Extreme nonlinear terahertz electro-optics in diamond for ultrafast pulse switching

Abstract

Polarization switching of picosecond laser pulses is a fundamental concept in signal processing [C. Chen and G. Liu, Annu. Rev. Mater. Sci. 16, 203 (1986); V. R. Almeida et al., Nature 431, 1081 (2004); and A. A. P. Pohl et al., Photonics Sens. 3, 1 (2013)]. Conventional switching devices rely on the electro-optical Pockels effect and work at radio frequencies. The ensuing gating time of several nanoseconds is a bottleneck for faster switches which is set by the performance of state-of-the-art high-voltage electronics. Here we show that by substituting the electric field of several kV/cm provided by modern electronics by the MV/cm field of a single-cycle THz laser pulse, the electro-optical gating process can be driven orders of magnitude faster, at THz frequencies. In this context, we introduce diamond as an exceptional electro-optical material and demonstrate a pulse gating time as fast as 100 fs using sub-cycle THz-induced Kerr nonlinearity. We show that THz-induced switching in the insulator diamond is fully governed by the THz pulse shape. The presented THz-based electro-optical approach overcomes the bandwidth and switching speed limits of conventional MHz/GHz electronics and establishes the ultrafast electro-optical gating technology for the first time in the THz frequency range. We finally show that the presented THz polarization gating technique is applicable for advanced beam diagnostics. As a first example, we demonstrate tomographic reconstruction of a THz pulse in three dimensions.

Organic Crystals for THz Photonics

“…The observable high increase in the transmission of n-doped silicon in the THz range by almost two orders can lead to the development of novel THz absorbers and THz field controlled electronic devices [161]. An ultrafast THz-induced optical modulator for pulse switching in a thin diamond window has also been demonstrated [193].…”

Attenuation of THz Beams: A “How to” Tutorial

“…Technological developments in the past years has made it possible to use commercial table-top femtosecond laser systems to generate intense, ultrashort THz pulses in the 0.1-5-THz range with focused field strengths in the megavolt/centimeter range, and pulse energies from microjoules towards millijoules and beyond from inorganic and organic nonlinear crystals [1][2][3]. Such coherent THz pulses are used to investigate nonlinear interactions between strong, ultrafast THz fields and virtually all material types, including a few examples of studies of dielectrics [4][5][6], semiconductors, metals [7,8], magnetic materials [9], 2D materials [10], liquids [11,12], and gases [13].…”

Ultrafast Electron Dynamics in Magnetic Thin Films

“…This results in a set of pulses that are well defined in spectral content, we expect these pulses to contain several oscillation pulses in the time domain. To further characterise the pulses, we refer to a previous work on the same THz source: [27]. In the cited text, a one-to-one correspondence between the pulse fluence and the peak electric field strength was found through the Kerr effect in diamond, allowing us to infer the fluence of a filtered pulse by measuring the pulse duration and spot size (measured previously in [28]).…”