Single-photon single-pixel dual-wavelength imaging via frequency spectral harmonics extraction strategy

In this paper, a single-photon single-pixel dual-wavelength imaging technology based on frequency spectral harmonics extraction is proposed. Using the independent repetition frequencies of pulsed light as multiplexed signals, the reconstructed image with optimal quality is obtained via extracting the sum of the intensities of the first 7 harmonics. Meanwhile, the post-pulse and fluctuation noise are effectively eliminated by applying preprocessing to the photon counting sequence, reducing the crosstalk of dual-wavelength to 2.29 × 10^-4. Moreover, the frequency spectral analysis of the photon counting sequence at sub-photon level of per pixel in a single measurement is realized. With 4.5 × 10^-3 photons per pixel in a single measurement, the 256 × 256 image is well reconstructed. Compared to photon counting single-pixel imaging technology, the proposed technique significantly enhances image quality and enables the dual-wavelength imaging with fewer photons. These results can promote the applications of dual-wavelength imaging in extremely low-light scenes.