Azimuthally and radially polarized orbital angular momentum modes in valley topological photonic crystal fiber

Zhishen Zhang,Jiuyang Lu,Minbo Wu,Jiulin Gan,Feng Li,Xiaobo Heng,Tao Liu,Zhongmin Yang

doi:10.1515/nanoph-2021-0395

Abstract

Abstract Artificially tailoring the polarization and phase of light offers new applications in optical communication, optical tweezers, and laser processing. Valley topological physics provides a novel paradigm for controlling electromagnetic waves and encoding information. The proposed fiber has the inner and outer claddings possessing opposite valley topological phases but the same refractive indices, which breaks through the polarization constraints of the traditional fiber. Robust valley edge states exist at the domain walls between the inner and outer claddings because of bulk edge correspondence. The valley topological fiber modes exhibit the unprecedented radial and azimuthal polarization with high-order azimuthal index. Those topological modes are robust against the disorder of the fiber structure. These results enable guide and manipulate the optical polarization and angular momentum in fiber with high fidelity. The proposed fiber has the potential to become a powerful optical spanner for the application of bio-photonics.

Highlights

Polarization and phase are two important properties of light and spatially arranging the polarization and phase [1,2,3] leads to intriguing applications in optical communication [4, 5], optical tweezers [6, 7], and laser processing [8, 9]
The rotation angle of the threehole α controls the topological properties of the photonic crystal
Compared with the in-plane propagation in the 2D photonic topological insulators, the light can propagate in directions that lie outside the transverse

Summary

Introduction

Polarization and phase are two important properties of light and spatially arranging the polarization and phase [1,2,3] leads to intriguing applications in optical communication [4, 5], optical tweezers [6, 7], and laser processing [8, 9]. The azimuthally/radially polarized OAM fiber will combine the advantages of the azimuthally/radially polarized lights, the OAM lights, and the fiber lights, and leads to the potential application as the low-energy great-strength optical spanner into biological tissues. The polarization and phase of fiber modes rely heavily on the azimuthal index. According to the wave equation [14], the refractive indices contrast between fiber core and cladding divides the fiber modes into three categories, the linear or circular polarized modes, the azimuthally polarized modes, and the radially polarized modes. The latter two cases can only be achieved with zero azimuthal index [14].

Methods

Results

Conclusion