Single pulse stimulated Raman photothermal (spSRP) microscopy using an OPA

Stimulated Raman photothermal (SRP) is a newly developed chemical imaging scheme that probes the SRS induced thermal effect with a third laser beam. SRP shows high sensitivity, where a >500-fold boost of modulation depth comparing to SRS has been achieved. To further improve the sensitivity of SRP, we introduce spSRP with a ~1 MHz repetition rate, high peak power OPA laser serving as the SRP excitation source. The high peak power increases the energy deposition of SRS process, enables SRP measurement with a single pair of pump and Stokes laser pulses. spSRP is a firm step towards vibrational spectroscopic imaging with ultrahigh sensitivity.