction in the futureThis work mentioned in the paper has positive significance to the wide application of semiconductor laser diode, which solves key questions in the application of semiconductor laser diode. The practical application indicates that the controller has the following advantages: strong anti-interference ability, high stability and no damages to laser diodes.