Single-Pixel Fluorescence Spectroscopy Using Near-Field Dispersion for Single-Photon Counting and Single-Shot Acquisition

Time-resolved sensing of fluorescence quanta provides exceptionally versatile information–including access to nanoscopic structure, chemical environment and nonclassical behavior of quantum emitters. Combined spectro-temporal information is typically obtained using spatial dispersion with photoelectron imaging such as streak-cameras or position-sensitive counting and, alternatively, sequential filtering with single-pixel detectors. However, such schemes require complex, expensive and low-sensitivity detectors or rely on scanning acquisition. Here, we demonstrate a single-pixel implementation of fluorescence emission spectroscopy entirely in the temporal domain compatible with (a) time-correlated single-photon counting (TCSPC) and (b) high-speed single-shot detection. Harnessing the near-field regime of the Time-Stretch Dispersive Fourier Transformation (TS-DFT), we encode spectral information via chromatic dispersion into temporal signals, and we demonstrate the retrieval of entwined information via a direct deconvolution using prior knowledge. Addressing high optical throughput for extended emitters, we introduce a high-bandwidth graded-index multimode fiber for TS-DFT. As proof-of-concept, we present rapid single-shot optical thermometry based on quantum-dot luminescence. Given its high speed, efficiency, and simplicity, we foresee broad applications for fast hyperspectral confocal fluorescence microscopy, low-light sensing, and high-throughput spectral screening.