Design of seed laser injection locking system for 2μm solid-state laser based on FPGA

The excellent properties of the narrow linewidth, single longitudinal mode and constant frequency of the seed-injected solid-state single-frequency pulse laser make it suitable in the applications of the gravitational wave detection, doppler wind radar, and greenhouse gas flux measurement. FPGAs have been widely utilized in the laser electronic control systems due to its high integration and parallel processing capabilities. Based on the classical Ramp-Hold-Fire principle, we develop an injection locking system by using the modular FPGA architecture and the Verilog programming language. To demonstrate the program's viability, Vivado software is utilized for online simulation and debugging to guarantee the correctness of time conversion between different modules. The simulation results show a good time match between the master and slave lasers. The realization of seed injection locking is verified by detecting the increase of output laser energy, shortening pulse setup time and single longitudinal mode output pulse after injection. Finally, a 2 μm single frequency pulse laser is generated with a repetition rate 300 Hz and output power 4.5 mJ.