Fast terahertz optoelectronic amplitude modulator based on plasmonic metamaterial antenna arrays and graphene

Jessop, David S. and Sol, Christian W. O. and Xiao, Long and Kindness, Stephen J. and Braeuninger-Weimer, Philipp and Lin, Hungyen and Griffiths, Jonathan P. and Ren, Yuan and Kamboj, Varun S. and Hofmann, Stephan and Zeitler, J. Axel and Beere, Harvey E. and Ritchie, David A. and Degl'innocenti, Riccardo (2016) Fast terahertz optoelectronic amplitude modulator based on plasmonic metamaterial antenna arrays and graphene. Proceedings of SPIE, 9747. ISSN 0277-786X

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The growing interest in terahertz (THz) technologies in recent years has seen a wide range of demonstrated applications, spanning from security screening, non-destructive testing, gas sensing, to biomedical imaging and communication. Communication with THz radiation offers the advantage of much higher bandwidths than currently available, in an unallocated spectrum. For this to be realized, optoelectronic components capable of manipulating THz radiation at high speeds and high signal-to-noise ratios must be developed. In this work we demonstrate a room temperature frequency dependent optoelectronic amplitude modulator working at around 2 THz, which incorporates graphene as the tuning medium. The architecture of the modulator is an array of plasmonic dipole antennas surrounded by graphene. By electrostatically doping the graphene via a back gate electrode, the reflection characteristics of the modulator are modified. The modulator is electrically characterized to determine the graphene conductivity and optically characterization, by THz time-domain spectroscopy and a single-mode 2 THz quantum cascade laser, to determine the optical modulation depth and cut-off frequency. A maximum optical modulation depth of ~ 30% is estimated and is found to be most (least) sensitive when the electrical modulation is centered at the point of maximum (minimum) differential resistivity of the graphene. A 3 dB cut-off frequency > 5 MHz, limited only by the area of graphene on the device, is reported. The results agree well with theoretical calculations and numerical simulations, and demonstrate the first steps towards ultra-fast, graphene based THz optoelectronic devices. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

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Proceedings of SPIE
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05 Aug 2016 15:26
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17 Sep 2023 01:52