Photonic time stretch for broadband stimulated Raman scattering

In this paper, we illustrate a novel approach to broadband SRS, based on Photonic Time Stretch (PTS) [4]. This technique can acquire single-shot optical spectra at up to tens of MHz repetition rates by a high-speed analog to digital conversion [5]. Fig. 1(a) depicts our PTS-SRS setup. A narrowband pump (at 1.03Pm) and a broadband Stokes (at 1.50Pm, with 50-nm bandwidth) are focused on the sample to generate the Raman signal. After the sample, a grating pre-stretcher and an 18.6km-long single-mode fiber disperse the Stokes pulse to a final duration of a few tens of nanoseconds. A fast photodiode and a high-speed oscilloscope finally acquire its temporal profile, which is uniquely mapped into a spectrum by simply calibrating the dispersion introduced.