Third-Order Optical Nonlinearity in Two-Dimensional Transition Metal Dichalcogenides

Abstract

We present a detailed calculation of the linear and nonlinear optical response of four types of monolayer two-dimensional (2D) transition-metal dichalcogenides (TMDCs), having the formula MX2 with M=Mo,W and X=S,Se. The calculations are based on 6-band tight-binding model of TMDCs, and then performing a semi-classical perturbation analysis of response functions. We numerically calculate the linear χ (1) µν (−ω; ω) and nonlinear surface susceptibility tensors χ (3) µνζη (−ωΣ; ωr, ωs, ωt) with ωΣ = ωr + ωs + ωt. Both non-degenerate and degenerate cases are studied for third-harmonic generation and nonlinear refractive index, respectively. Computational results obtained with no external fitting parameters are discussed regarding two recent reported experiments on MoS2, and thus we can confirm the extraordinarily strong optical nonlinearity of TMDCs. As a possible application, we demonstrate generation of a π 4 −rotated squeezed state by means of nonlinear response of TMDCs, in a silica micro-disk resonator covered with the 2D material. Our proposed method will enable accurate calculations of nonlinear optical response, such as four-wave mixing and high-harmonic generation in 2D materials and their heterostructures, thus enabling study of novel functionalities of 2D photonic integrated circuits.

Operator approach in nonlinear stochastic open quantum physics

“…3. The assumption for existence of a non-zero side-band inequivalence term in (268), (269), and ( 270) is supported by the fact that a non-zero value is actually admissible by the governing equations although it seems not possible to obtain an exact explicit solution.…”

Analysis of Side-band Inequivalence

“…Again, a full linear theory of Raman scattering [25] disallows SI. However, with the recent advent of low-dimensional materials, optical nonlinear interactions leading to Raman scattering [26,[31][32][33]38] and Kerr effect [34] are available at much stronger rates. Table 2 provides a summary of measurable SI based on the reported Raman scattering of different materials.…”

Role of Anisotropy in Nonlinear Harmonic Generation Across TMD Monolayers

“…Strong optical nonlinearities have been established through a myriad of methods. Second and third-order susceptibility have been both theoretically and experimentally studied in a wide range of TMD flakes [12,13], showing different responses. Z scans and pump-probe experiments have established a remarkably strong layerdependent nonlinear response in MoS 2 samples and also estimated relaxation rates [14].…”