Experimental investigation about the influence of pump phase noise on phase-correlation of output optical fields from a non-degenerate parametric oscillator

The influence of the phase fluctuation of the pump laser on the phase correlation between the signal and idler modes of the output fields from a non-degenerate optical parametric oscillator operating above oscillation threshold was experimentally investigated. The noise spectra of the intensity-difference and the phase-sum of the entangled optical beams were measured with a pair of unbalanced fiber Mach-Zehnder interferometers specifically designed. The experimental results prove the previous theoretical prediction and are in reasonable agreement with the calculation based on semiclassical theory involving the phase fluctuation of pump laser.