Borda-Hernández José A, Serpa-Imbett Claudia M, Figueroa Hugo E Hernandez
Department of Communications, School of Electrical and Computer Engineering, University of Campinas, Campinas, SP 13083-852, Brazil.
ITEM Research Group, Department of Electronic Engineering, Universidad Pontificia Bolivariana Sede Monteria, Km 6 Via Cerete, Monteria, Córdoba 230002, Colombia.
Polymers (Basel). 2020 Nov 24;12(12):2776. doi: 10.3390/polym12122776.
This research introduces a numerical design of an air-core vortex polymer optical fiber in cyclic transparent optical polymer (CYTOP) that propagates 32 orbital angular momentum (OAM) modes, i.e., it may support up to 64 stable OAM-states considering left- and right-handed circular polarizations. This fiber seeks to be an alternative to increase the capacity of short-range optical communication systems multiplexed by modes, in agreement with the high demand of low-cost, insensitive-to-bending and easy-to-handle fibers similar to others optical fibers fabricated in polymers. This novel fiber possesses unique characteristics: a diameter of 50 µm that would allow a high mechanical compatibility with commercially available polymer optical fibers, a difference of effective index between neighbor OAM modes of around 10 over a bandwidth from 1 to 1.6 µm, propagation losses of approximately 15 × 10 dB/m for all OAM modes, and a very low dispersion for OAM higher order modes (± = 16) of up to +2.5 ps/km-nm compared with OAM lower order modes at a telecom wavelength of 1.3 µm, in which the CYTOP exhibits a minimal attenuation. The spectra of mutual coupling coefficients between modes are computed considering small bends of up to 3 cm of radius and slight ellipticity in the ring of up to 5%. Results show lower-charge weights for higher order OAM modes.
本研究介绍了一种在环状透明光学聚合物（CYTOP）中设计的空芯涡旋聚合物光纤的数值方案，该光纤可传播32种轨道角动量（OAM）模式，即考虑左旋和右旋圆偏振时，它可支持多达64种稳定的OAM态。这种光纤旨在成为一种替代方案，以增加通过模式复用的短程光通信系统的容量，这与对低成本、抗弯曲且易于处理的光纤的高需求相一致，类似于其他用聚合物制造的光纤。这种新型光纤具有独特的特性：直径为50 µm，这将使其与市售聚合物光纤具有高度的机械兼容性；在1至1.6 µm的带宽内，相邻OAM模式之间的有效折射率差约为10；所有OAM模式的传播损耗约为15×10 dB/m；在1.3 µm的电信波长下，与低阶OAM模式相比，高阶OAM模式（± = 16）的色散非常低，高达+2.5 ps/km-nm，其中CYTOP的衰减最小。考虑到半径达3 cm的小弯曲和环中高达5%的轻微椭圆率，计算了模式间的相互耦合系数谱。结果表明，高阶OAM模式的电荷权重较低。
