摘要
Bound-states-in-the-continuum(BIC)is an emerging concept in nanophotonics with potential impact in applications,such as hyperspectral imaging,mirror-less lasing,and nonlinear harmonic generation.As true BIC modes are nonradiative,they cannot be excited by using propagating light to investigate their optical characteristics.In this paper,for the 1st time,we map out the strong near-field localization of the true BIC resonance on arrays of silicon nanoantennas,via electron energy loss spectroscopy with a sub-1-nm electron beam.By systematically breaking the designed antenna symmetry,emissive quasi-BIC resonances become visible.This gives a unique experimental tool to determine the coherent interaction length,which we show to require at least six neighboring antenna elements.More importantly,we demonstrate that quasi-BIC resonances are able to enhance localized light emission via the Purcell effect by at least 60 times,as compared to unpatterned silicon.This work is expected to enable practical applications of designed,ultra-compact BIC antennas such as for the controlled,localized excitation of quantum emitters.
基金
The authors would like to acknowledge the funding support from Agency for Science,Technology and Research(A*STAR)SERC Pharos project(grant number 1527300025)
In addition,Z.D.and J.K.W.Y.would like to acknowledge the A*STAR AME IRG funding support with the project number A20E5c0093
Z.D.acknowledges support from A*STAR career development award(CDA)with the grant number 202D8088
M.B.acknowledges support from the Singapore Ministry of Education Academic Research Fund Tier 2(project number MOE2019-T2-1-179)
A.I.F.D.was supported by a 2019 Leonardo Grant for Researchers and Cultural Creators,BBVA Foundation
Z.M.acknowledges support from the European Union’s Horizon 2020 research and innovation program under grant agreement No 823717–ESTEEM3
J.K.W.Y.would like to acknowledge the funding from National Research Foundation(NRF)Singapore with the grant numbers NRF-CRP20-2017-0001 and NRF-NRFI06-2020-0005.
