Ultra-intense THz source and extreme THz nonlinearities in condensed matter

摘要

Few-cycle light pulses in the terahertz (THz) spectral domain have evolved into an invaluable probe of low-energy excitations in condensed matter [1]. Novel challenges such as nonlinear THz optics, coherent control, or high-harmonics generation call for enhanced electric field amplitudes. We introduce a new hybrid laser source combining the stability and versatility of a multi-branch Er:fiber seed laser with the high power levels attainable with a Ti:sapphire amplifier. The system provides phase-locked transients tunable from 1THz to beyond 100THz with energies of up to 19μJ and peak fields of 108MV/cm [2]. These values exceed current records by several orders of magnitude. Amplitude and phase information is gained via electro-optic sampling with 8-fs pulses from a numerically optimized nonlinear bulk fiber integrated in the Er:system [3] [see Fig. 1(a)].