Abstract
This paper proposes a novel refractive index profile design based on few-mode fibers (FMFs) which can support 4 linear polarization (LP) modes. We first present a FMF whose core is dually assisted by a nano-hole (NH) and a high-index-ring (HIR), and then substitute the dual assistance by an innovative graded concave HIR (GC-HIR) assisted structure. Using the finite element method (FEM), the parameters of the NH-HIR and GC-HIR optical fiber are adjusted to investigate their respective minimum effective refractive index difference (minΔn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">eff</sub> ), which is 2.012 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> for the former, and 2.532 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> for the latter. Both optical fibers have a significant improvement on the crosstalk suppression effect, and the GC-HIR optical fiber is even better. The proposed GC-HIR FMF with special refractive index profile has potential application prospects in mode division multiplexing (MDM) optical fiber communication system, and can provide theoretical foundation for the design and analysis of subsequent optical fibers and key components.
Highlights
With the development of optical fiber communication, multiplexing technology is widely used to improve communication capacity
This paper proposes a novel refractive index profile design based on few-mode fibers (FMFs) which can support 4 linear polarization (LP) modes
As a solution to the inter-mode crosstalk, multiple input multiple output digital signal processing (MIMO-DSP) is a commonly adopted method, but with the increase of the mode number, the complexity and power consumption of the transmission system would increase greatly [12]–[14]. Another solution is to increase the effective refractive index difference between adjacent modes through optical fiber design, which promotes the development of a variety of new optical fiber structures. neff in cores is mainly related to the core refractive index (RI) profile, and relevant research shows that neff ≥10−3 [15] can effectively reduce the inter-mode coupling
Summary
Jiwei Zhang Guorui Wang Han Zhang Fang Wang Xin Yan Xuenan Zhang Shuguang Li Tonglei Cheng.
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