Optical Harmonic Generation in 2D Materials

Abstract

2D materials are emerging as ideal candidates for fundamental investigations and new technologies due to their unique optoelectronic properties. Giant nonlinear susceptibility and perfect phase matching in 2D materials lead to extraordinary nonlinear light matter interactions, thus enabling several potential applications and fundamental scientific discoveries in nonlinear optics. For instance, second harmonic generation in 2D materials play an important role in optical devices such as, lasers, tunable waveguides, electro‐optic modulators, and switches. This review will discuss optical harmonic generation (OHG) processes, various characterization modes, and tuning techniques in 2D materials. The future prospectives for OHG in 2D materials is discussed. The extremely promising attributes of combining nonlinear optics and 2D materials is becoming a highly important multidisciplinary field.

Nano-engineering and nano-manufacturing in 2D materials: marvels of nanotechnology

“…Graphene and transition metal dichalcogenides (TMDCs) have been investigated extensively in the past decade, [1][2][3][4][5][6] shedding light on several applications and fundamental physics. [7][8][9][10][11] Recently, nano-engineering and nano manufacturing in the form of moire ´heterostructures, 12 wrinkle and fold formation 13 and substrate modulation 14 have led to numerous emergent and intriguing properties including superconductivity, 15 correlated insulator states, 16 topological conducting channels, 17,18 ferromagnetism, 19 enhanced electron mobility, 20 harmonic generation and remarkable optoelectronic properties. 18,21,22 This advancement in nanotechnology at the atomic level has been leveraged in a wide range of applications such as mechanically reconfigurable quantum materials, wearable electronics and nanosystems.…”

Liquid-Phase Exfoliation of Bismuth Telluride Iodide (BiTeI): Structural and Optical Properties of Single-/Few-Layer Flakes

“…94 Even more, since the nanometric thickness of exfoliated materials is much smaller than the second-harmonic (SH) coherence length, 2D materials bypass phase-matching constraints encountered in 3D nonlinear crystals. 95,96 Thus, we measure SHG from few-layer BiTeI flakes, which exhibit a large nonlinear optical response 10-fold more intense than that of bulk BiTeI crystals and of the same order of magnitude as that of group VI monolayer transition metal dichalcogenides (TMDs) (|χ (2) | ∼0.1−1 nm V −1 ). 95,97 These results prove the potential of LPE-produced BiTeI as a solution-processable low-dimensional Rashba-type material.…”

Second Harmonic Helicity and Faraday Rotation in Gated Single-Layer 1T$'$-WTe$_2$

“…Two dimensional (2D) materials such as transition metal dichalcogenides (TMDs), with chemical formula MX 2 where M stands for the transition metal atom (W, Mo) and X is the chalcogen atom (Te, Se or S), appear in different crystalline structures such as hexagonal 2H, tetragonal 1T, and distorted 1T and 1T d structures [1][2][3]. Noncentrosymmetric TMDs exhibit unique physical properties such as circular dichroism, piezoelectricity, nonlinear Hall effect and second harmonic generation due to their distinct phases [4][5][6][7][8][9][10][11][12]. The distorted 2D WTe 2 is attracting a surge of interest due to diverse ground state phases such as quantum spin Hall, superconductivity, polar metal and ferroelectricity [13][14][15][16][17].…”