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Fast Modulation of Terahertz Quantum Cascade Lasers Using Graphene Loaded Plasmonic Antennas

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Degl'innocenti, R 
Jessop, DS 
Sol, CWO 
Xiao, L 
Kindness, SJ 


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 modulator’s 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 cutoff 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.



terahertz optical modulator, graphene, plasmonic antennas, quantum cascade lasers

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ACS Photonics

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American Chemical Society (ACS)
Engineering and Physical Sciences Research Council (EP/K016636/1)
Engineering and Physical Sciences Research Council (EP/L019922/1)
Engineering and Physical Sciences Research Council (EP/J017671/1)
RD, YR and HEB acknowledge financial support from the Engineering and Physical Sciences Research Council (Grant No. EP/J017671/1, Coherent Terahertz Systems). HL and JAZ would like to acknowledge the financial support from UK EPSRC Research Grant EP/L019922/1.