In-fibre second-harmonic generation with embedded two-dimensional materials

TLDR

Silica optical fibres are widely used for nonlinear optics but lack intrinsic second‑order nonlinearity because silica is amorphous. The study demonstrates second‑harmonic generation in optical fibres by integrating a monolayer MoS₂ directly on the fibre core. The method employs a monolayer MoS₂ grown on the fibre core, scalable to other transition metal dichalcogenides and waveguide platforms. The MoS₂‑functionalised fibre achieves a χ(2) of 44 pm V⁻¹ and a conversion efficiency of 2 × 10⁻⁴ m⁻² W⁻¹, establishing a new platform for efficient in‑fibre second‑harmonic generation and potential χ(2)‑based photonic applications.

Abstract

Abstract Silica-based optical fibres are a workhorse of nonlinear optics, providing ready access to a range of nonlinear phenomena including solitons and self-phase modulation. However, they have one fundamental limitation: due to the amorphous nature of silica, they do not exhibit second-order nonlinearity, except for negligible contributions from surfaces. Here we demonstrate second-harmonic generation in functionalized optical fibres by using a monolayer of highly nonlinear MoS 2 directly grown on the fibre’s core. The MoS 2 -functionalized fibre exhibits a second-order susceptibility ( χ (2) ) value of 44 pm V –1 and a second-harmonic generation conversion efficiency of 0.2 × 10 –3 m −2 W −1 . This approach is scalable and can be generalized to other transition metal dichalcogenides and a wide range of waveguide systems. Our results demonstrate a new approach towards efficient in-fibre second-harmonic generation sources and may establish a platform for χ (2) -based nonlinear fibre optics, optoelectronics, photonics platforms, integrated optical architectures and active fibre networks.