Whispering-gallery wave known as surface plasmons has been demonstrated in the form of whispering-gallery waves, and likewise for exciton-polaritons in semiconductors. Galleries simultaneously containing both acoustic and optical whispering-gallery waves have also been made, exhibiting very strong mode coupling and coherent effects. Hybrid solid-fluid-optical whispering-gallery structures have been observed as well. Whispering-gallery wave Whispering-gallery waves, or whispering-gallery modes, are a type of wave that can travel around a concave surface. Originally discovered for sound waves in the whispering gallery of St Paul’s Cathedral, they can exist for light and for other waves, with important applications in nondestructive testing, lasing, cooling and sensing,
Whispering-gallery wave acoustic diffraction (lateral wave spreading) are then completely compensated. Whispering-gallery waves exist for light waves. They have been produced in microscopic glass spheres or toruses, for example, with applications in lasing, optomechanical cooling, frequency comb generation and sensing. The light waves are almost perfectly guided round by optical total internal reflection, leading to Q factors in excess of 10 being achieved. This is far greater than the best values, about 10, that can be similarly obtained in acoustics. Optical modes in a whispering gallery resonator are inherently lossy due to a mechanism similar to quantum tunneling. As a result, light