An ultrafast switchable terahertz polarization modulator based on III--V semiconductor nanowires

Journal article

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 realised, 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 utilise 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 -8dB. We achieve extinction of over 13% and dynamic range of -9dB, 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 0.1THz and 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.

Authors: Baig, S; Boland, J; Damry, D; Tan, H; Jagadish, C

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Chemical Society
• Journal: Nano Letters
• Volume: 17
• Issue: 4
• Pages: 2603–2610
• Publication date: 2017-01-01
• Acceptance date: 2017-03-23
• DOI: 10.1021/acs.nanolett.7b00401
• ISSN: 1530-6992
• Keywords: polarizer; modulator; GaAs; nanowire; Terahertz (THz); parylene