CN-224216904-U - Eight-mode multiplexer/demultiplexer based on refractive index step type elliptical core main channel

Abstract

An eight-mode multiplexer/demultiplexer based on a refractive index step-type elliptical core main channel comprises 1 eight-mode elliptical fiber core (EC) and 7 equal-length single-mode fiber cores, wherein the length of the elliptical fiber core transmission main channel is 17.6mm, the ellipticity rho of the elliptical fiber core is 1.58, the length of a long half axis is 7.02 mu m, the length of a short half axis is 4.44 mu m, the lengths of SMF-HG10, SMF-HG01, SMF-HG20, SMF-HG11, SMF-HG30, SMF-HG02 and SMF-HG21 serving as side cores are all 3.8mm, and the multiplexer/demultiplexer is a transmission coupling channel.

Inventors

• JIN HONGWEI
• ZENG KUN
• ZHENG HONGJUN
• LI XIN
• BAI CHENGLIN
• HU WEISHENG

Assignees

• 聊城大学

Dates

Publication Date

20260508

Application Date

20250613

Claims (1)

1. 1. An eight-mode multiplexer/demultiplexer based on a refractive index step-type elliptical core main channel is characterized in that the multiplexer/demultiplexer is divided into two sections by 1 eight-mode elliptical fiber core (EC) and 7 equal-length single-mode fiber cores to form a transmission channel, the elliptical fiber core in the coordinate center penetrates through the two sections as the transmission main channel, wherein the second section starts at 10mm after the coupling length of the first section, the first section is Shan Moqian cores SMF-HG10 on the X coordinate axis, SMF-HG01 on the Y coordinate axis, SMF-HG20 on the-X coordinate axis, SMF-HG02 on the-Y coordinate axis, the second section is SMF-HG11 on the first quadrant 45 DEG direction, The SMF-HG30 is on the-X coordinate axis and the SMF-HG21 is on the fourth quadrant 30 DEG, the elliptic fiber core transmission channel is a main channel of the mode division multiplexing/demultiplexing, is placed on the z axis, the axes of the elliptic fiber core transmission channel are overlapped with the z axis, the supporting modes HG00, HG10, HG01, HG20, HG11, HG30, HG02 and HG21 are supported, seven equal-length single-mode fiber cores SMF-HG10, SMF-HG01, SMF-HG20, SMF-HG11, SMF-HG30, SMF-HG02 and SMF-HG21 serving as side cores are single-mode circular core transmission coupling channels, and are placed on the positive half axis of the X axis and the negative half axis of the first quadrant 45 DEG and the negative half axis of the X axis and the negative half axis of the Y axis and the fourth quadrant 30 DEG, SMF-HG10, SMF-HG01, SMF-HG20 and SMF-HG02 axes are parallel to the axis of the elliptic fiber core from respective starting points, SMF-HG11, SMF-HG30 and SMF-HG21 are parallel to the axis of the elliptic fiber core at 10mm after the first section of coupling length, according to the theory of coupling mode, mode HG00 is transmitted from left end to right end along the elliptic fiber core transmission main channel to realize multiplexing output function, other light fields are respectively incident from left end of SMF corresponding to HG10, HG01, HG20, HG11, HG30, HG02 and HG21 and are respectively coupled to mode HG10, mode HG10 in the elliptic fiber core transmission main channel, HG01, HG20, HG11, HG30, HG02 and HG21 are output in modes of HG10, HG01, HG20, HG11, HG30, HG02 and HG21 at the right end of the elliptical core transmission main channel, 8 modes of HG00, HG10, HG01, HG20, HG11, HG30, HG02 and HG21 are multiplexed in the modes of the elliptical core transmission main channel, if the modes of HG00, HG10, HG01, HG20, HG11, HG30, HG02 and HG21 are incident from the left end of the elliptical core transmission main channel and are decoupled in transmission coupling along the z direction, according to the theory of a coupling mode, the modes of HG00 are demultiplexed from the left end to the right end along the elliptical core transmission main channel, and the modes of HG10, HG01, HG20, HG11, HG30, HG02 and HG21 are incident from the left end of the elliptic core transmission main channel, and respectively transmit and couple to the right end outputs of SMFs corresponding to modes HG10, HG01, HG20, HG11, HG30, HG02 and HG21, so that 8 modes HG00, HG10, HG01, HG20, HG11, HG30, HG02 and HG21 are demultiplexed from the elliptic core transmission main channel modes, the central coordinates of the eight-mode elliptic core transmission main channel are (0, 0) according to the change relation of the mode coupling length and the channel spacing, the length of the elliptic core transmission main channel is 17.6mm, the ellipticity p of the elliptic core is 1.58, the length of a long half shaft is 7.02 mu m, the length of a short half shaft is 4.44 mu m, the SMF-HG10, The center-to-center distances of the transmission main channels of SMF-HG01, SMFHG, SMF-HG11, SMF-HG30, SMF-HG02 and SMF-HG21 are respectively 12.12, 10.74, 13.22, 12.62, 10.84 And The lengths of the components are 3.8mm, and the radii of the components are 3 mu m for SMF-HG10, SMF-HG01, SMF-HG20, SMF-HG11, SMF-HG30, SMF-HG02 and SMF-HG 21; the elliptical fiber core adopts step-index distribution which is higher than the refractive index of a peripheral cladding, the elliptical fiber core with high refractive index and the single-mode fiber core are mainly used for transmitting light, the single-mode fiber cores SMF-HG10, SMF-HG01, SMF-HG20, SMF-HG11, SMF-HG30, SMF-HG02 and SMF-HG21 respectively adopt step-index distribution which is 1.437988, 1.435368, 1.433626, 1.431141, 1.428153, 1.427105 and 1.426017, the elliptical fiber core transmission main channel adopts pure silica materials, the refractive index is n 1 = 1.4440, the cladding part adopts fluorine-doped silica materials, the refractive index is n 2 = 1.4240, the mode characteristics of the mode fields in the optical fiber are changed by reasonably setting the positions, the sizes and the refractive index distribution of the fiber cores, the multiplexer de-multiplexer breaks the modes of HG30 and HG02, the degeneracy difference between the modes is larger than 1×10 -3 , the mode-preserving function is realized, the loss is reduced by adopting the pure silica fiber cores, the side core is divided into two sections of HG00, the coupling, HG01, HG11 and the multiplexing operation with low-HG 02 and the multiplexing operation with the low-frequency-HG 02 is realized.

Description

Eight-mode multiplexer/demultiplexer based on refractive index step type elliptical core main channel Technical Field The invention relates to an eight-mode multiplexer/demultiplexer based on a refractive index step type main channel, which can be applied to the fields of optical fiber optics, optical fiber communication, optical fiber wireless access, optical information processing, new generation information technology and the like. Background In the field of modern optical communications, as data traffic increases exponentially, there is an increasing demand for increasing the capacity of a communications system. Conventional single mode fiber communication systems are increasingly challenged with the unprecedented challenge of few-mode fiber (FMF) technology, which is expected to greatly increase the transmission capacity of an optical fiber by transmitting multiple modes of optical signals in one fiber. The optical fiber communication industry breaks through the transmission capacity of the communication network around the physical dimension of space division multiplexing (including core multiplexing and mode division multiplexing and combination thereof); the mode division multiplexing and few-mode optical fibers in space division multiplexing and related devices and application researches become leading-edge research hotspots [Sun Hyok Chang,Hwan Seok Chung,Nicolas K.Fontaine,Roland Ryf,Kyung Jun Park,Kwangjoon Kim,Jyung Chan Lee,Jong Hyun Lee,Byoung Yoon Kim,and Young Kie Kim,″Mode division multiplexed optical transmission enabled by all-fiber mode multiplexer,″Opt.Express 22,14229-14236(2014);Yanlei Li,Xiao Wang,Hongjun Zheng,Xin Li,Chenglin Bai,Weisheng Hu,Yang Liu,Qiuhuan Dong,A novel six-core few-mode fiber with low loss and low crosstalk,Optical Fiber Technology,Volume57,2020,102211; Gao Yan, li Yanlei, xing Huadong, dawn, zheng Hongjun, bai Chenglin, hu Weisheng, xu Hengying, yin Yingxin, dong Qiuhuan, mode division multiplexing optical transmission technology research, university of Liaocheng (natural science edition), liaocheng (1): 30-56; liaocheng, li 2, liaocheng, the transmission of chirped pulses in optical fibers, beijing: scientific press, liaocheng-184, liaocheng, liaocheng, liaocheng, li 2, liaocheng, liaocheng, liaocheng, the small-mode multiplexing (demultiplexing) technology research of the university of Li 2, liaocheng (2): 50-67, liaocheng, liaocheng x (the communication authors), li 2, liaocheng, the new progress of the small-mode optical fiber research of the university of Li 2, liaocheng, liaocheng (2): 69-79] in the mode multiplexing system, the effective reduction of fiber attenuation and fusion loss of the pure silica cores, the small-mode optical fiber supporting the number of transmission modes, and the small difference of transmission paths between different modes, are currently applied to single-mode optical fibers Liaocheng in most cases compared with multi-core optical fibers. In addition, the transmission capacity can be significantly improved by combining the mode division multiplexing technology in the space division multiplexing. However, in a mode division multiplexing system based on few-mode optical fibers, as modes increase, crosstalk exists between adjacent modes, so as to affect communication quality ;[Jiajia Zhao,Ming Tang,Kyunghwan Oh,Zhenhua Feng,Can Zhao,Ruolin Liao,Songnian Fu,Perry Ping Shum,and Deming Liu,″Polarization-maintaining few mode fiber composed of a central circular-hole and an elliptical-ring core,″Photon.Res.5,261-266(2017);Jiwei Zhang,Guoru Wang,Han Zhang,et al.A weakly-coupled few-mode optical fiber with a graded concave high-index-ring[J].IEEE Photonics Journal,2021,13：7200710];, a mode division multiplexing transmission method .[A.R.May and M.N.Zervas,″Few-mode fibers with improved mode spacing,″2015European Conference on Optical Communication(ECOC),2015,pp.1-3,doi：10.1109/ECOC.2015.7341706;Tao Hu,Juhao Li,Dawei Ge,Zhongying Wu,Yu Tian,Lei Shen,Yaping Liu,Su Chen,Zhenghin Li,Yongqi He,and Zhangyuan Chen,″Weakly-coupled 4-mode step-index FMF and demonstration of IM/DD MDM transmissiOn,″Opt.Express 26,8356-8363(2018);Jiang,Shoulin and Ma,Lin and Zhang,Zhaopeng and Xu,Xiao and Wang,Shuai and Du,Jiangbing and Yang,Chen and Tong,Weijun and He,Zuyuan,″Design and Characterization of Ring-Assisted Few-Mode Fibers for Weakly Coupled Mode-Division Multiplexing Transmission,″in Journal of Lightwave Technology,vol.36,no.23,pp.5547-5555,1Dec.1,2018,doi：10.1109/JLT.2018.2874526;Dawei Ge,Yuyang Gao,Yu Yang,Lei Shen,Zhengbin Li,Zhangyuan Chen,Yongqi He,Juhao Li,″A 6-LP-mode ultralow-modal-crosstalk double-ring-core FMF for weakly-coupled MDM transmission,″Optics Communications,vo1.451,pp.97-103,Nov.2019]; for suppressing mode crosstalk is proposed for optical elements such as few-mode optical fiber transmission and a mode division multiplexer/demultiplexer, but these round-core few-mode optical fibers still have larger mode degeneracy, mode crosstal