Design And Implementation Of A Pulsewidth-tunable Driver Circuit For Semiconductor Laser

In recent years,pulsed laser technology has developed rapidly and is widely used in medical,optical communication,laser processing and other fields.Semiconductor pulsed lasers based on gain-switching technology generate optical pulses of different frequencies and pulse widths to meet a variety of different application requirements.Since the output characteristics of semiconductor pulsed lasers are greatly influenced by the electrical pulse of the driving source,it is important to generate precise and stable electrical pulses with narrower pulse widths in order to optimize the laser output.With these objectives in mind,this paper research on the pulse drive circuit of the semiconductor laser and design a drive circuit with adjustable pulse width and frequency.The main contents of this paper are as follows:(1)A narrow pulse with adjustable pulse width is generated using a relative delay technique,and a high-bandwidth amplifier is used to amplify the amplitude of the narrow pulse so that it is sufficient to drive a semiconductor laser.The narrow pulse generation circuit mainly consists of a delay circuit,a pulse synthesis circuit and an amplifier circuit,the FPGA is used as an external control module to control the delay time of the delay circuit,which in turn realizes the function of adjustable pulse width of the output narrow pulse.Finally,the narrow pulse width is adjustable in the range of150 ps-10 ns,the pulse width resolution is 10 ps,and the pulse amplitude is 1V-2V.(2)A square wave signal circuit with adjustable output frequency is designed using direct digital frequency synthesis technology as the trigger signal for the narrow pulse generation circuit.The square wave signal with 0-50 MHz can be generated by the control of FPGA,which enables the adjustment of the output frequency of the narrow pulse generation circuit.(3)Using the circuit designed in this paper to drive the semiconductor laser,the response of the laser output light pulse to the electric pulse is tested,and the pulse width and frequency of the light pulse are adjusted.By adjusting the pulse width of the electric pulse,it is possible to make the laser output a spike pulse with a short pulse width,which verifies the feasibility of the circuit.