Invited Article: CARS molecular fingerprinting using sub-100-ps microchip laser source with fiber amplifier

Abstract

We have developed an ultrabroadband multiplex coherent anti-Stokes Raman scattering (CARS) microspectroscopic system using a supercontinuum (SC) seeded by sub-100-ps (85 ps) laser pulses with a sub-MHz (0.82 MHz) repetition rate. Because of the high peak power and ultrabroadband spectral profile of the SC, we can efficiently generate multiplex CARS signals in the spectral range of 600-3600 cm−1, which covers the entire molecular fingerprint region, as well as the C - H and O - H stretching regions. Due to the high peak power of the new laser source, the exposure time (pixel dwell time) for CARS imaging of polymer beads was reduced to less than 1 ms (0.8 ms), which was limited by the readout time of a CCD camera. Owing to the improvement in CARS spectral quality, clear molecular fingerprinting was achieved for living HeLa cells at different phases in the cell cycle.