Quantum Noise Source Based on Shot Noise of a Balanced Photodetector with a Tunable Integrated Optical Beam Splitter

A broadband quantum noise source based on detection of shot noise of a balanced photodetector is demonstrated. Precise electro-optical tuning of the balanced photodetector circuit was carried out by an integrated optical beam splitter constructed in the form of the dual output Mach–Zehnder interferometer on a lithium niobate substrate. The classical component of the detected noise related to the relative intensity noise of a laser diode was suppressed by more than 15 dB. At the maximum laser power of 100 mW, the power spectral density of detected shot noise was 12 dB higher than the level of technical noise of the measuring system in the frequency band above 3 GHz.