All Photonic Isolator using Atomically Thin (2D) Bismuth Telluride (Bi2Te3)

TL;DR

This paper demonstrates that atomically thin Bi2Te3 exhibits strong broadband Kerr nonlinearity, enabling the development of a nonlinear photonic isolator that breaks time-reversal symmetry and allows unidirectional light propagation.

Contribution

The study introduces 2D Bi2Te3 as a novel material for nonlinear photonics and demonstrates a photonic isolator based on its Kerr nonlinearity.

Findings

2D Bi2Te3 has a higher nonlinear refractive index than graphene.

Surface engineering enhances the response speed of the photonic system.

A functional nonlinear photonic isolator was successfully demonstrated.

Abstract

This study demonstrates that two-dimensional (2D) Bi2Te3 exhibits strong light-matter interaction, enabling a broadband Kerr nonlinear optical response. This characteristic is advantageous for nonreciprocal light propagation in passive photonic isolators. Using Spatial Self-Phase Modulation (SSPM) spectroscopy, self-induced diffraction patterns in the far field were observed at excitation wavelengths of 650 nm, 532 nm, and 405 nm to calculate the nonlinear refractive index (n2) and the third-order nonlinear optical susceptibility (chi^(3)) of the synthesized 2D Bi2Te3. The results show that 2D Bi2Te3 possesses a significantly higher nonlinear refractive index than graphene. The laser-induced hole coherence effect is responsible for the large magnitude of the third-order nonlinear susceptibility. Surface engineering techniques were also employed to enhance the response speed of the photonic system. Complementary ab initio simulations were performed to gain further insight into the observed nonlinear behavior. Leveraging the strong Kerr nonlinearity of 2D Bi2Te3, a nonlinear photonic isolator that breaks time-reversal symmetry and enables unidirectional light propagation was demonstrated. This work establishes Bi2Te3 as a novel 2D material for nonlinear photonics, expanding its potential applications in detectors, modulators, and optical switches.