Real-time imaging of standing-wave patterns in microresonators

TL;DR

This paper demonstrates real-time imaging of standing wave patterns in microresonators using SWIR cameras, enabling precise control and measurement for sensing and photonic applications.

Contribution

It introduces a camera-based method for visualizing and controlling standing waves in microresonators, advancing real-time characterization techniques.

Findings

Scattered light intensity correlates linearly with circulating power.

Phase modulation controls standing wave movement.

Enables nanometer-level distance measurements.

Abstract

Real-time characterization of microresonator dynamics is important for many applications. In particular it is critical for near-field sensing and understanding light-matter interactions. Here, we report camera-facilitated imaging and analysis of standing wave patterns in optical ring resonators. The standing wave pattern is generated through bi-directional pumping of a microresonator and the scattered light from the microresonator is collected by a short-wave infrared (SWIR) camera. The recorded scattering patterns are wavelength dependent, and the scattered intensity exhibits a linear relation with the circulating power within the microresonator. By modulating the relative phase between the two pump waves, we can control the generated standing waves movements and characterize the resonator with the SWIR camera. The visualized standing wave enables subwavelength distance measurements of scattering targets with nanometer-level accuracy. This work opens new avenues for applications in on-chip near-field (bio-)sensing, real time characterization of photonic integrated circuits and backscattering control in telecom systems.