Terahertz radiation

Terahertz metamaterials

Photomixing

Optics

Physics

Far-infrared laser

Electromagnetic pulse

Voltage

Terahertz gap

Optical rectification

Ultrashort pulse

Harmonics

Optoelectronics

Laser

Quantum mechanics

Terahertz spectroscopy and technology

Nonlinear optics

Physical Review Letters

The nonlinear interaction of subcycle electromagnetic radiation with matter is the current frontier in ultrafast nonlinear optics and high-field physics. Here, we investigate nonlinear optical effects induced by intense, subcycle terahertz radiation in a doped semiconductor. We observe a truncation of the half-cycle terahertz pulse and an emission of high-frequency terahertz photons. We attribute our observations to the abrupt current drop caused by strong intervalley scattering effects. By adding an extra half-cycle terahertz pulse with opposite polarity, we monitor the evolution of the nonlinear carrier dynamics during a quasi-single-cycle pulse. Our results demonstrate the differences between nonlinear effects for subcycle and multicycle terahertz pulses. It also suggests a new approach to subcycle control of terahertz waveforms, and the generation of high-order terahertz harmonics could be realized by using multicycle pulses.

Subcycle Terahertz Nonlinear Optics