Abstract: A method of performing coherent anti-stokes Raman spectroscopy (CARS) includes generating first and second optical pulse trains having different and adjustable repetition rates. One of the pulse trains is directed in a CW direction and the other in a CCW direction. A frequency shift and a first linear chirp is applied to optical pulses in the first optical pulse train. A second linear chirp is applied to optical pulses in the second optical pulse train. The first and second linear chirps having a common chirp rate. One of the chirped optical pulse trains is used as a pump beam and the other is used as a Stokes beam. The first and second chirped optical pulse trains are combined to define a combined beam. The combined beam is provided to a CARS spectroscopic system for exciting a resonant mode in a sample and generating a CARS signal.