Nonlinear Cross-Phase Modulation with Intense Single-Cycle Terahertz Pulses

Abstract

We have demonstrated nonlinear cross-phase modulation in electro-optic crystals using intense, single-cycle terahertz (THz) radiation. Individual THz pulses, generated by coherent transition radiation emitted by subpicosecond electron bunches, have peak energies of up to 100 microJ per pulse. The time-dependent electric field of the intense THz pulses induces cross-phase modulation in electro-optic crystals through the Pockels effect, leading to spectral shifting, broadening, and modulation of copropagating laser pulses. The observed THz-induced cross-phase modulation agrees well with a time-dependent phase-shift model.

Intense terahertz pulses from SLAC electron beams using coherent transition radiation

“…Several accelerator-based sources of THz radiation using these approaches have been constructed. [1][2][3][4][5][6][7][8][9][10][11] In CTR from a thin metallic foil, surface currents that match boundary conditions on the foil produce the fields of a collapsing dipole as the electrons approach, and an expanding dipole as they leave, generating an impulse of dipole radiation on both sides. 12 The temporal shape has a long-wavelength cutoff due to the finite size of the foil and apertures.…”

Demonstration of a low-frequency three-dimensional terahertz bullet with extreme brightness

“…However, a large range of THz applications, ranging from ultrafast domain switching [9][10][11] to particle acceleration 12 , requires a giant leap in brightness to match the theoretically predicted needs in field strength being on the order of a few GV m À 1 . Intense THz radiation is mainly generated by employing electron accelerators [13][14][15] and laser-based systems. Although the former has been ahead in terms of intensity, the availability and versatility of lasers are dominating time-resolved THz high-field science.…”

Single-cycle terahertz pulses with >0.2 V/Å field amplitudes via coherent transition radiation

“…Recent progress in laser-based sources has led to pulse energies of roughly 10 µJ and field strengths of order 1 MV/cm for quasi-half-cycle pulses [4][5][6][7] , extending to greater than 10 MV/cm in the few-cycle regime 8 . Other approaches which use relativistic electron beams [9][10][11] have reached similar maximum pulse energies and field strengths [12][13][14][15][16] . Here, we present experimental results obtained by extracting coherent transition radiation (CTR) at the Linac Coherent Light Source (LCLS) free-electron laser 17 , using electron bunches as short as 50 fs.…”