Reduction of intensity noise of single-frequency Nd:YVO4 laser using mode cleaner

The mode-cleaner consisting of a ring cavity with three mirrors was designed based on the theoretical analyses and experimental measurements of the intensity noise spectra for an all-solid-state laser. The intensity noise of a homemade single-frequency Nd:YVO4 laser has been significantly decreased by the use of mode-cleaner with the characteristic of filtering high frequency noise. The noise frequency at which the shot-noise-limit is reached has been reduced to 7 MHz from 30 MHz. In design, the requirements of both narrow bandwidth and higher transitivity for the cavity were considered compatibly. The transitivity of mode-cleaner is 70%.