Broadband stimulated Raman scattering microscopy with wavelength‐scanning detection. (3rd January 2020) - De la Cadena, Alejandro
Abstract: We introduce a high‐sensitivity broadband stimulated Raman scattering (SRS) setup featuring wide spectral coverage (up to 500 cm −1 ) and high‐frequency resolution (≈20 cm −1 ). The system combines a narrowband Stokes pulse, obtained by spectral filtering an Yb laser, with a broadband pump pulse generated by a home‐built optical parametric oscillator. A single‐channel lock‐in amplifier connected to a single‐pixel photodiode measures the stimulated Raman loss signal, whose spectrum is scanned rapidly using a galvanometric mirror after the sample. We use the in‐line balanced detection approach to suppress laser fluctuations and achieve close to shot‐noise‐limited sensitivity. The setup is capable of measuring accurately the SRS spectra of several solvents and of obtaining hyperspectral data cubes consisting in the broadband SRS microscopy images of polymer beads test samples as well as of the distribution of different biological substances within plant cell walls. Abstract : We introduce a high‐sensitivity broadband stimulated Raman scattering (SRS) setup featuring wide spectral coverage (up to 500 cm −1 ) and high‐frequency resolution (≈20 cm −1 ). A single‐channel lock‐in amplifier connected to a single‐pixel photodiode measures the Stimulated Raman loss signal, whose spectrum is scanned rapidly using a galvanometric mirror after the sample. We use the in‐line balanced detection approach to suppress laser fluctuations. We present the SRS spectra of solvents as well as microspectroscopy data of reference microstructures and plant samples.