Giant Second Harmonic Generation from Membrane Metasurfaces

Abstract

Metasurfaces have emerged as a fascinating framework for nonlinear optics, which have advantages of a compact footprint and unprecedented flexibility in manipulating light. But their nonlinear responses are generally limited by the short interaction lengths with light. Therefore, further enhancement is highly desired for building highefficiency nonlinear devices. Here, we experimentally demonstrate a record high second harmonic generation (SHG) efficiency of 2.0 × 10 −4 using lithium niobate (LN) membrane metasurfaces. Benefiting from the large refractive index contrast in the vertical direction and high fabrication quality, distinct spectral resonances and tight field confinements in the LN layer were achieved. Strong SHG peaks resulting from pump resonances of the metasurfaces were observed. Our nonlinear efficiency is more than 2 orders of magnitude larger than previously reported LN metasurfaces. The results inspire a way to improve the efficiency of nonlinear metasurfaces for ultracompact nonlinear light sources in applications of nonlinear holography, Li-Fi, beam shaping, etc.

Efficient second- and higher-order harmonic generation from LiNbO3 metasurfaces

“…The normalized efficiency of our LiNbO 3 metasurface is 5.1 × 10 −5 cm 2 GW −1 . We compare this value with other dielectric metasurfaces [36][37][38][39][40][41] including Si, 24,42,43 III-V semiconductors, 17,20,27,[44][45][46][47][48][49] and other LiNbO 3 platforms [50][51][52][53][54] and summarize the results in Fig. 4.…”

Optical Kerr nonlinearity of dielectric nanohole array metasurfaces with different hole shapes near anapole state

“…These membranes can be designed as hole arrays. For example, freestanding lithium niobate metasurfaces consisting of a square lattice of circular air holes experimentally demonstrated a high second harmonic generation efficiency in near-infrared range [14]. Primarily for perforated all-dielectric anapole metamaterials, grouped nanohole arrays were proposed [15].…”

Nonlinear and Emissive {[MIII(CN)6]3–···Polyresorcinol} (M = Fe, Co, Cr) Cocrystals Exhibiting an Ultralow Frequency Raman Response

“…This process relies on the interaction between matter and the incident beam, specifically, its polarization and orientation. The advantage of SHG lies in its narrow operating band, which allows for the precise control and manipulation of the generated signal. , The SHG function in the solid state requires a noncentrosymmetric space group and proper light absorption cutoff, which stimulated extended studies on the relevant inorganic, , organic, − as well as hybrid inorganic–organic − phases. In particular, the two latter composition strategies have recently been employed within the cocrystallization approach , considering the tunable intrinsic features of organic counterparts, e.g .…”