Martin Fejer Date: October 11, 2022 Time: 11– 2 pm Place: Davis Auditorium Host: Alex Gaeta
The combination of tight optical confinement, high-Q resonators, and dispersion engineering available in nonlinear nanophotonics based on third-order (X(3)) nonlinearities in material platforms like silicon nitride have been crucial for the development of contemporary photonics. Notable among these phenomena are soliton mode-locking, supercontinuum generation, and the formation of dissipative Kerr solitons, based on the Kerr-soliton family of solutions, which have had a major impact on metrology, spectroscopy, telecommunications, optical clockwork, and attoscience.
The past few years have seen the development of nanophotonic waveguides and resonators with second-order (χ(2)) nonlinearities, notably in thin-film lithium niobate (TFLN). These waveguides share many of the useful features of (χ(3)) platforms, combined with the diverse interactions possible with the strong χ(2) nonlinearity, and importantly, the availability of periodic patterning of the nonlinear susceptibility for quasi-phasematching (QPM). QPM frees dispersion engineering to focus on dispersion orders beyond phase mismatch, adding wavelength-flexible ultrabroadband operation capabilities. In this talk, I review recent results that utilize dispersion-engineered waveguides with χ(2) nonlinearities to access previously inaccessible operating regimes and energy scales. Examples include saturated second-harmonic generation with femtojoules (as opposed to picojoules) of pulse energy, parametric amplifiers that achieve saturated parametric fluorescence with picojoules (instead of nanojoules) of pulse energy, and new approaches to octave-spanning supercontinuum generation. QPM together with dispersion engineering is also useful in quantum regimes, for example for the generation of spectrally pure single-photon sources.
The latter portion of this talk will discuss scaling laws for dispersion-engineered nonlinear devices and the prospects for realizing strong coupling, where a χ(2) microresonator achieves saturated single-photon nonlinear interactions.