Whispering-Gallery Mode Microcavity Lasers

Whispering-gallery mode microcavity lasers exploit optical resonances confined by continuous total internal reflection around the periphery of micro-scale dielectric structures. Such resonators, which include microdisks, microrings and microtoroids, achieve exceptionally high quality factors and low mode volumes, enabling lasing thresholds at pico- to microwatt levels under optical or electrical pumping. The tight confinement of light and the circulatory propagation of whispering-gallery modes enhance light–matter interaction with embedded gain media such as quantum dots, quantum wells or nitride semiconductors. By tailoring cavity geometry, refractive index contrast and output coupling schemes, researchers have demonstrated single-mode emission, directional output and on-chip integration, making these devices promising for applications in optical interconnects, sensing, communications and quantum photonics.

Research from Nature Portfolio

Recent studies have introduced novel cavity designs and fundamental insights into mode dynamics. One work proposed a floating gallium nitride microdisk incorporating a vertical slit to perturb the whispering-gallery path. This geometry permits simultaneous control over lasing mode, emission direction and quality factor, while maintaining a low threshold and offering a route to compact on-chip optical interconnects. An earlier foundational investigation revealed resonance-assisted tunnelling in deformed two-dimensional microcavities. By mapping phase-space separatrices, the study quantified strong inter-mode interactions induced by boundary deformation and identified selection rules based on angular momentum. These findings furnish a principled basis for engineering mode coupling and unlocking unconventional lasing regimes in non-circular resonators.

Research from all publishers

Advances in microcavity arrays and on-chip integration have broadened the scope of whispering-gallery lasers. A recent report on GaN-on-silicon microring lasers demonstrated unidirectional emission through a metal-coated sidewall and a directly coupled waveguide. The configuration suppressed isotropic leakage, enhanced light collection efficiency and enabled integration with an on-chip photodetector, highlighting a viable platform for silicon-based optoelectronics. In parallel, investigations into periodic lattices of coupled microcavities have unveiled a novel universality class of wave chaos. Cavity-momentum locking in such crystal arrangements reconfigures phase-space dynamics, inducing dynamical localisation transitions and modifying inter-cavity coupling. These insights offer new strategies for controlling collective lasing behaviour in resonator arrays.

Whispering-Gallery Mode Microcavity Lasers publication trend

The graph below shows the total number of articles in whispering-gallery mode microcavity lasers across all publications each year (not limited to Nature Index journals).

Technical terms

Whispering-gallery mode (WGM): An optical resonance in which light circulates around a dielectric boundary via continuous total internal reflection, yielding high confinement and low loss.

Quality factor (Q): A dimensionless parameter expressing the ratio of stored optical energy to energy lost per oscillation, indicating resonator performance and spectral linewidth.

Mode volume: The effective spatial extent of an optical mode within a cavity, inversely related to the intensity of light–matter interaction.

Resonance-assisted tunnelling: A process in deformed microcavities whereby modes traverse classically forbidden regions via overlapping resonances, enabling strong inter-mode coupling.

Dynamical localisation: A wave phenomenon in which chaotic phase-space dynamics become confined to regular regions, suppressing classical diffusion and altering mode distributions.

References

1. Bloch theorem dictated wave chaos in microcavity crystals. Light: Science & Applications (2023).
2. Unidirectional emission of GaN-on-Si microring laser and its on-chip integration. Nanophotonics (2023).
3. Whispering-Gallery Mode Lasing in a Floating GaN Microdisk with a Vertical Slit. Scientific Reports (2020).
4. Nonlinear resonance-assisted tunneling induced by microcavity deformation. Scientific Reports (2015).