Direct temporal shaping of terahertz light pulses

Abstract

Active terahertz (THz) waveform synthesis is desirable for a broad range of applications including high speed wireless communications at Tb/s speeds and coherent manipulation of quantum systems driven by engineered light fields. In this work, we demonstrate an all-optical, fully reconfigurable platform for direct and arbitrary temporal shaping of broadband THz light pulses. The technique is based on an array of line photoexcitations of charge carriers within an otherwise homogeneous semiconductor embedded within a parallel plate waveguide. The spatially periodic charge distributions locally modulate the THz dielectric function, mapping each photoexcited line in the array directly to a reflected single-cycle THz pulse. By tuning the spatial distribution of the line excitations, arbitrarily shaped THz pulse sequences can be created from a single THz input pulse with relatively little intrinsic loss. We demonstrate synthesis of multi-cycle THz waveforms, 8-bit digital pulse sequences, and THz frequency combs with control over amplitude, central frequency, and linewidth.