High-speed modulation of a terahertz quantum cascade laser by coherent acoustic phonon pulses

Dunn, Aniela; Poyser, Caroline; Dean, Paul; Demi?, Aleksandar; Valavanis, Alexander; Indjin, Dragan; Salih, Mohammed; Kundu, Iman; Li, Lianhe; Akimov, Andrey; Davies, Alexander Giles; Linfield, Edmund; Cunningham, John; Kent, Anthony

Abstract

The fast modulation of lasers is a fundamental requirement for applications in optical communications, high-resolution spectroscopy and metrology. In the terahertz-frequency range, the quantum-cascade laser (QCL) is a high-power source with the potential for high-frequency modulation. However, conventional electronic modulation is limited fundamentally by parasitic device impedance, and so alternative physical processes must be exploited to modulate the QCL gain on ultrafast timescales. Here, we demonstrate an alternative mechanism to modulate the emission from a QCL device, whereby optically-generated acoustic phonon pulses are used to perturb the QCL bandstructure, enabling fast amplitude modulation that can be controlled using the QCL drive current or strain pulse amplitude, to a maximum modulation depth of 6% in our experiment. We show that this modulation can be explained using perturbation theory analysis. While the modulation rise-time was limited to ~800 ps by our measurement system, theoretical considerations suggest considerably faster modulation could be possible.

Citation

Dunn, A., Poyser, C., Dean, P., Demić, A., Valavanis, A., Indjin, D., Salih, M., Kundu, I., Li, L., Akimov, A., Davies, A. G., Linfield, E., Cunningham, J., & Kent, A. (2020). High-speed modulation of a terahertz quantum cascade laser by coherent acoustic phonon pulses. Nature Communications, 11, Article 835. https://doi.org/10.1038/s41467-020-14662-w

• Journal Article Type: Article
• Acceptance Date: Jan 23, 2020
• Online Publication Date: Feb 11, 2020
• Publication Date: Feb 11, 2020
• Deposit Date: Jan 26, 2020
• Publicly Available Date: Feb 17, 2020
• Journal: Nature Communications
• Electronic ISSN: 2041-1723
• Publisher: Nature Publishing Group
• Peer Reviewed: Peer Reviewed
• Volume: 11
• Article Number: 835
• DOI: https://doi.org/10.1038/s41467-020-14662-w
• Keywords: General Biochemistry, Genetics and Molecular Biology; General Physics and Astronomy; General Chemistry
• Public URL: https://nottingham-repository.worktribe.com/output/3807618
• Publisher URL: https://www.nature.com/articles/s41467-020-14662-w
• Additional Information: Received: 15 August 2019; Accepted: 23 January 2020; First Online: 11 February 2020; : The authors declare no competing interests.