Whispering gallery modes (WGMs) are phenomena where sound or light waves travel along curved surfaces, repeatedly reflecting and staying confined near the boundary, allowing the waves to travel long distances with little loss.
How WGMs Work:
- Waves propagate by grazing the inner surface of a curved structure, such as a dome or circular cavity.
- Continuous total internal reflection traps the waves close to the surface.
- This confinement creates resonant modes where waves interfere constructively, enhancing certain frequencies.
Examples:
- In acoustics, whispers can be heard clearly across large domed spaces (like St. Paul’s Cathedral), as sound hugs the curved wall.
- In optics, WGMs occur in microresonators and microspheres, confining light for applications like lasers, sensors, and filters.
Importance:
- WGMs enable high-quality resonance with minimal energy loss.
- They are used in precision measurement, enhancing sensitivity in biosensors and optical communication devices.
- Understanding WGMs helps in designing architectural spaces with unique acoustic properties.
Whispering gallery modes reveal how geometry and wave behavior combine to guide waves efficiently along curved surfaces, producing striking effects in both sound and light.