Double-modulation stimulated Raman scattering: how to image up to 16-fold faster

A stimulated Raman microscope is conventionally performed by modulating either the pump or Stokes beam and demodulating the other. Here, we propose a double modulation scheme that modulates both beams at f_m and 2f_m. Exploiting aliasing and reduction of the repetition rate, we show that the proposed double modulation scheme amplifies the signal amplitude by a factor of 1.5, 2, and 4 for different modulation frequencies and experimental realizations for the same average power at the sample. By deriving the noise power for different sources, we show that the double modulation scheme can perform stimulated Raman scattering (SRS) imaging with an up to 16-fold speed improvement as compared with single beam modulation.