Acoustic band engineering in terahertz quantum-cascade lasers and arbitrary superlattices

Demić, Aleksandar; Valavanis, Alexander; Dean, Paul; Li, Lianhe; Davies, A. Giles; Linfield, Edmund H.; Cunningham, John; Bailey, James; Akimov, Andrey; Kent, Anthony; Harrison, Paul

Abstract

We present theoretical methods for the analysis of acoustic phonon modes in superlattice structures, and terahertz-frequency quantum-cascade lasers (THz QCLs). Our generalized numerical solution of the acoustic-wave equation provides good agreement with experimental pump-probe measurements of the acoustic resonances in a THz QCL. We predict that the detailed layer structure in THz QCLs imprints up to ∼2GHz detuning of the acoustic mode spacing, which cannot be seen in analytical models. This effect is strongest in devices with large and abrupt acoustic mismatch between layers. We use an acoustic deformation potential within a density-matrix approach to analyze electron transport induced in a range of the most common THz QCL active-region design schemes. We conclude that acoustic modes up to ∼200GHz are capable of significantly perturbing QCL transport, highlighting their potential for ultrafast modulation of laser emission.

Citation

Demić, A., Valavanis, A., Dean, P., Li, L., Davies, A. G., Linfield, E. H., …Harrison, P. (2023). Acoustic band engineering in terahertz quantum-cascade lasers and arbitrary superlattices. Physical Review B, 107(23), Article 235411. https://doi.org/10.1103/physrevb.107.235411

• Journal Article Type: Article
• Acceptance Date: May 19, 2023
• Online Publication Date: Jun 14, 2023
• Publication Date: Jun 15, 2023
• Deposit Date: Jun 22, 2023
• Publicly Available Date: Jun 23, 2023
• Journal: Physical Review B
• Print ISSN: 2469-9950
• Electronic ISSN: 2469-9969
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 107
• Issue: 23
• Article Number: 235411
• DOI: https://doi.org/10.1103/physrevb.107.235411
• Keywords: Acoustic phonons; Phonons; Quantum cascade lasers
• Public URL: https://nottingham-repository.worktribe.com/output/21917351
• Publisher URL: https://journals.aps.org/prb/abstract/10.1103/PhysRevB.107.235411