Noncollinear single-shot detection of terahertz waves

We demonstrate a single-shot temporal imaging technique for terahertz (THz) waves based on spatially resolved nonlinear frequency mixing. By employing sum or difference frequency generation (SFG or DFG) in a non-collinear geometry, our method maps the temporal evolution of a THz field into a spatially encoded near-infrared (NIR) signal. The angular separation of the generated NIR photons, governed by phase-matching conditions, enables the time-dependent THz waveform to be mapped directly onto a camera without the need for mechanical time-delay scanning. It provides real-time, high-resolution access to ultrafast THz dynamics in single-shot interactions, operating at the laser repetition rate and limited only by the acquisition speed of the line-scan camera. These results pave the way for advanced THz diagnostics in experimental setups where scanning is impractical or real-time access is mandatory.