Giant Anisotropy and High Second-Order Nonlinearity of 3R-MoS₂ for Multifunctional Photonics

Area of Science:

• Nanophotonics
• Materials Science
• Nonlinear Optics

Background:

• Miniaturizing photonic circuits is challenging due to difficulties in combining nonlinear frequency conversion with subdiffractional light guiding.
• Existing molybdenum disulfide (MoS₂) materials often lack the necessary properties for multifunctional integration.

Purpose of the Study:

• To establish a multifunctional platform for integrated nanophotonics.
• To explore the potential of the 3R-polytype of MoS₂ (3R-MoS₂) for advanced photonic applications.

Main Methods:

• Fabrication and characterization of 3R-MoS₂.
• Measurement of linear and nonlinear optical properties, including the dielectric tensor.
• Demonstration of extreme skin-depth (e-skid) waveguides and tunable Fabry-Pérot resonators.

Main Results:

• 3R-MoS₂ exhibits broken inversion symmetry, enabling second-order nonlinearity.
• 3R-MoS₂ possesses giant optical anisotropy, exceeding that of its 2H counterpart.
• Subdiffractional light confinement was achieved with mode sizes 20% below the diffraction limit.
• Enhanced second-harmonic generation with an effective nonlinear response of 1.2 nm/V was demonstrated.

Conclusions:

• 3R-MoS₂ serves as a multifunctional platform overcoming limitations in photonic circuit miniaturization.
• The unique optical properties of 3R-MoS₂ facilitate high-density nanophotonic integration.
• This material advances the development of integrated active and passive photonic devices.