All-fiber polarization-manageable directional couplers

TL;DR

This paper introduces a novel all-fiber directional coupler design that enables flexible polarization management, including splitting, rotation, and exchange of fiber-guided modes, enhancing control in optical communication and sensing systems.

Contribution

The paper presents a new structural design of three-core fiber couplers with an embedded vector mode segregated core for arbitrary polarization management, a capability not previously achieved in all-fiber devices.

Findings

Demonstrates polarization split, rotation, and exchange in fiber couplers

Numerical simulations show favorable polarization management performance

Introduces a new degree of freedom for modal polarization control

Abstract

Flexible management of light polarization is necessary to develop the technologies of optical fiber communications. However, it is still a great challenge to manipulate optical polarization in all-fiberbased devices. Here we present a novel structural design of three-core fiber couplers to create arbitrary polarization management by embedding a vector mode segregated core within the conventional fiber couplers. We take advantages of these coupling structures to achieve polarization split, rotation, and exchange, as three essential polarization managements for fiber-guided modes. We study these couplers based on coupled-mode theory and numerically simulations. The obtained results show that they manifest favorable operation performance on management of the fiber modal polarization states. Compared to previous couplers used for management of power, wavelengths and modal forms, this kind of fiber couplers introduces a new manageable degree of freedom for modal polarization. It is expected that the presented all-fiber polarization-manageable directional couplers might find potential applications in fiber optical communications and sensing systems.