In photonic structures,bound states in the continuum(BICs)have recently attracted huge interest in both fundamental and applied research.Quasi-BIC leaky modes resulting from in-plane symmetry breaking in metasurfaces ...In photonic structures,bound states in the continuum(BICs)have recently attracted huge interest in both fundamental and applied research.Quasi-BIC leaky modes resulting from in-plane symmetry breaking in metasurfaces are particularly relevant to applications,due to their high quality factor,which scales as the squared inverse of the asymmetry parameter.Here,we theoretically propose an innovative approach to switch on quasi-BICs on sub-picosecond timescales via optically induced symmetry breaking in semiconductor metasurfaces.The desired effect is granted by exploiting the spatial inhomogeneities in the distribution of photo-excited hot carriers at the single meta-atom nanometric scale.In our simulations,the quasi-BIC state manifests itself as an ultra-sharp dip in transmission,emerging upon pump arrival,and disappearing completely within the carriers'diffusion timescale.Our strategy allows to envision reconfigurable platforms with switchable high-Q resonances,with ultrafast recovery beyond the limits of carrier relaxation,typical of previous approaches.展开更多
Switching of light polarization on the sub-picosecond timescale is a crucial functionality for applications in a variety of contexts,including telecommunications,biology and chemistry.The ability to control polarizati...Switching of light polarization on the sub-picosecond timescale is a crucial functionality for applications in a variety of contexts,including telecommunications,biology and chemistry.The ability to control polarization at ultrafast speed would pave the way for the development of unprecedented free-space optical links and of novel techniques for probing dynamical processes in complex systems,as chiral molecules.Such high switching speeds can only be reached with an all-optical paradigm,i.e.,engineering active platforms capable of controlling light polarization via ultrashort laser pulses.Here we demonstrate giant modulation of dichroism and birefringence in an all-dielectric metasurface,achieved at low fluences of the optical control beam.This performance,which leverages the many degrees of freedom offered by all-dielectric active metasurfaces,is obtained by combining a high-quality factor nonlocal resonance with the giant third-order optical nonlinearity dictated by photogenerated hot carriers at the semiconductor band edge.展开更多
基金funding from the European Union Horizon 2020 Research and Innovation programme under grant agreement no.899673G.D.V.acknowledges the support from the HOTMETA project under the PRIN 2022 MUR programme funded by the European Union-Next Generation EU-“PNRR-M4C2,investimento 1.1-“Fondo PRIN 2022”-HOT-carrier METasurfaces for Advanced photonics(HOTMETA),contract no.2022LENW33-CUP:D53D23002290006”+3 种基金by the European Union’s NextGenerationEU Programme with the I-PHOQS Infrastructure[IR0000016,ID D2B8D520,CUPB53C22001750006]“Integrated infrastructure initiative in Photonic and Quantum Sciences”A.S.and G.D.V.acknowledge financial support from the European Union’s Horizon Europe research and innovation programme under the Marie Skaodowska-Curie Action PATHWAYS HORIZON-MSCA-2023-PF-GF grant agreement no.101153856G.C.acknowledges financial support from the ERC-StG ULYSSES grant agreement no.101077181 funded by the European Unionsupported by the Federal Academic Leadership Program Priority 2030.
文摘In photonic structures,bound states in the continuum(BICs)have recently attracted huge interest in both fundamental and applied research.Quasi-BIC leaky modes resulting from in-plane symmetry breaking in metasurfaces are particularly relevant to applications,due to their high quality factor,which scales as the squared inverse of the asymmetry parameter.Here,we theoretically propose an innovative approach to switch on quasi-BICs on sub-picosecond timescales via optically induced symmetry breaking in semiconductor metasurfaces.The desired effect is granted by exploiting the spatial inhomogeneities in the distribution of photo-excited hot carriers at the single meta-atom nanometric scale.In our simulations,the quasi-BIC state manifests itself as an ultra-sharp dip in transmission,emerging upon pump arrival,and disappearing completely within the carriers'diffusion timescale.Our strategy allows to envision reconfigurable platforms with switchable high-Q resonances,with ultrafast recovery beyond the limits of carrier relaxation,typical of previous approaches.
基金funding from the European Union Horizon 2020 Research and Innovation program under grant agreement no.899673This work reflects only authors’view and the European Commission is not responsible for any use that may be made of the information it contains.G.D.V.acknowledges the support from the HOTMETA project under the PRIN 2022 MUR program funded by the European Union—Next Generation EU—“PNRR-M4C2,investimento 1.1—“Fondo PRIN 2022”—HOT-carrier METasurfaces for Advanced photonics(HOTMETA)+1 种基金contract no.2022LENW33—CUP:D53D23002290006”.A.S.,G.C.,M.M.and G.D.V.acknowledge financial support by the European Union’s NextGenerationEU Programme with the I-PHOQS Infrastructure[IR0000016,ID D2B8D520,CUP B53C22001750006]“Integrated infrastructure initiative in Photonic and Quantum Sciences”.The work is partly supported by the French RENATECH networksupport by the European Union-NextGenerationEU,through the National Recovery and Resilience Plan of the Republic of Bulgaria,SUMMIT BG-RRP-2.004-0008-C0.DN acknowledges the support of the Australian Research Council(CE200100010).
文摘Switching of light polarization on the sub-picosecond timescale is a crucial functionality for applications in a variety of contexts,including telecommunications,biology and chemistry.The ability to control polarization at ultrafast speed would pave the way for the development of unprecedented free-space optical links and of novel techniques for probing dynamical processes in complex systems,as chiral molecules.Such high switching speeds can only be reached with an all-optical paradigm,i.e.,engineering active platforms capable of controlling light polarization via ultrashort laser pulses.Here we demonstrate giant modulation of dichroism and birefringence in an all-dielectric metasurface,achieved at low fluences of the optical control beam.This performance,which leverages the many degrees of freedom offered by all-dielectric active metasurfaces,is obtained by combining a high-quality factor nonlocal resonance with the giant third-order optical nonlinearity dictated by photogenerated hot carriers at the semiconductor band edge.
