Improved third-order nonlinear effect in graphene based on bound states in the continuum

Abstract

The scattering matrix theory has been developed to calculate the third-order nonlinear effect in sphere-grapheneslab structures. By designing structural parameters, we have demonstrated that the incident electromagnetic wave can be well confined in the graphene in these structures due to the formation of a bound state in the continuum (BIC) of radiation modes. Based on such a bound state, third-harmonic (TH) generation and four-wave mixing (FWM) have been studied. It is found that the efficiency of TH generation in monolayer graphene can be enhanced about 7 orders of magnitude. It is interesting that we can design structure parameters to make all beams (the pump beam, probe beam, and generated FWM signal) be BICs at the same time. In such a case, the efficiency of FWM in monolayer graphene can be enhanced about 9 orders of magnitude. Both the TH and FWM signals are sensitive to the wavelength, and possess high Q factors, which exhibit very good monochromaticity. By taking suitable BICs, the selective generation of TH and FWM signals for Sand P-polarized waves can also be realized, which is beneficial for the design of optical devices.

2D Layered Materials: Synthesis, Nonlinear Optical Properties, and Device Applications

“…These early works have greatly promoted the exploration of graphene-based nonlinear optics. [99][100][101][102][103][104] Based on the successful exploration of the nonlinear properties of graphene and its derivatives, researchers began to study other 2D materials, such as topological insulators, layered TMDCs, black phosphorus, and MXenes. Among them, topological insulators including Bi 2 Se 3 , Bi 2 Te 3 , and Sb 2 Te 3 , characterized by a robust metallic edge or surface state and a narrow band-gap bulk insulating state, have gained great attention in the field of physics, chemistry, and material.…”

All‐Inorganic Transparent Composite Materials for Optical Limiting

“…In recent years, low‐dimensional nonlinear materials have become a research hotspot. Various types of low‐dimensional nonlinear materials with improved nonlinear responses have been reported; these materials include TiS 2 layers,23 hexagonal BN nanosheets,24,25 graphene‐based materials,26–28 and 1D CdS29 and CdTe30 quantum dots. In addition, inorganic glass and their derived composites have attracted considerable interest as nonlinear optical limiting material candidates due to their stable chemical and physical properties 31–33.…”

Enhanced optical squeezing from quasi-bound states in the continuum and Fano resonances without nonlinearity

“…On the other hand, optical bound states in the continuum (BICs) in some nanostructures have attracted extensive attention from both theoretical and experimental sides in recent years [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41]. The BICs are known as embedded trapped modes, which correspond to discrete eigenvalues coexisting with extended modes of a continuous spectrum [42].…”

“…A true BICs is a mathematical object with an infinite value of the Q factor and vanishing resonance width, and it can exist only in ideal lossless structures [28][29][30]. In practice, BICs can be realized as a quasi-BICs, when both the Q factor and resonance width become finite [38][39][40][41]. Recent investigations have shown that the quasi-BICs with high-Q factor can be realized in some optical nanostructures [38][39][40][41].…”

“…In practice, BICs can be realized as a quasi-BICs, when both the Q factor and resonance width become finite [38][39][40][41]. Recent investigations have shown that the quasi-BICs with high-Q factor can be realized in some optical nanostructures [38][39][40][41]. In addition, Fano resonances, typically narrow line shapes that arise as the interference of a narrow dark resonance with a broad bright one [43][44][45], have also been the focus of attention.…”