Research On The DFB Tunable Lasers Driving Technology Based On FPGA

In the rapid development of science and technology today,semiconductor lasers in scientific and technological research and industrial production and other aspects of the application more and more widely.DFB lasers have the characteristics of general semiconductor lasers just as small in size,highly integrated and themself have a function of modulating the output.However,semiconductor lasers are affected by environmental factors in work engineering,poor resistance to current shock,and output are more sensitive to changes in temperature and current.In order to stabilize the output of the semiconductor laser,the requirements for driving the power supply of the semiconductor laser are more stringent and research on its driving technology continues to develop.In the background of the LFMCW laser measuring system,the DFB tunable laser-related drive system for the measurement system is designed based on FPGA in this paper.The design of the DFB semiconductor laser tuning dr ive system in this paper mainly includes two parts: the part of current-driving and the part of temperature-controling.Firstly,this paper analyze the principle of the lasers and the factors that affect the stability of the lasers.The basic requirements of the design of the laser driver are put forward,and the basic constant current and temperature working principle of the lasers are analyzed.In this paper,a practical digital-mode combined lasers current drive system is designed according to the characteristics of DFB semiconductor lasers,using the basic temperature-current control analog circuit and the digital closed-loop control of the system based on FPGA to improve the stability of the driving system.In the current drive process,the FPGA drive DA and DDS output voltage signal,and the output can be tuned stable current signal after the addition of the circuit as a constant current source input-voltage.In the constant current control part,the use of dual-control: current negative feedback and digital PID,achieve the purpose of controlling the stability of the output current.And finally make the constant current output current stability to achieve the design requirements of 0.05%.In the thermostat control system,the design mainly control PWM driver output current to control TEC through the temperature-control chip MAX1978 peripherals analog PID closed-loop circuit.At the same time,the external flexible digital PID further control,so that to make the temperature stability to achieve the design requirements that is less than 0.01 ?.According to the final system verification,the design of FPGA-based DFB tunable laser drive and system have a good current and temperature stability System protection circuit can effectively protect the safety of semiconductor lasers,making the drive system work more stable?...