Application of optical squeezing to microresonator based optical sensors

Abstract

High-Q optical microresonators combine low losses and high optical energy concentration in a small effective mode volume, making them an attractive platform for optical sensors. While light is confined in the microresonator by total internal reflection, a portion of the optical field, known as the evanescent field, extends outside. This makes the mode's resonant frequency sensitive to changes in the surrounding environment. In this work, we explore the quantum sensitivity limits of this type of sensors. We show that using the intracavity squeezing of the light in the microresonator, it is possible to suppress the influence of the optical losses and cancel the undesirable self phase modulation effect, originating from the cubic non-linearity of the microresonators media. As a result, the sensitivity surpassing the shot noise limit can be achieved. An additional sensitivity gain can be obtained by preparing the input light in a squeezed quantum state.