Coherent anti-Stokes Raman scattering imaging using silicon photomultipliers.

Silicon photomultipliers (SiPMs) are an emerging solid-state alternative to photomultiplier tubes (PMTs) for low light detection, with similar gain but lower cost and lower operating voltage. We demonstrate coherent anti-Stokes Raman scattering (CARS) imaging in a side-by-side comparison of an uncooled SiPM with an uncooled multialkali PMT as well as a state-of-the-art cooled GaAsP PMT. We determine the optimum reverse-bias voltage for acquiring the best signal-to-noise ratio (SNR) for CARS imaging of lipids at ${2850}\;{{\rm cm}^{ - 1}}$2850cm-1. We find that despite the higher dark counts, the SNR of CARS images acquired with the uncooled SiPM biased at an optimum voltage is better than that of the multialkali PMT and close to that of the cooled GaAsP PMT (${\sim}{1.5}$∼1.5 and ${\sim}{0.8}$∼0.8 times, respectively). This is due to the higher gain and lower excess noise factor related to the pulse height variability in the SiPM.