Focusing an invisible mid-infrared laser beam into a lead halide perovskite generates bright green photoluminescence, arising from a strong field-driven electron tunneling process.

A custom metallic waveguide enhances local THz fields by confining the mode volume below the diffraction limit. This enables stronger fields than free-space focusing, facilitating access to highly nonlinear light–matter interactions in the sample.

To detect terahertz radiation, an optical probe pulse is divided by an echelon mirror into hundreds of spatially and temporally separated pulselets, enabling a "single-shot" readout of the terahertz waveform.

Intense terahertz fields are generated by optical rectification of near-infrared laser pulses in a LiNbO3 prism; simultaneously, the accompanying second-harmonic generation process results in the strong emission of purple light.