Whispering Gallery Mode Resonators in Optical Systems

Whispering gallery mode resonators confine light by continuous total internal reflection around a curved dielectric interface, enabling exceptionally high quality factors and small mode volumes. Typically fabricated as microspheres, microdisks or microbottles from materials such as silica, soft glasses or crystalline substrates, these resonators support circulating electromagnetic waves whose resonant frequencies are determined by the resonator geometry and refractive index. Coupling light into and out of the resonator is achieved via evanescent fields using tapered fibres, prism couplers or integrated waveguides. The combination of strong optical confinement, narrow linewidths and tunability makes these devices ideal platforms for applications in optical sensing, narrow-linewidth microlasers, nonlinear optics and cavity quantum electrodynamics. Advances in material processing and integration techniques have extended their use to on-chip photonic circuits and fibre-based devices, broadening the scope of precision metrology, environmental monitoring and telecommunication technologies.

Research from Nature Portfolio

Innovative glass-on-glass fabrication techniques yield microbottle-shaped microlasers by melting doped glass onto silica microcapillaries. This approach produces high-Q resonators that lase around telecommunication wavelengths when pumped via a tapered fibre. Thermo-optical tuning is realised by gas flow through the capillary, enabling dynamic control of whispering-gallery modes over tens of gigahertz. Moreover, mechanical strain applied to the structure provides further wavelength tuning, demonstrating multifunctional resonators that combine sensing and coherent light generation in a compact geometry.

Whispering Gallery Mode Resonators in Optical Systems publication trend

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

Technical terms

Whispering-gallery mode (WGM): A resonant optical mode in which light circulates around the periphery of a dielectric structure by total internal reflection.

Quality factor (Q): A dimensionless parameter quantifying the sharpness of a resonance, defined as the ratio of stored energy to energy lost per cycle.

Evanescent coupling: The transfer of optical power between waveguides or a waveguide and a resonator via their overlapping near-field regions.

Mode volume: The effective spatial extent of the electromagnetic field in a resonator, influencing light–matter interaction strength.

Microresonator: A microscopic optical cavity that supports one or more resonant modes, used to enhance light–matter interactions and spectral selectivity.

References

1. Visualizing the Nanoscopic Field Distribution of Whispering-Gallery Modes in a Dielectric Sphere by Cathodoluminescence. ACS Photonics (2023).
2. Recent progress of in-fiber WGM microsphere resonator. Frontiers of Optoelectronics (2023).
3. Comprehensive Numerical Analysis of Temperature Sensitivity of Spherical Microresonators Based on Silica and Soft Glasses. Sensors (2023).
4. Glass-on-Glass Fabrication of Bottle-Shaped Tunable Microlasers and their Applications. Scientific Reports (2016).