A Novel Liquid Crystal-Filled, Dual-Core Photonic Crystal Fiber Polarization Beam Splitter Covering the E + S + C + L + U Communication Band

Yuwei Qu,Ying Han,Chongxiu Yu,Jinhui Yuan,Binbin Yan,Xinzhu Sang,Kuiru Wang,Xian Zhou

doi:10.3390/photonics8110461

Abstract

This paper proposes a novel liquid crystal-filled, dual core photonic crystal fiber polarization beam splitter (LC-DC-PCF PBS) based on the coupled mode theory of DC-PCF. The mode birefringence of odd and even modes, coupling lengths (CLs) of the X-polarization (X-pol) and Y-polarization (Y-pol), and the corresponding coupling length ratio (CLR) of the proposed LC-DC-PCF PBS filled without LC E7 and with LC E7 are compared. The change rules of the CLs of the X-pol and Y-pol and CLR of the proposed LC-DC-PCF with wavelengths for different cladding microstructure parameters were investigated. The relationships between the X-pol and Y-pol normalized output powers in core A of the proposed LC-DC-PCF PBS and the propagation length at the wavelength of 1.604 μm are discussed. Finally, by studying the change of extinction ratio (ER) with wavelength, the LC-DC-PCF PBS ER of 60.3 and 72.2 dB at wavelengths 1.386 and 1.619 μm are achieved, respectively. The final splitting length (LS) is 94 μm, and the splitting bandwidth is 349 nm (1.352~1.701 μm), covering the whole of the E + S + C + L + U communication bands. The proposed LC-DC-PCF PBS has good beam-splitting performance, such as ultra-short LS and ultra-wide splitting bandwidth, with potential applications in laser, sensing, and communication systems.

Highlights

We propose a novel liquid crystal (LC)-filled DC-photonic crystal fiber (PCF) (LC-dual-core photonic crystal fiber (DC-PCF)) polarization beam splitter (PBS) based on the DC-PCF-coupled mode theory
The minimum difference is much larger than when the LC-DC-PCF is filled without LC E7
LC E7, the maximum CLX and CLY are smaller than the minimum CLX and CLY when the LC-DC-PCF is filled without LC E7, and the coupling length ratio (CLR) value in the range of 1.3~1.8 μm is closer to the optimal CLR = 2

Summary

Introduction

In the late 1990s, J.C. Knight et al proposed and successfully fabricated the first photonic crystal fiber (PCF), whose cladding was composed of micron-sized air holes arranged according to certain rules [1,2,3]. In the following 20 years, due to the flexible cladding microstructure of PCF and the maturity of fiber post-processing technology, the PCF has experienced incredible development in various fields of optics and photonics [4,5,6,7,8,9,10]. After all six optical fiber communication windows O (1260–1360 nm), E (1360–1460 nm), S (1460–1530 nm), C (1530–1565 nm), L (1565–1625 nm), and U (1625–1675 nm) are proposed, PCF has more significant advantages in the field of multi window optical fiber communication

Methods

Results

Discussion

Conclusion