Nonlinear optics articles from across Nature Portfolio

When photons impinge on a material, free electrons can be created by the photoelectric effect. The emitted electron current usually fluctuates with Poisson statistics, but if squeezed quantum light is applied, the electrons bunch up.

Optical recurrent neural networks present a unique challenge for photonic machine learning. Here, the authors experimentally show the first optoacoustic recurrent operator based on stimulated Brillouin scattering which may unlock a new class of optical neural networks with recurrent functionality.

We introduce strong tailored light-wave-driven time-reversal symmetry breaking in monolayer hexagonal boron nitride, realizing a sub-laser-cycle controllable analogue of the topological model of Haldane and inducing non-resonant valley polarization.

We report the NOON-state interference in the frequency domain. Two photons with distinct colors, blue and red, are injected into an interferometer constructed with two frequency beam splitters. The resultant interference pattern is then observed.

Linear topological systems can be characterized using invariants such as the Chern number. This concept can be extended to the nonlinear regime, giving rise to nonlinearity-induced topological phase transitions.

When photons impinge on a material, free electrons can be created by the photoelectric effect. The emitted electron current usually fluctuates with Poisson statistics, but if squeezed quantum light is applied, the electrons bunch up.

I argue that a surface emitting laser that remains single mode irrespective of its size, a scale-invariant laser, should of necessity also waste light at the edge. This is a fundamental departure from the Schawlow-Townes two-mirror strategy that keeps light away from mirrors and edges to preserve gain and minimize loss. The strategy was implemented in the recent discovery of the Berkeley Surface Emitting Laser (BerkSEL).

One-way light transmission can be realized by embracing, rather than mitigating, thermal effects in carefully engineered metasurfaces.