Large-area low-noise resonant photodetector for high-sensitivity stimulated Raman scattering spectroscopy and imaging

We report a low-noise compensated tuned amplifier (cTAMP) architecture optimized for large-area photodiodes in stimulated Raman scattering (SRS) detection. By integrating a tunable RLC feedback network with a matching compensation inductor, the design simultaneously achieves resonance enhancement and amplifier stability despite the high junction capacitance of a 10 × 10 mm² photodiode. As a proof of concept, a detector configured for 20 MHz center frequency and 1 MHz bandwidth exhibits an output-referred noise floor of 31<i>nV</i>/<i>Hz</i>, enabling shot-noise-limited linear operation from 0.1 mW up to 36 mW optical power under ∼50 μs time constant in the near-IR region. This wide dynamic range and low noise performance allow faithful characterization of high-power squeezed states that saturate conventional detectors, as verified in photon-number squeezing experiments. In addition, the detector facilitates biocompatible ultrafast SRS microscopy with milliwatt-level excitation, supporting hyperspectral live cell imaging without compromising sensitivity. These results establish the cTAMP-based detector as a versatile platform for high-sensitivity quantum optics and biomedical imaging, with potential for extension to other modulation-based optical measurements.