Feedback control and nonlinear intensity noise of Nd:YVO4 microchip lasers -: art. no. 043806

A Fully quantum model is used to derive both the intensity noise of a laser operating with an electronic feedback loop and the nonlinear corrections to the noise or the Free-running laser. The implementation of a nonstandard feedback loop on a Nd:YVO4 microchip laser pumped with an amplitude squeezed diode laser permits us to decrease the intensity of the relaxation oscillation noise peak while leaving the low-frequency part of the spectrum unaffected. This procedure also results in a decrease of the noise in the low-frequency region, showing evidence for nonlinear effects in the noise spectrum. The latter are found to be in good agreement with the theoretical predictions. Good agreement between the experimental results and theoretical predictions is also found over the complete frequency range.