Design and Analysis of Ultra-Wideband Highly-Birefringent Bragg Layered Photonic Bandgap Fiber With Concave-Index Cladding

Hongyu Tan,Botao Deng,Deming Liu,Jianghe Xu,Zhenggang Lian,Chaotan Sima,Qianqing Yu,Guoqun Chen,Xiaohang Zhang

doi:10.1109/jphot.2021.3075446

Hongyu Tan, Botao Deng + Show 7 more

Open Access

https://doi.org/10.1109/jphot.2021.3075446

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Abstract

A ultra-wideband highly-birefringent Bragg layered photonic bandgap fiber (BL-PBGF) with concave-index cladding is proposed and demonstrated, by incorporating PBG effect with Bragg multilayers for the first time to the best of our knowledge. The proposed BL-PBGF contains honeycomb capillary cladding and elliptical core with horizontal asymmetry for birefringence. By innovatively introducing three modified silica capillary layers with different refractive indices, the cladding with concave-convex refractive index distribution is combined, providing superior characteristics for optical polarization implementation, such as confinement loss, bending loss and birefringence. Results show that the confinement loss stays around 2 dB/km level within ultrawide 180 nm wavelength range, basically 3 times wider than conventional PBGF. The birefringence maintains at the order of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> across the entire bandwidth and the maximum value reaches 2.5 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> . The bending loss at 1550 nm is significantly reduced to below one third of the conventional uniform index PBGF when the bending radius is less than 3.5 mm, and maintains below 1 dB/km level when the bending radius is beyond 10 mm. The proposed universal BL-PBGF has great potential in minimized freestanding fiber coil and small footprint fiber optical gyroscope applications.

Highlights

The highly-birefringent optical fiber, named as polarization-maintaining fiber (PMF), has been widely used in optical sensing and optical communication since 1979[1]
With the rapid development of communication systems and advanced sensing applications, novel PMFs are in need to meet demands of high birefringence as well as thermal and radiation stability in practical utilizations [2,3]
Structural symmetry of the photonic crystal fiber (PCF) could be interrupted by changing geometry and layout of core and cladding air holes, thereby obtaining high birefringence [6,7,8,9,10,11]

Summary

Introduction

The highly-birefringent optical fiber, named as polarization-maintaining fiber (PMF), has been widely used in optical sensing and optical communication since 1979[1]. The bending loss of the proposed BL-PBGF becomes less than one third of the conventional PBGF when bending radius is below 3.5 mm and maintains below 1 dB/km when the bending radius is beyond 10 mm The birefringence of this fiber can be maintained at the order of 10-3 across the wide bandwidth and shows excellent polarization maintenance with small bending radius. These benefits provide great potential in the miniature freestanding fiber coil and small footprint FOG applications

Principle and Structure

Optical characteristics analysis

Confinement loss

Sensitivity and tolerance analysis

Findings

Conclusion