Resonantly enhanced second-and third-harmonic generation in dielectric nonlinear metasurfaces  

作　　者：Ji Tong Wang Pavel Tonkaev Kirill Koshelev Fangxing Lai Sergey Kruk Qinghai Song Yuri Kivshar Nicolae C.Panoiu 

机构地区：[1]Department of Electronic and Electrical Engineering,University College London,London WC1E 7JE,United Kingdom [2]Nonlinear Physics Center,Research School of Physics,Australian National University,Canberra ACT 2601,Australia [3]Ministry of Industry and Information Technology Key Lab of Micro-Nano Optoelectronic Information System,Guangdong Provincial Key Laboratory of Semiconductor Optoelectronic Materials and Intelligent Photonic Systems,Harbin Institute of Technology,Shenzhen 518055,China [4]Wuzhen Laboratory,EGO Wuzhen Digital Economy Industrial Park,No.925 Daole Road,Tongxiang,China

出　　处：《Opto-Electronic Advances》2024年第5期5-19,共15页光电进展（英文）

基　　金：supported by the Australian Research Council(Grant No.DP210101292);the International Technology Center Indo-Pacific (ITC IPAC) via Army Research Office (contract FA520923C0023)。

摘　　要：Nonlinear dielectric metasurfaces provide a promising approach to control and manipulate frequency conversion optical processes at the nanoscale,thus facilitating both advances in fundamental research and the development of new practical applications in photonics,lasing,and sensing.Here,we employ symmetry-broken metasurfaces made of centrosymmetric amorphous silicon for resonantly enhanced second-and third-order nonlinear optical response.Exploiting the rich physics of optical quasi-bound states in the continuum and guided mode resonances,we comprehensively study through rigorous numerical calculations the relative contribution of surface and bulk effects to second-harmonic generation(SHG)and the bulk contribution to third-harmonic generation(THG) from the meta-atoms.Next,we experimentally achieve optical resonances with high quality factors,which greatly boosts light-matter interaction,resulting in about 550 times SHG enhancement and nearly 5000-fold increase of THG.A good agreement between theoretical predictions and experimental measurements is observed.To gain deeper insights into the physics of the investigated nonlinear optical processes,we further numerically study the relation between nonlinear emission and the structural asymmetry of the metasurface and reveal that the generated harmonic signals arising from linear sharp resonances are highly dependent on the asymmetry of the meta-atoms.Our work suggests a fruitful strategy to enhance the harmonic generation and effectively control different orders of harmonics in all-dielectric metasurfaces,enabling the development of efficient active photonic nanodevices.

关 键 词：second-harmonic generation third-harmonic generation bound state in the continuum guided mode resonance all-dielectric metasurfaces nonlinear optics 

分 类 号：O437[机械工程—光学工程]