Design Of Low Temperature Drift Driver For FMCW Laser

The current-tuned semiconductor laser has compact structure,fast modulation speed,and is suitable for ranging dynamic objects.It has become an ideal light source for FMCW(Frequency Modulated Continuous Wave)ranging technology.However,due to its working characteristics and structural defects,it causes non-linear changes in frequency,which reduces the accuracy and resolution of measurement.Current-tuned semiconductor lasers are affected by environmental factors during the working process and are more sensitive to driving current and temperature changes.In this paper,by studying the semiconductor laser driving technology,in order to improve the stability of the output signal of the semiconductor laser and reduce the influence of temperature on the laser driving system,a low temperature drift driver for FMCW laser is designed.Based on the study of current drive and temperature control principles,this paper designs a low-temperature drift driver for FMCW lasers.After analyzing the working characteristics and principles of current-tuned semiconductor lasers,the conditions for high-precision measurement of lasers and the factors affecting their stability are summarized.The principle of constant current drive,constant temperature drive and low temperature drift technology is studied,and the design scheme of FMCW laser low temperature drift driver is proposed.The overall plan design includes the upper computer and the lower computer.The upper and lower computers use Ethernet port communication,which not only ensures the stable transmission of waveform data and control commands,but also facilitates the network calibration of multiple lasers.The upper computer is designed based on MATLAB to realize the functions of generating correction waveform data and sending control commands.The lower computer drivr board is designed with low temperature drift arbitrary waveform constant current source circuit,temperature compensation module and constant temperature drive module.Among them,the low-temperature drift arbitrary waveform constant current source circuit mainly includes a reference voltage circuit,a waveform generating circuit,an adjustable bias voltage superimposing circuit,a low-pass filter circuit and a constant current output circuit,which can output a specific nonlinear drive according to the waveform data sent by the host computer Current.The parallel structure of the field effect tube is used as the regulator tube of the constant current output circuit,and the low temperature drift precision resistance is selected as the sampling resistance to reduce the influence of temperature on the driving current.A temperature compensation module is designed for the constant current output circuit,and a new driving current is recalculated according to the established temperature compensation model through the collected temperature value to reduce the error caused by the temperature drift property.The temperature control chip is used to design the laser constant temperature drive circuit,which forms a closed-loop temperature feedback with the internal TEC module and thermistor of the laser to stably control the working temperature of the laser.Experimental results show that the laser low-temperature drift driver can output arbitrary waveforms preset by the host computer,and realize the function of continuously adjustable output current.The output driving current range is50?350m A,and the relative error is less than 0.05%;the working temperature of the laser is adjusted by controlling the TEC cooler,and the temperature fluctuation is less than 0.05?.The driver can effectively drive the laser to perform high-precision measurements to meet design requirements.