Coupling of whispering-gallery modes in size-mismatched microdisk photonic molecules

TL;DR

This paper investigates how whispering-gallery modes couple in microdisk photonic molecules with size mismatches, revealing mechanisms to tune modes and improve fabrication tolerance for microlaser applications.

Contribution

It introduces new insights into WG-mode coupling mechanisms in size-mismatched microdisks, enabling better control of optical properties and fabrication robustness.

Findings

Identifies two coupling scenarios based on size mismatch.

Shows how to tune WG-mode wavelengths and Q-factors.

Proposes design strategies for low-threshold, directional microlasers.

Abstract

Mechanisms of whispering-gallery (WG) modes coupling in microdisk photonic molecules (PMs) with slight and significant size mismatch are numerically investigated. The results reveal two different scenarios of modes interaction depending on the degree of this mismatch and offer new insight into how PM parameters can be tuned to control and modify WG-modes wavelengths and Q-factors. From a practical point of view, these findings offer a way to fabricate PM microlaser structures that exhibit low thresholds and directional emission, and at the same time are more tolerant to fabrication errors than previously explored coupled-cavity structures composed of identical microresonators.