Dual comb-based characterization of rapidly tuned lasers

Time-resolved, high-accuracy and high-resolution spectroscopy of rapidly tuned cw lasers is critical to realizing their full potential for sensing, but is not possible with conventional spectrometers. We demonstrate a coherent dual-comb-based spectrometer capable of measuring the instantaneous frequency of cw optical waveforms up to chirp rates of 1500 THz/s over a span of 5 THz with time-bandwidth limited precision. Provided there is a brief (<; 1 ms) period of low laser chirp (<;160 GHz/s) during the waveform measurement, the absolute frequency accuracy can be calibrated to an accuracy within 2.5 kHz, depending on the underlying frequency reference. This approach should enable optimized waveforms for sensing applications including multi-species gas detection, coherent laser radar, and optical metrology.