STUDY OF A BALANCED HOMODYNE DETECTOR WITH HIGH COMMON-MODE NOISE SUPPRESSION FOR QUANTUM OPTICS EXPERIMENTS

Abstract

This paper presents the design, construction, and performance evaluation of a balanced homodyne detector (BHD) intended for continuous-variable quantum optics applications. The system employs two closely matched IG17X500 photodiodes and a low-noise differential amplifier to suppress classical technical noise and enhance the sensitivity of quadrature measurements. Experimental tests using a 1064 nm Nd:YAG laser demonstrate strong photodiode linearity and a quantum efficiency of approximately 68%. Spectral analysis further reveals a Common-Mode Rejection Ratio (CMRR) of around 52 dB, indicating highly effective cancellation of laser-induced and electronic noise. A characteristic relaxation-oscillation peak at 284.375 kHz is observed in the unbalanced detector output but significantly reduced in the balanced output, confirming the robustness of the homodyne architecture. These results verify that the implemented BHD operates near the shot-noise limit and is well suited for applications such as squeezed-state detection, vacuum noise characterization, and precision continuous-variable quantum measurements.