Development Of A Control System For Ageing And Screening Laser Diodes

Semiconductor laser diodes have wide applications in many areas such as communication, military and medical treatment. The industrialization of laser diodes demands the aging and screening process to be controlled by high-automatic and high-intelligentized control system.To meet the demand, we develop an ageing and screening control system for the laser diode,which is high-automatic and convenient for mass production. In this paper, the control system for laser diode aging and screening is elaborated. At first, the concepts of ageing and reliability of laser diodes are discussed and the survey of development of laser diode reliability testing system in domestic and foreign is made. Then the principle of designing the system is presented.Based on the design principle, a systematic structure of adopting principal and subordinate control is brought forward. The upper one is a PC and the lower one is the control unit with a single chip core.PC communicates with single chip by RS-232 interface to realize the data and command transfer between them. The lower unit consists of one control board and 16 drive boards.Every drive board can drive a diode laser.The function of control unit single chip in the driver board is to control the aging process of 16 laser diodes in current mode or in output power mode. Combining the virtue of single chip in real time control and data collection with the virtue of PC in figure displaying and data processing, the control system has the characteristic of real-time, good expansibility, universality, also friend human-machine interface. During the development of control circuit on the driver board, the author puts forward a new structure of the circuit, which is simpler than the existing one and is able to work in the current mode or output power mode. And also, some methods are applied to protect the laser and enhance the anti-jamming ability of the system. The author develops a method in which a Matlab-based software is designed to validate the function of driver circuits and optimize the structure of the driver circuit. The mathematical model is established firstly according to the adjustable parameters in the circuits.Then Matlab-based softeware is designed to sample and simulate the circuits with the change of the adjustable parameters in the mathematical model.The results of the simulation are helpful to select the components especially the power triode and to guide the real design of the circuit so that the time and cost are saved greatly. The simulation plateform is introduced and an optimum design example is presented in the paper.