Ballistic electrons generate nonlinear optical signals without needing intense laser power/ exotic materials, furthering next-gen THz devices

https://phys.org/news/2025-05-ballistic-electrons-gen-terahertz-devices.html

"traditional nonlinear materials rely on high-intensity lasers, overcome using optical resonators shaped like bow ties to funnel electrons through narrow junctions, double incoming light frequency... utilizes how electrons scatter off resonator walls: when surfaces smooth, electrons reflect predictably (specular scattering) enabling asymmetrical movement... field intensities 1K to 10K times lower, enabling use of compact, low-power IR sources, for building tunable nanoscale THz rectifiers/ photodetectors needing no applied voltage"