Single-Shot Terahertz Time Profiling Using Curved Wavefront

We report an improved single-shot electro-optic sampling (EOS) based detection scheme to measure the time profile of a terahertz (THz) pulse using inherent curvature of a converging wavefront. A simple addition to conventional multishot EOS technique enables single-shot recording of THz time profile. While the temporal resolution of the proposed method is limited only by the duration of the probe laser pulse, the spatial resolution can be externally controlled with ease. Our method is easy to implement and has the potential to provide better signal-to-noise ratio compared to other single-shot methods. An interesting spin-off of the proposed technique is that the quintessential space-to-time calibration process itself reveals the spatial profile of the THz radiation. The technique is simple yet versatile and capable of characterizing THz radiation emitted by high-power THz sources employing ultrashort intense lasers and modern-day particle accelerators. As a proof of principle demonstration, we provide measurement and characterization of the THz pulse emitted by two-color laser-produced plasma in ambient atmosphere using 45 fs Ti:sapphire laser pulses. Our method faithfully reproduces the THz waveform measured by conventional scanning EOS technique.