Regensburg 2022 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 40: THz and MIR Physics in Semiconductors
HL 40.1: Vortrag
Freitag, 9. September 2022, 09:30–09:45, H33
Generation of intense sub-half-cycle terahertz pulses from spatially indirect interband transitions — •Christian Meineke1, Michael Prager1, Johannes Hayes1, Qiannan Wen2, Lukas Kastner1, Dieter Schuh1, Kilian Fritsch3, Oleg Pronin3, Markus Stein4, Sangam Chatterjee4, Mackillo Kira2, Rupert Huber1, and Dominique Bougeard1 — 1University of Regensburg, 93040 Regensburg — 2University of Michigan, Ann Arbor, Mi 48109 — 3Helmut Schmidt University, 22043 Hamburg — 4Justus Liebig University, 35392 Giessen
Ultimately short phase-stable terahertz (THz) pulses form the bedrock of THz lightwave electronics, where the carrier field creates a transient bias to control electrons on sub-cycle time scales. Here, we introduce a fully scalable high-repetition-rate THz source generating intense phase-locked and strongly asymmetric sub-cycle field transients. The key idea is to engineer electronic wavefunctions in type-II aligned semiconductor quantum wells such that resonant interband photoexcitation induces an ultrafast charge separation over several nanometers even without any bias. Our detailed quantum mechanical analysis reveals that local charging dynamics lifts the spatial separation of electrons and holes, leading to an abrupt decrease of the dipole moment, generating one single pronounced positive field peak. The THz bandwidth is scalable up to the mid-infrared by reducing the pump pulse duration. The versatility of our emitter allows adjusting waveforms, spectra, and field strengths to many applications, such as ultrabroadband spectroscopy and femtosecond nanoscopy.