Dual-comb based time-stretch optical coherence tomography for large and segmental imaging depth

Abstract

Optical coherence tomography based on time-stretch enables high frame rate and high-resolution imaging for the inertia-free wavelength-swept mechanism. The fundamental obstacle is still the acquisition bandwidth's restriction on imaging depth. By introducing dual-comb with slightly different repetition rates, the induced Vernier effect is found to be capable of relieving the problem. In our work, a dual-comb based time-stretch optical coherence tomography is proposed and experimentally demonstrated, achieving a 1.5-m imaging depth and 200-kHz A-scan rate. Moreover, about a 33.4-µm resolution and 25-µm accuracy are achieved. In addition, by adjusting the frequency detuning of the dual-comb, the A-scan rate can be further boosted to video-rate imaging. With enlarged imaging depth, this scheme is promising for a wide range of applications, including light detection and ranging.

Mid-infrared single-photon upconversion spectroscopy enabled by nonlocal wavelength-to-time mapping

“…In the frequency upconversion process, the quantum-correlated properties of MIR photons are well maintained. The conjugated NIR heralding photons from photon pairs are routed via a 10-km single-mode fiber (SMF) to acquire group velocity dispersion (GVD), enabling wavelength-to-time mapping (35)(36)(37)(38)(39). Because of the quantum correlation inherited by the upconverted photons, we successfully implement correlation measurement that nonlocally maps the spectral information contained by the MIR signal photons into the time domain.…”