Application of an optical pulse stretcher to coherent anti-Stokes Raman spectroscopy.

An external optical cavity pulse stretcher for nanosecond-long laser pulses has been applied to coherent anti-Stokes Raman spectroscopy (CARS). An increased signal-to-noise ratio was achieved for both vibrational and pure rotational CARS, while the power density of the laser beams remained constant. Moreover, it was demonstrated that the use of the pulse stretcher also leads to improved precision of the determined temperatures and concentrations as a result of repeated excitation of the dye laser.