Speaker: Dr. Christoph Lange, University of Regensburg, Germany
Abstract
Ultrafast charge transport in strongly biased semiconductors lies at the heart of high-speed electronics, electro-optics and fundamental solid-state physics. Intense phase-locked terahertz (THz) pulses at photon energies far below electronic interband resonances may serve as a precisely adjustable alternating bias, far exceeding dc breakdown voltages. In this talk, I will show how extremely large electric fields of up to 72 MV/cm at 30 THz drive all-coherent charge transport and dynamical Bloch oscillations in bulk gallium selenide, leading to the emission of phase-stable, ultrashort and ultrabroadband optical pulses spanning the entire terahertz-to-visible spectral domain between 0.1 and 675 THz in a single waveform. Our experiments establish a new field of light-wave electronics exploring charge transport at optical clock rates. Furthermore, I will show how metamaterials can be used to achieve such extreme fields far beyond dc breakdown voltages at ever smaller THz frequencies, promising coherent charge transport under a quasi-static bias. THz-rate electric circuitry may soon be feasible at the interface of THz optics and electronics