Noise cancellation with phase-detection technique for pump-probe measurement and application to stimulated Raman...

Intensity noise on a probe beam is a serious obstacle to highly sensitive and high-speed pump-probe microscopy. In this report, a reference beam of the probe is prepared and delayed. The intensity modulation by the sample is measured as the phase modulation of the superposition of detected electrical signals of the probe and reference beams, and the intensity noise is canceled. We evaluate performance of the noise cancellation using the super-continuum light from a piece of photonic crystal fiber, and find that the noise is canceled by ∼26  dB. We then apply the method to a stimulated Raman microscope. This method contributes to highly sensitive and high-speed pump-probe imaging with various light sources.