Single-photon dual-comb ghost imaging spectroscopy

Single-photon spectroscopy utilizing single-pixel binary detectors, often statistically recovers "high-dimension" spectral information from "low-dimension" photon-counting signals with ultra-high sensitivity. Nevertheless, it has been a significantly long-standing challenge to achieve either high-speed or high-resolution spectral measurements under photon-deficient scenarios. This study proposes single-photon dual-comb ghost imaging spectroscopy (DC-GIS), which utilizes a mode-resolved dual-comb matrix to interrogate the sample and directly calculates the high-resolution spectrum from photon-counting signals in milliseconds through ghost-imaging method. The concept of single-photon DC-GIS has been examined by measuring the vib-rotational transitions of acetylene with a resolution of 125 MHz and a measurement time of 6.4 ms, and ultra-long distance (125 km) fiber sensing based on phase-shifted fiber Bragg grating with an ultra-high sensitivity of 0.5 με with femtowatt-level power per comb line. This approach brings the high-speed and high-resolution spectroscopy to the cutting-edge research of photon-scarce scenarios.