Laser Excess Noise Reduction in Optical Phase Shift Measurements

We describe and demonstrate an optical detetion scheme for small electro-optic phase shift measurements. The scheme increases the moduation depth due to the electro-optic effect and allows broadband reduction of laser excess noise in balanced dual- differential detection systems. The scheme is applied in electro- optic phase shift measurement setup for integrated circuit testing, where the excess laser noise is reduced by ~ 20 dB.