2025/10/02 by Ozora Iso, Iso, Ozora, Onoda, Koya +9 · 1 citation
Engineering · Biochemistry, Genetics and Molecular Biology · Physics and Astronomy · #Photoacoustic and Ultrasonic Imaging #Advanced Fluorescence Microscopy Techniques #Laser-Matter Interactions and Applications
paper · pdf · doi:10.48550/arxiv.2510.01836
Joint spectral measurements are a powerful tool for characterising biphoton spectral correlation, which is crucial for quantum information and communication technologies. In these applications, highly pure biphoton states are essential in any time- and frequency-mode, often obviating the need for time-resolved measurements. Conversely, spectroscopy utilising entangled photon pairs is gaining significant attention for its ability to unveil molecular dynamics, a field that critically demands time-resolved capabilities. Here, we introduce a methodology for capturing a biphoton spectrum that comprises visible and near-infrared photons, resulting in a highly non-degenerate joint spectrum. Our system employs two non-scanning spectrographs: a fibre spectrometer for near-infrared photons and a delay-line-anode single-photon imager for visible photons. We successfully measure the joint spectral intensity by leveraging a time-tagging acquisition strategy. Furthermore, our approach uniquely enables time-resolved joint spectral measurements with respect to the laser synchronisation against the hundreds-of-picosecond instrument response function. Our methodology could advance heralded fluorescence spectroscopy using biphoton sources to investigate temporal dynamics of complex biological, chemical, and physical systems.