Phase-contrast CARS spectroscopy with rapid phase modulation

We demonstrate a novel method of phase-contrast CARS spectroscopy by using an optical bandpass filter and a mechanical modulator instead of a 4f pulse shaper used in previous studies. Our system has several advantages over the conventional one; the simplicity of the setup, a larger throughput, and the higher data rate of measurements. We use the known vibrational frequencies of chloroform to verify the efficacy of this method.