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HL: Fachverband Halbleiterphysik

HL 8: Ultrafast Phenomena I

HL 8.6: Vortrag

Montag, 18. März 2024, 16:30–16:45, EW 015

Ultrahigh-Sensitive Optical Detection of Coherent Acoustic Phonons in a GaAs/GaAlAs Superlattice — •Marek Karzel¹, Anton Samusev¹, Alexey V. Scherbakov¹, Tetiana Linnik¹, Mario Littmann², Andrey V. Akimov³, Dirk Reuter², and Manfred Bayer¹ — ¹Technische Universität Dortmund, 44227 Dortmund, Germany — ²Universität Paderborn, 33098 Paderborn, Germany — ³University of Nottingham, NG7 2RD Nottingham, United Kingdom

The optical detection of coherent acoustic phonons is a primary tool in ultrafast acoustics. It engages the application of phonons in quantum technology, which is especially promising for nanoscale communications. The ultrahigh-sensitive detection of optically generated phonons with frequencies above 20  GHz can be accomplished due to optical probing in the spectral vicinity of polariton resonance, where a strong permittivity dispersion is observed [1, 2]. In this work, we monitor the propagation of the optically generated coherent phonon wave packet in a semiconductor superlattice of GaAs/Ga_0.67Al_0.33As at a temperature of 10  K. With the experimental scheme, we achieve a remarkably high detection sensitivity confirmed by probing coherent acoustic wave packets with less than (on average) one phonon within the bandwidth of interest. The lattice strain induced by such a weak elastic perturbation is of an order of 10⁻⁹ with the corresponding lattice displacement of only ≈ 10⁻¹⁶  m.

[1] A. N. Poddubny, et al., Phys. Rev. B 89, 235313 (2014).

[2] M. Kobecki, et al., Phys. Rev. Lett. 128, 157401 (2022).

Keywords: acoustic phonons; polaritons; photoelastic effect; pump-probe spectroscopy; superlattice