Abstract
Frequency-sweep nonlinearity limits the resolution and stability of coherent optical sensing systems. We present a simple optical-feedback-based method that uses the beat signal from a stationary target to characterize the instantaneous sweep rate and iteratively predistort the frequency-tuning waveform, without an auxiliary interferometer or external frequency reference. Experiments with a PZT-tuned 1064 nm frequency-swept microchip laser reduce beat-frequency variance to 0.049 kHz
2
(>99% suppression) and compress the overall spectral width by more than 60%, demonstrating effective source-level linearization in both sweep directions.