Tailoring Third-Harmonic Diffraction Efficiency by Hybrid Modes in High-Q Metasurfaces

Abstract

Metasurfaces are versatile tools for manipulating light; however, they have received little attention as devices for the efficient control of nonlinearly diffracted light. Here, we demonstrate nonlinear wavefront control through third-harmonic generation (THG) beaming into diffraction orders with efficiency tuned by excitation of hybrid Mie–quasi-bound states in the continuum (BIC) modes in a silicon metasurface. Simultaneous excitation of the high-Q collective Mie-type modes and quasi-BIC modes leads to their hybridization and results in a local electric field redistribution. We probe the hybrid mode by measuring far-field patterns of THG and observe the strong switching between (0,–1) and (−1,0) THG diffraction orders from 1:6 for off-resonant excitation to 129:1 for the hybrid mode excitation, showing tremendous contrast in controlling the nonlinear diffraction patterns. Our results pave the way to the realization of metasurfaces for novel light sources, telecommunications, and quantum photonics.

Photonic spin-selective perfect absorptance on planar metasurfaces driven by chiral quasi-bound states in the continuum

“…So far, assisted by the physics of chiral Q-BIC and the single-port critical coupling, the chiral perfect absorber with tunable spin selectivity is successfully realized. The established planar microfabrication techniques, [76][77][78] such as the electron beam lithography companied by the processes of deposition, patterning, lift-off, and etching, are competent for the construction of such planar silicon metasurface. The robustness of the chiral perfect absorptance is also investigated via changing the structural parameters including W 1 , L 1 , H, and a.…”

Fully Integrated Silicon Photonic Erbium-Doped Nanodiode for Few Photon Emission at Telecom Wavelengths

“…The entire process is performed on a 220 nm-thick Si layer on a 3 µm-thick SiO buried oxide layer ( Figure 1 a). The first step is the definition of the mesa structure by electron beam lithography and reactive ion etching ( Figure 1 b) [ 22 , 23 ]. Next, dopants are introduced by ion implantation and activated through a rapid thermal annealing process ( Figure 1 c).…”

Recent advances in strongly resonant and gradient all-dielectric metasurfaces

“…graphene plasmons with a very short propagation wavelength can help avoid this, if so desired 74 .) Thus, the diffraction efficiency/directionality of the emitted THG wave can be controlled, e.g., by engineering the hybridization between Mie and qBIC modes as recently demonstrated 66 . In particular, by switching the angle of incidence of the pump laser beam the distribution of the THG wave among the various diffraction orders is significantly modified, as shown in Fig.…”

“…, by engineering the hybridization between Mie and qBIC modes as recently demonstrated. 66 In particular, by switching the angle of incidence of the pump laser beam the distribution of the THG wave among the various diffraction orders is significantly modified, as shown in Fig. 2(a).…”