Optical Shock-Enhanced Self-Photon Acceleration
arXiv:2107.09575 · doi:10.1103/PhysRevA.104.043520
Abstract
Photon accelerators can spectrally broaden laser pulses with high efficiency in moving electron density gradients. When driven by a conventional laser pulse, the group velocity walk-off experienced by the accelerated photons and deterioration of the gradient from diffraction and refraction limit the extent of spectral broadening. Here we show that a laser pulse with a shaped space-time and transverse intensity profile overcomes these limitations by creating a guiding density profile at a tunable velocity. Self-photon acceleration in this profile leads to dramatic spectral broadening and intensity steepening, forming an optical shock that further enhances the rate of spectral broadening. In this new regime, multi-octave spectra extending from wavelengths, which support near-transform limited pulses, are generated over m of interaction length.