FPGA-Based Optical Cavity Phase Stabilization for Coherent Pulse Stacking

Yilun Xu, Russell Wilcox, John Byrd, Lawrence Doolittle, Qiang Du, Gang Huang, Yawei Yang, Tong Zhou, Wim Leemans, Almantas Galvanauskas, John Ruppe, Chuanxiang Tang (+1 others)
2018 IEEE Journal of Quantum Electronics  
Coherent pulse stacking (CPS) is a new time-domain coherent addition technique that stacks several optical pulses into a single output pulse, enabling high pulse energy from fiber lasers. We develop a robust, scalable and distributed digital control system with firmware and software integration for algorithms, to support the coherent pulse stacking application. We model coherent pulse stacking as a digital filter in the Z domain and implement a pulse-pattern-based cavity phase detection
more » ... e detection algorithm on an FPGA. A 2-stage (2+1 cavities) 15pulse stacking system achieves an 11.0 peak-power enhancement factor. Each optical cavity is fed back at 1.5 kHz, and stabilized at an individually-prescribed round-trip phase with 0.7 deg and 2.1 deg RMS phase errors for Stage 1 and Stage 2 respectively. Optical cavity phase control with nm accuracy ensures 1.2% intensity stability of the stacked pulse over 12 hours. The FPGAbased feedback control system can be scaled to large numbers of optical cavities.
doi:10.1109/jqe.2017.2775698 fatcat:2folnz6twbecfgwqs6j7dqla6e