Experimental study of balanced optical homodyne and heterodyne detection by controlling sideband modulation

TL;DR

This experimental study demonstrates a flexible optical setup capable of switching between homodyne and heterodyne detection by controlling sideband modulation, confirming the expected noise performance difference.

Contribution

The paper presents a novel experimental setup that can switch between homodyne and heterodyne detection modes by manipulating sideband modulation, enabling direct comparison of their noise characteristics.

Findings

Heterodyne detection has twice the noise level of homodyne detection.

The setup can generate single or dual sidebands for different detection schemes.

Confirmed the theoretical noise difference between homodyne and heterodyne detection.

Abstract

We experimentally study optical homodyne and heterodyne detections with a same setup, which is flexible to manipulate the signal sideband modulation. When the modulation only generate a single signal sideband, the light field measurement by mixing the single sideband at $\omega_{0}+\Omega$ with a strong local oscillator at the carrier frequency $\omega_{0}$ on a beam splitter become balanced heterodyne detection. When two signal sidebands at $\omega_{0}\pm\Omega$ are generated and the relative phase of the two sidebands is locked, this measurement corresponds to optical balanced homodyne detection. With this setup, we may confirm directly that the signal-to-noise ratio with heterodyne detection is two-fold worse than that with homodyne detection. This work will have important applications in quantum state measurement and quantum information.