Optimization of a Frequency Comb-Based Calibration of a Tunable Laser

摘要

We analyze in detail a scheme of the comb-calibrated frequency-modulated continuous-wave (FMCW) laser and study the accuracy of the laser frequency measurements. In this scheme the moment when the tunable laser frequency crosses the reference comb lines is obtained by filtering the heterodyne signal between the frequency comb and the tunable laser with a narrow band-pass filter. We show that the accuracy of the measured instantaneous frequency depends on the frequency sweep speed, bandwidth filter parameters and total phase noise of the laser and applied frequency comb. In this work we present the optimal ratio of frequency sweep and filter bandwidth for the given total phase noise and type of narrowband filter providing the highest frequency calibration accuracy.