Terahertz shockwaves generated by a precise subcycle cut of the electric field

Johannes Bühler,Gabriel Fitzky,Daniele Brida,Jonas Allerbeck,Alfred Leitenstorfer

doi:10.1364/optica.5.000821

Abstract

Electromagnetic transients with a steep onset of the electric field represent the optical analog to acoustic shockwaves. Impulsive excitation of an electron-hole plasma with 8 fs pulses activates the reflection of high-field terahertz transients from a semiconductor surface on a deeply subcycle timescale. The resulting waveforms display a few-femtosecond rise of the electric field, equivalent to a broadening of their spectral content by several octaves. Such synthetic waveforms with subcycle shaping can be used, for example, as a tool to study extreme transport phenomena in condensed matter.

Highlights

Few-cycle optical pulses with high peak electric fields are versatile tools to investigate elementary processes at the ultrafast timescale [1,2,3,4,5,6,7,8]
To achieve ultrafast shaping of terahertz transients, we gate the reflectivity of a germanium (Ge) surface employed as an ultrafast active mirror [17]
A control pulse much shorter than one halfcycle of the terahertz field excites a dense electron-hole plasma, abruptly modifying the dielectric response of the semiconductor to behave like a metallic surface with high reflectivity

Summary

Introduction

Few-cycle optical pulses with high peak electric fields are versatile tools to investigate elementary processes at the ultrafast timescale [1,2,3,4,5,6,7,8]. Due to the short temporal resolution they offer, such single-cycle pulses at high optical frequencies seem to be an ideal tool for the study of processes occurring upon an impulsive change of the electric field.

Results

Conclusion