Recovery of microcavity spectral readout distortion induced by fast scanning

Optical microcavities have attracted increasing attention for high-performance sensing, where a laser scans the resonance, providing high-resolution and time-sensitive measurements. However, rapid resonance scanning can lead to readout distortions, affecting the accuracy of high-speed sensing. Traditional methods have attempted to alleviate this distortion by examining the relationship between the ringing behavior and the scanning speed or by reconstructing the steady-state spectra. Yet the complexity of distorted readouts often obscures their correlation with well-established steady-state spectra, presenting a significant challenge for transient sensing. In this study, we revisit electromagnetic theory in microcavities and discover that ringing distortion stems from quadratic phase interference between light emitted from the microcavity and the input. Remarkably, this quadratic phase solely arises from the spectral scanning speed, indicating a universality across microcavity types. As a result, the proposed method enables the recovery of a complex steady-state spectrum from a distorted readout at an arbitrary scanning speed after compensating for the introduced phases. This method bridges the gap between transient and steady-state spectra by harnessing the dimensions of spectral scanning speed, offering a promising avenue for high-speed sensing, precision measurement, and advanced scientific research.