Development Of Tunable Fiber Laser Frequency Locking Control Circuit Based On FPG

PDH(Pound-Drever-Hall)frequency stabilization technology is an important means to realize the frequency locking of tunable laser.In the current experiments of optical fiber sensing and optical fiber communication,most of the frequency locking of tunable lasers is accomplished by large analog circuits,which were easily affected by the noise interference of the circuits themselves.In this paper,based on the principle of PDH frequency stabilization technology,a frequency locking control scheme based on FPGA is proposed,and the basic architecture of the frequency locking control system of the tunable fiber laser has been designed.The demodulation simulation model has been established by using Simulink,and The theory of frequency mixing filter demodulation was verified.In Quartus II,the design of A/D analog-to-digital conversion circuit driver module,D/A digital-to-analog conversion circuit driver module,DDS(Direct Digital Synthesizer)signal generator module,mixer module and low-pass filter module have been completed.And its function has been simulated and verified in Modesim.The PDH error signal detection experiment platform was built,and the PDH error signal detection experiment has been carried out using the resonance peak of π phase-shift grating equivalent to the resonance peak of high fineness FP(Fabry Perot)cavity as the frequency discrimination standard.Using the PZT(Piezoelectric ceramics)tunable fiber laser controlled by triangular wave voltage to perform wavelength scanning,PDH error curve has been obtained;Based on the experimental error curve,the frequency locking control of the tunable fiber laser can be realized by tuning the control voltage at the PZT terminal and then changing the resonant peak wavelength of the active phase-shifted fiber grating tuned by the voltage electroceramics.To sum up,the digital-to-analog conversion circuit with FPGA as the core,the signal generator circuit,the mixing circuit and the low-pass filter circuit can be effectively integrated into one,which lays a foundation for the integration of the frequency locking control circuit of the tunable fiber laser.