Design of an FPGA-based PID controller with high-bandwidth and auto-relocking features: application to Sub-kHz external cavity diode lasers

Narrow line width lasers with high stability are a key enabling technology in high-impact applications such as quantum technologies and laser surgery. On the one hand, stabilizing such lasers implies the design of efficient Proportional-Integral-Derivative (PID) controllers. On the other hand, high end applications require PID controllers with very high regulation bandwidth, relocking feature and easy to adjust parameters. In order to tackle these challenges, we designed and enhanced a PID controller using the pipeline technique. This allowed us to improve the sample rate at which the controller operates. The designed PID has been successfully used in a VBG based external cavity for laser stabilization with ultra-narrow line width.