Subharmonic Synchronization of Picosecond Yb Fiber Laser to Picosecond Ti:Sapphire Laser for Stimulated Raman Scattering Microscopy

We demonstrate a subharmonically synchronized picosecond laser system and its application to stimulated Raman scattering (SRS) microscopy for label-free biological imaging with high sensitivity and high spectral resolution. Experimentally, 5.5-ps Yb fiber laser pulses at a repetition rate of 38 MHz were successfully synchronized to 4.8-ps Ti:Sapphire laser pulses at a repetition rate of 76 MHz, by using a two-photon detector, an intracavity electro-optic modulator, and a piezoelectric transducer. The temporal jitter was measured to be 120 fs. These pulses were applied to SRS microscopy. We confirmed the shot-noise-limited sensitivity, and succeeded in SRS spectroscopy of a polymer bead as well as three-dimensional SRS imaging of a HeLa cell.