Time-Domain Coherent Anti-Stokes Raman Scattering Signal Detection for Terahertz Vibrational Spectroscopy Using Chirped Femtosecond Pulses

A new scheme for low-frequency coherent anti-Stokes Raman scattering spectroscopy (CARS) using chirped femtosecond pulses is proposed and demonstrated. Two chirped broadband optical pulses created terahertz (THz) polarization in the sample and generated CARS signal. The chirped CARS signal was then compressed by a pulse compressor and detected by a time gating technique. A resonant Raman band of GaSe at around 0.6 THz was successfully observed with the time-domain CARS technique. With the present system, CARS spectra from 0.2 to 5 THz are obtainable. (C) 2010 The Japan Society of Applied Physics