Harald gives a presentation online on Waves and nonlinear wave mixing in high quality optical resonators at this years KOZwavinar.
Waves bounded by convex boundaries can from a phenomenon called Whispering Gallery Modes. The name stems from acoustic waves creeping along a convex wall, such as found in Temple of Heaven or the St Paul’s Cathedral, first described mathematically by Lord Rayleigh. We use a similar phenomenon in circularly shaped disks of dielectric materials, where the electromagnetic radiation is trapped via total internal reflection close to the rim of the disk. As total internal reflection in a transparent structure much larger than the wavelength is nearly lossless, the confinement can be very high, leading to very localized and high electromagnetic fields.
We use such high quality whispering gallery modes to harness non-linear effects within the dielectric, in particular the second order nonlinear effects such as sum- and difference frequency generation, where two electromagnetic fields of different frequency can produce fields at either the sum or the difference frequency. The talk will provide the background and show application of these resonator for the generation of optical frequency combs and for quantum transduction.