Between photonics and electronics: 2D materials for THz technologies Alessandro Tredicucci1,2 1
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Dipartimento di Fisica “E. Fermi”, Università di Pisa, Largo Pontecorvo 3, 56127 Pisa (Italy) Laboratorio NEST, Istituto Nanoscienze – CNR and Scuola Normale Superiore, Piazza San Silvestro 12, 56127 Pisa (Italy)
Abstract— Its peculiar band structure and charge transport characteristics naturally suggest graphene could offer a perfect platform for a new generation of high-performance devices operating in the THz range of the electromagnetic spectrum. This talk will review recent results in the development of high-speed modulators and electronic detectors; it will also discuss perspectives towards the implementation of graphene-based deeply sub-wavelength THz emitters and lasers.
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RAPHENE is attracting considerable attention for a variety of photonic applications, including fast photodetectors, transparent electrodes in displays and photovoltaic modules, saturable absorbers. Owing to its high carrier mobility, gapless spectrum, tuneable chemical potential, and frequencyindependent absorption coefficient, it has been recognized as a very promising element for the development of detectors and modulators operating in the Terahertz (THz) region of the electromagnetic spectrum, which is still crucially lacking in terms of solid-state devices [1]. In the last few years, progress in the realization of graphene-based THz photonic devices has advanced very rapidly. In this talk I will focus first THz detectors based on antenna-coupled graphene field-effect transistors (FETs) [2,3,4], discuss the various mechanisms involved in their operation, and examine extension to other 2D materials and integration into future THz cameras. I will also address the development and applications of electrically switchable metamaterial devices [5] as well as the prospects for the use of graphene in a new generation of THz sources, either directly as active element [6], or as waveguide optical component. In the latter case, graphene could be implemented within quantum cascade lasers and act as saturable absorber for mode-locked operation [7], or even replace one of the metal layers in micro-disk resonators, yielding a huge reduction in size and possibly approaching a thresholdless lasing regime. Finally, schemes to implement coherent control of absorption in graphene will be analysed [8], as well as perspectives of observing few-electrons intersubband THz polaritons in extremely subwavelength graphene microcavities, opening a path for implementing novel forms of photon-photon interactions and for realizing complex, purely photonic quantum devices.
REFERENCES [1] A. Tredicucci, M.S. Vitiello, IEEE J. Sel. Top. Quantum Electron. 20, 130 (2014). [2] L. Vicarelli, M.S. Vitiello, D. Coquillat, A. Lombardo, A.C. Ferrari, W. Knap, M. Polini, V. Pellegrini, A. Tredicucci, Nat. Mater. 11, 856 (2012).
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[3] A.A. Generalov, M.A. Andersson, X. Yang, A. Vorobiev , J. Stake, IEEE Trans. Terahertz Sci. Technol. 7, 614 (2017). [4] D.A. Bandurin, et al., Nat. Commun. 9, 5392 (2018). [5] R. Degl'Innocenti, S.J. Kindness, H.E. Beere, D.A. Ritchie, Nanophotonics 7, 127 (2018). [6] D. Yadav, et al., Nanophotonics 7, 741 (2018). [7] V. Bianchi, T. Carey, L. Viti, L. Li, E.H. Linfield, A.G. Davies, A. Tredicucci, D. Yoon, P.G. Karagiannidis, L. Lombardi, F. Tomarchio, A.C. Ferrari, F. Torrisi, M.S. Vitiello, Nat. Commun. 8, 15763 (2017). [8] S. Zanotto, F. Bianco, V. Miseikis, D. Convertino, C. Coletti, A. Tredicucci, APL Photonics 2, 016101 (2017)..
