An open and flexible digital phase-locked loop for optical metrology

Abstract

This paper presents an open and flexible digital phase lock loop optimized for laser stabilization systems. It is implemented on a cheap and easily accessible FPGA-based digital electronics platform (Red Pitaya) running a customizable open-source firmware. A PC-based software interface allows controlling the platform and optimizing the loop parameters remotely. Several tools are included to allow measurement of quantities of interest smoothly and rapidly. To demonstrate the platform's capabilities, we built a fiber noise canceler over a $400$~m fiber link. Noise cancellation was achieved over a $30$~kHz bandwidth, a value limited mainly by the delays introduced by the actuator and by the round-trip propagation over the fiber link. We measured a total latency of $565$~ns for the platform itself, limiting the theoretically achievable control bandwidth to approximately 225 kHz.

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Review of Scientific Instruments 89, 093103 (2018) and may be found at https://doi.org/10.1063/1.5039344