An Ultrafast Switchable Terahertz Polarization Modulator Based on III-V Semiconductor Nanowires.
Progress in the terahertz (THz) region of the electromagnetic spectrum is undergoing major advances, with advanced THz sources and detectors being developed at a rapid pace. Yet, ultrafast THz communication is still to be realized, owing to the lack of practical and effective THz modulators. Here, we present a novel ultrafast active THz polarization modulator based on GaAs semiconductor nanowires arranged in a wire-grid configuration. We utilize an optical pump-terahertz probe spectroscopy system and vary the polarization of the optical pump beam to demonstrate ultrafast THz modulation with a switching time of less than 5 ps and a modulation depth of -8 dB. We achieve an extinction of over 13% and a dynamic range of -9 dB, comparable to microsecond-switchable graphene- and metamaterial-based THz modulators, and surpassing the performance of optically switchable carbon nanotube THz polarizers. We show a broad bandwidth for THz modulation between 0.1 and 4 THz. Thus, this work presents the first THz modulator which combines not only a large modulation depth but also a broad bandwidth and picosecond time resolution for THz intensity and phase modulation, making it an ideal candidate for ultrafast THz communication.
Department of Engineering, University of Cambridge , 9 JJ Thomson Avenue, Cambridge CB3 0FA, United Kingdom.
Sarwat A
SA
Baig
Department of Physics, Clarendon Laboratory, University of Oxford , Parks Road, Oxford, OX1 3PU, United Kingdom.
Jessica L
JL
Boland
Department of Physics, Clarendon Laboratory, University of Oxford , Parks Road, Oxford, OX1 3PU, United Kingdom.
Djamshid A
DA
Damry
Department of Electronic Materials Engineering, Research School of Physics and Engineering, Australian National University , Canberra, Australian Capital Territory 2601, Australia.
H Hoe
HH
Tan
Department of Electronic Materials Engineering, Research School of Physics and Engineering, Australian National University , Canberra, Australian Capital Territory 2601, Australia.
Chennupati
C
Jagadish
Department of Engineering, University of Cambridge , 9 JJ Thomson Avenue, Cambridge CB3 0FA, United Kingdom.
Hannah J
0000-0002-9737-680X
HJ
Joyce
Department of Physics, Clarendon Laboratory, University of Oxford , Parks Road, Oxford, OX1 3PU, United Kingdom.
Michael B
0000-0002-0301-8033
MB
Johnston
GaAs; Terahertz (THz); modulator; nanowire; parylene; polarizer