Optical resonators, which circulate and confine light (for instance in lasers), are currently used in a variety of applications of all sizes—from pinpoint light sources smaller than the width of a human hair to kilometer-scale sensing devices such as the Laser Interferometer Gravitational-wave Observatory (LIGO) experiment that detects gravitational waves.
Devices known as optical parametric oscillators are among the widely used nonlinearresonators in optics; they are “nonlinear” in that there is light flowing into the system and light leaking out, but not at the same wavelengths. Though these oscillators are useful in a variety of applications, including in quantum optics experiments, the physics that underpins how their output wavelength, or spectrum, behaves is not well understood.
“When you add strong nonlinearity to resonators, you enter what we call a ‘rich physics regime,'” says Alireza Marandi, assistant professor of electrical engineering and applied physics. “‘Rich’ in physics terms usually means complicated and hard to use, but we need nonlinearities to create useful functionalities such as switching for computing.”
Source: “New Insight into Nonlinear Optical Resonators Unlocks Door to Numerous Potential Applications”, California Institute of Technology