Abstract-Fast modulation of terahertz quantum cascade lasers using graphene loaded plasmonic antennas

Riccardo Degl'Innocenti, David S. Jessop, Christian W. O. Sol, Long Xiao, Stephen J. Kindness, Hungyen Lin, J. Axel Zeitler, Philipp Braeuninger-Weimer, Stephan Hofmann, Yuan Ren, Varun S. Kamboj, Jonathan P. Griffiths, Harvey E. Beere, and David A. Ritchie

ACS Photonics, Just Accepted Manuscript

DOI: 10.1021/acsphotonics.5b00672

Publication Date (Web): February 23, 2016

Copyright © 2016 American Chemical Society

http://pubs.acs.org/doi/abs/10.1021/acsphotonics.5b00672?journalCode=apchd5

We report the fast amplitude modulation of a quantum cascade laser emitting in single mode operation in the terahertz frequency range by employing compact, integrated devices based on the interplay between plasmonic antenna arrays and monolayer graphene. By acting on the carrier concentration of graphene the optical response of these plasmonic resonances was modified. The modulators characteristics have been studied by using both time domain spectroscopic laser systems, yielding the broad frequency response of these resonant arrays, and quantum cascade lasers, providing us with a narrow and stable laser source, a mandatory prerequisite for the determination of the modulation speed of these devices. The measured modulation speed exhibits a cut-off frequency of 5.5 MHz ± 1.1 MHz. These results represent the first step toward the realization of fast integrated circuitry for communications in the terahertz frequency range.