Detection Schemes for Two-Mode Squeezed Fiber Optic Sagnac Interferometry

The fiber optic Sagnac interferometer can measure the rotation rate of a system with a high sensitivity. However, they require a large sensor area, which leads to a huge footprint and size compared with their micro-electromechanical systems (MEMS) counterpart. Consequently, the performance decreases when using chip-integrated Sagnac interferometers with small sensor areas. In this letter, we address this issue and present a method to improve the sensitivity at a small scale. Therefore, we utilize two-mode squeezed light that can be generated in a ring resonator via four-wave mixing, which can have a very low noise. We show that the combination of classical coherent light and squeezed light can improve the sensor performance compared with a classical fiber optic Sagnac interferometer. For this purpose, we discuss two different configurations that are suited for various applications. The first one makes use of the low noise of squeezed light and is suited for small- and low-loss systems using intensity difference measurements, while the second one measures the variance of squeezed light via product detection and is suited for larger and lossy systems.