Show simple item record

dc.contributor.authorTunesi, J.
dc.contributor.authorPeters, L.
dc.contributor.authorGongora, J. S. Totero
dc.contributor.authorPasquazi, A.
dc.contributor.authorFratalocchi, Andrea
dc.contributor.authorPeccianti, M.
dc.date.accessioned2019-12-08T08:52:06Z
dc.date.available2019-12-08T08:52:06Z
dc.date.issued2019-10-17
dc.identifier.citationTunesi, J., Peters, L., Gongora, J. S. T., Pasquazi, A., Fratalocchi, A., & Peccianti, M. (2019). Optically-Induced Dynamic Terahertz Metamaterials. 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC). doi:10.1109/cleoe-eqec.2019.8872484
dc.identifier.doi10.1109/CLEOE-EQEC.2019.8872484
dc.identifier.urihttp://hdl.handle.net/10754/660442
dc.description.abstractSummary form only given. Plasmonic metasurfaces provide a compact platform to engineer the wave-front of optical beams by tuning the material and its morphology, hence enabling advanced functionalities in ultra-thin photonic systems. In standard metasurfaces, however, the optical response is usually static and fixed by design. An appealing possibility to achieve ultrafast dynamical tuning is given by optically-induced plasmonic systems, where the metallic response of narrow-bandgap semiconductors is driven by high-fluence illumination. Under these conditions, the surface of the semiconductor can be overflown with photo-carriers inducing a transient metallic state. An intriguing question is whether the transient metallization could be employed to dynamically engineer the optical response and to control light-matter interactions on the surface. At THz frequency-scales an optically-induced metallisation can have an initial transient much faster than the THz-period. The generation of THz fields from semiconductor surfaces is in fact, the result of a complex interplay between photo-carrier dynamics (e.g. photo-Dember) and nonlinear frequency conversion (e.g. optical rectification). A detailed characterization of the THz emission, therefore, can provide critical insights into the dynamical evolution and physical properties of the photo-induced plasmonic state. In this work, we will discuss our investigation of the THz emission from nanostructured silicon surfaces which are characterised by a near-unity absorption across the visible spectral range and are commonly denoted as Black Silicon (BSi). In BSi, the surface nanopatterning is known to induce a strong enhancement of the THz generation under ultrafast illumination, in sharp contrast with planar silicon where optical-to-THz conversion is mostly negligible. The generation of THz pulses from BSi however, is indeed driven by the presence of several competing mechanisms, including transient metallization and charge localization. We assessed the role played by each of these mechanisms through an embodiment of a dual pump approach. In our experimental setup, an ultrashort probe pulse generates THz within the sample to be detected, while a pump pulse photo-excites the nanopillars to induce the transient metallic state. The use of two optical pulses ensures significant overlap between the generated carriers and the THz generation region. For BSi, we observe a sharp transition between several regimes as a function of pump delay, with the emergence of an additional THz generation process upon photoexcitation, compatible with a plasmonic coupling and thus resulting in the observed phase shift. These results hold significant implications for a tuneable plasmonic response controlled via external pumping parameters with applications in nonlinear imaging.
dc.publisherIEEE
dc.relation.urlhttps://ieeexplore.ieee.org/document/8872484/
dc.relation.urlhttps://ieeexplore.ieee.org/document/8872484/
dc.relation.urlhttps://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=8872484
dc.rightsArchived with thanks to IEEE
dc.titleOptically-Induced Dynamic Terahertz Metamaterials
dc.typeConference Paper
dc.contributor.departmentEmergent Photonics Lab (EPic), Dept. of Physics and Astronomy, University of Sussex, BN1 9QH, UK; PRIMALIGHT, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
dc.contributor.departmentElectrical Engineering Program
dc.contributor.departmentComputer, Electrical and Mathematical Sciences and Engineering (CEMSE) Division
dc.conference.date23-27 June 2019
dc.conference.name2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)
dc.conference.locationMunich, Germany
dc.eprint.versionPost-print
kaust.personTunesi, J.
kaust.personPeters, L.
kaust.personGongora, J. S. Totero
kaust.personGongora, J. S. Totero
kaust.personPasquazi, A.
kaust.personFratalocchi, Andrea
kaust.personPeccianti, M.
dc.date.published-online2019-10-17
dc.date.published-print2019-06


This item appears in the following Collection(s)

Show simple item record