Continuous-streaming high-speed two-photon dual-comb LiDAR with free-running lasers.

Dual-comb distance metrology combines sub-µm precision with absolute distance measurement over meter-scale non-ambiguity ranges. The most common interferometric implementation requires sophisticated approaches to achieve continuous streaming due to the need for digitization at near-gigasample/s rates. Here, we exploit the naturally low data burden of two-photon dual-comb LiDAR to demonstrate continuously-streamed distance metrology at up to 20 kHz, reaching a precision of nearly 1 µm in an averaging time of 10 ms. Using free-running 500 MHz Er,Yb:glass femtosecond lasers, we achieve sampling rates sufficient to demonstrate the capture of a four-minute audio track from the displacement of a loudspeaker-mounted mirror. The ability to perform high-speed yet low-data-burden distance metrology using unstabilized lasers presents exciting opportunities for diverse applications in industrial machine-tool control and calibration.