Whispering Gallery Mode Photonic Devices

Whispering gallery mode (WGM) photonic devices confine light by continuous total internal reflection around the periphery of a dielectric microcavity. The circulating optical fields build up high intensities and exceptionally high quality factors (Q), enabling ultralow‐threshold lasing, narrow‐linewidth filters and extreme refractive‐index sensitivity. WGMs can be supported in diverse geometries—including microdisks, microtoroids, microrings and microgoblets—fabricated from platforms such as silica, silicon, polymers and hybrid composites. Coupling to and from these resonators is typically achieved by tapered fibres, prism couplers or on‐chip waveguides. Advances in materials and fabrication, including two‐photon polymerisation, ink‐jet printing and 3D laser writing, have driven miniaturisation and integration with electronic and fluidic systems. Tunability has been realised by thermal, mechanical and all‐optical methods, broadening the scope of applications in telecommunications, environmental monitoring and biomedical sensing. The global significance of WGM devices lies in their compact footprint, compatibility with established foundry processes and their ability to deliver high performance at low cost, laying the groundwork for next‐generation photonic circuits and lab‐on‐a‐chip technologies.

Research from Nature Portfolio

Recent studies have demonstrated a single‐mode laser with side‐mode suppression ratios exceeding 20 dB using size‐mismatched triple‐coupled microrings. By precisely engineering ring radii and inter‐ring gaps to control the free spectral range, a dominant lasing mode emerges via the Vernier effect while suppressing higher‐order modes. Numerical simulations corroborate experimental results, confirming stability across a wide power range. Another foundational work reports polymeric microcavities doped with Rhodamine B fabricated by femtosecond laser direct writing. These structures achieve lasing thresholds as low as 12 nJ under pulsed excitation, highlighting the potential of single‐step polymer processing for flexible, high-Q microdevices. Collectively, these developments underscore the interplay between structural engineering and material choice in achieving ultralow‐threshold, single‐frequency sources and high-quality sensors.

Whispering Gallery Mode Photonic Devices publication trend

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

Technical terms

Whispering gallery mode (WGM): Optical resonance arising from light circulating by total internal reflection along a curved dielectric boundary.

Quality factor (Q): Dimensionless parameter indicating the energy storage efficiency of a resonator, defined by the ratio of stored energy to energy dissipated per cycle.

Free spectral range (FSR): Wavelength or frequency spacing between adjacent resonant modes in a cavity.

Vernier effect: Mode‐selection mechanism in coupled resonators where overlapping resonances enhance one mode while suppressing others.

Evanescent field: Decaying electromagnetic field extending beyond the resonator boundary, enabling coupling and sensing interactions.

References

1. High side-mode suppression ratio with a Vernier effect single-mode laser using triple coupled microrings. Scientific Reports (2023).
2. Low threshold Rhodamine-doped whispering gallery mode microlasers fabricated by direct laser writing. Scientific Reports (2017).
3. Tunable photonic devices by 3D laser printing of liquid crystal elastomers. Optical Materials Express (2020).
4. Optically tunable microresonator using an azobenzene monolayer. AIP Advances (2020).
5. Robust label-free biosensing using microdisk laser arrays with on-chip references.. Optics Express (2018).