Terahertz emission from lateral photo-Dember currents

  • The photo-Dember effect is a source of impulsive THz emission following femtosecond pulsed optical excitation. This emission results from the ultrafast spatial separation of electron-hole pairs in strong carrier gradients due to their different diffusion coefficients. The associated time dependent polarization is oriented perpendicular to the excited surface which is inaptly for efficient out coupling of THz radiation. We propose a scheme for generating strong carrier gradients parallel to the excited surface. The resulting photo-Dember currents are oriented in the same direction and emit THz radiation into the favorable direction perpendicular to the surface. This effect is demonstrated for GaAs and In(0.53)Ga(0.47)As. Surprisingly the photo-Dember THz emitters provide higher bandwidth than photoconductive emitters. Multiplexing of phase coherent photo-Dember currents by periodically tailoring the photoexcited spatial carrier distribution gives rise to a strongly enhanced THz emission, which reaches electric field amplitudes comparable to a high-efficiency externally biased photoconductive emitter.

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Author:Gregor Klatt, Florian Hilser, Wenchao Qiao, Matthias Beck, Raphael Gebs, Albrecht Bartels, Klaus Huska, Uli Lemmer, Georg Bastian, Michael B. Johnston, Milan Fischer, Jerome Faist, Thomas Dekorsy
Parent Title (English):Optics Express
Document Type:Article (specialist journals)
Date of OPUS upload:2022/09/21
Date of first Publication:2010/02/24
Publishing University:Hochschule Trier
Release Date:2022/09/21
Tag:including semiconductors; spectroscopy; terahertz; ultrafast processes in condensed matter
GND Keyword:Spektroskopie; Terahertzbereich
Article Number:PMID: 20389505
Page Number:9
First Page:4939
Last Page:4947
Departments:FB Technik
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 53 Physik
Licence (German):License LogoCreative Commons - CC BY - Namensnennung 4.0 International