Whispering gallery mode (WGM) refers to a phenomenon in wave physics, particularly in optics, where waves, such as light or sound waves, are trapped and circulate along the periphery of a curved surface. The term "whispering gallery" is derived from the acoustic behavior observed in certain architectural structures, like domes or circular galleries, where whispers or sounds made at one point can be heard clearly at another distant point due to multiple reflections along the curved surface.
In the context of optics, whispering gallery modes are often associated with microresonators or optical cavities that have a curved or spherical geometry. These structures allow light waves to travel along the circumference, repeatedly reflecting off the curved surface. The phenomenon is particularly pronounced when the circumference of the structure is an integer multiple of the wavelength of the light, leading to constructive interference and the enhancement of certain modes.
Whispering gallery modes have practical applications in various fields, including optics and photonics. Microresonators based on whispering gallery modes are used in devices like microcavities, sensors, lasers, and filters. The highly confined and resonant nature of these modes can be exploited for enhancing the interaction of light with materials, enabling the development of sensitive sensors and compact optical components.