CN-117214991-B - Mode division multiplexer based on five-core photonic crystal fiber

Abstract

The invention discloses a five-core photonic crystal fiber-based mode division multiplexer which comprises a substrate and an air hole layer area, wherein the air hole layer area is arranged on the substrate, the air hole layer area is formed by arranging a plurality of air holes, the air hole layer is divided into a fiber core area and a cladding area, the cladding area wraps the fiber core area, the fiber core comprises a main core area, a first side core area, a second side core area, a third side core area and a fourth side core area, the main core area is positioned at the center of the substrate, the first side core area, the second side core area, the third side core area and the fourth side core area encircle the main core area, and the cladding layer encircles the main core area. The invention modulates the incident light of the side core area into the coupling light in the main core area, improves the working bandwidth of the mode division multiplexer, reduces the insertion loss, and simultaneously effectively shortens the device length, so that the mode division multiplexer is suitable for miniaturized integrated optical fiber communication systems and mode division multiplexing systems.

Inventors

• HUI ZHANQIANG
• LV JIANXIN
• DU HUIMIN
• LI TIANTIAN
• HAN DONGDONG

Assignees

• 西安邮电大学
• 烽火通信科技股份有限公司

Dates

Publication Date

20260505

Application Date

20230818

Claims (4)

1. 1. The mode division multiplexer based on the five-core photonic crystal fiber is characterized by comprising a substrate and an air hole layer area, wherein the air hole layer area is arranged on the substrate; The air hole layer region is formed by arranging a plurality of air holes, the air hole layer is divided into a fiber core region and a cladding region, and the cladding region wraps the fiber core region; the fiber core comprises a main core area, a first side core area, a second side core area, a third side core area and a fourth side core area; the main core region is positioned at the center of the substrate, the first side core region, the second side core region, the third side core region and the fourth side core region surround the main core region, and the cladding surrounds the main core region; the main core area is a circular area formed by 1 seventh air hole (7), 1 eighth air hole (8), 1 ninth air hole (9), 1 tenth air hole (10) and a plurality of first air holes (1) in the cladding; the first side core area is a regular hexagon area formed by a plurality of second air holes (2) and 1 seventh air hole (7) in the cladding; the second side core area is a regular hexagon area formed by a plurality of third air holes (3) and 1 eighth air hole (8) in the cladding; the third side core area is a regular hexagon area formed by a plurality of fourth air holes (4) and 1 ninth air hole (9) in the cladding; The fourth side core area is a regular hexagon area formed by a plurality of fifth air holes (5) and 1 tenth air hole (10) in the cladding; The cladding region consists of a plurality of sixth air holes, the sixth air holes (6) encircle the fiber core region, and the center-to-center distance lambda 1 =4.975-5.025 mu m of every two adjacent sixth air holes (6); The first air hole (1), the second air hole (2), the third air hole (3), the fourth air hole (4), the fifth air hole (5), the sixth air hole (6), the seventh air hole (7), the eighth air hole (8), the ninth air hole (9) and the tenth air hole (10) are circular; The diameter of the fifth air hole (5) is r 5 =1.95-1.97 mu m; The diameter of the fourth air hole (4) is r 4 =1.67-1.69 mu m; The diameter of the sixth air hole (6) is r 6 =1.243-1.257 μm; The diameter of the third air hole (3) is r 3 =0.945-0.955 mu m; The diameter of the second air hole (2) is r 2 =0.646-0.654 mu m; The diameter of the tenth air hole (10) is r 10 =0.527-0.533 μm; The diameter of the first air hole (1) is r 1 =0.4975-0.5025 mu m; The diameter of the eighth air hole (8) is r 8 =0.477-0.483 μm; The diameter of the ninth air hole (9) is r 9 =0.447-0.453 μm; The diameter of the seventh air hole (7) is r 7 =0.368-0.372 μm.
2. 2. The five-core photonic crystal fiber-based mode splitter according to claim 1, wherein a center distance Λ 1 = 4.975-5.025 μm between adjacent two air holes in the main core region, the second side core region, the third side core region, and the fourth side core region, and a center distance Λ 2 = 5.97-6.03 μm between adjacent two air holes in the first side core region.
3. 3. The five-core photonic crystal fiber-based mode multiplexer according to claim 1, wherein 6 layers of air holes are arranged in the air hole layer region, and the first layer of air holes, the second layer of air holes, the third layer of air holes, the fourth layer of air holes, the fifth layer of air holes and the sixth layer of air holes are respectively formed from inside to outside; The first layer of air holes are formed into a circle by the sequence of 1 seventh air hole (7), 1 first air hole (1), 1 eighth air hole (8), 3 first air holes (1), 1 ninth air hole (9), 1 first air hole (1), 1 tenth air hole (10) and 3 first air holes (1); The second layer of air holes form a regular hexagon by the sequence of 2 second air holes (2), 2 third air holes (3), 3 sixth air holes (6), 2 fourth air holes (4), 2 fifth air holes (5) and 3 sixth air holes (6); The third layer of air holes comprise 3 second air holes (2), 1 sixth air hole (6), 3 third air holes (3), 5 sixth air holes (6), 3 fourth air holes (4), 1 sixth air hole (6), 3 fifth air holes (5) and 5 sixth air holes (6) which sequentially form a regular hexagon; the fourth layer of air holes are formed into regular hexagons by 26 sixth air holes (6); the fifth layer air holes are formed into regular hexagons by 34 sixth air holes (6); the sixth layer of air holes are formed into regular hexagons by 42 sixth air holes (6).
4. 4. The five-core photonic crystal fiber-based mode splitter of claim 1, wherein the substrate material is silica.

Description

Mode division multiplexer based on five-core photonic crystal fiber Technical Field The invention relates to the technical field of optical fiber communication, in particular to a mode division multiplexer based on a five-core photonic crystal fiber. Background In recent years, technologies such as cloud computing, big data, internet of things, unmanned operation, remote medical treatment and the like are rapidly rising, data transmission of the technologies is carried out through the internet, various optical multiplexing technologies (such as wavelength division multiplexing, time division multiplexing, polarization multiplexing and the like) and high-order modulation and coding are sequentially proposed by researchers in order to improve the capacity and transmission speed of a photon network, the total transmission capacity and the spectral efficiency of a single optical fiber are greatly improved, but with the progress of technology, the data flow transmission of the internet is exponentially increased year by year, the capacity transmission speed of a traditional single-mode optical fiber cannot meet the requirement of the internet transmission, and the capacity of the traditional single-mode optical fiber is very difficult to further improve. Therefore, in order to increase the capacity and transmission speed of the current photonic network, it is necessary to prompt researchers to explore new ways of multiplexing. The first time the concept of mode division multiplexing was proposed by s.berdague and p.facq, which use spatial filtering techniques to transmit light in two different modes in a conventional graded index multimode fiber, and each mode has the same bandwidth as when it is transmitted alone in a single mode fiber, which also reduces the nonlinear effects produced by transmitting information in a multimode fiber. The mode division multiplexing (Mode Division Multiplexing, abbreviated as MDM) technology refers to a technology that has multiple orthogonal modes with different paths and mode field distributions and carrying different information, and co-propagates in the same multimode optical waveguide. the core of the mode division multiplexing technology is a mode division multiplexer, and the performance of the mode division multiplexing system is determined by the mode multiplexing quantity, bandwidth, insertion loss and the like. According to different geometric structures, the existing mode division multiplexers are mainly classified into a free space optical path type, a multimode interferometer type (Multiode mode interference, abbreviated as MMI), an asymmetric directional coupler type (ASYMMETRY DIRECTIONAL COUPLER, abbreviated as ADC), an asymmetric Y-junction type, a 'photon lantern' type and a photon crystal optical fiber (Photonic crystal fiber, abbreviated as PCF) type. The PCF is also called a micro-structure optical fiber, the cladding or the fiber core of the PCF comprises wavelength magnitude air holes which are arranged in different ways, the air holes penetrate through the whole length of the optical fiber, light waves can be limited to propagate in a low-refractive-index optical fiber core region, and the light guiding characteristics which are not possessed by many traditional optical fibers, such as large mode field area, high nonlinearity, endless single mode, high birefringence characteristics, ultra-flat dispersion and the like, can be realized by adjusting the structure, the size and the arrangement mode of the air holes, so that the PCF has great design flexibility. Thus, the mode division multiplexer based on PCF design effectively shortens the size of the device, the mode multiplexer has wide working bandwidth and low insertion loss while greatly increasing the mode multiplexing number, so that .Chen M Y,Zhou J.Mode converter based on mode coupling in an asymmetric dual-core photonic crystal fibre[J].Journal of Optics A-pure and Applied Optics,2008,10(1334):1-5 provides a mode multiplexer based on mode coupling in an asymmetric double-core photonic crystal fiber in use and test, the mode multiplexer couples LP 01 and LP 02 modes in an optical fiber with the length of 12.7mm by introducing two adjacent defects into the photonic crystal fiber to form a large core and a small core, 1dB insertion loss ;D.J.Richardson,J.M.Fini,L.E.Nelson.Space-division multiplexing in optical fibres[J].Nature Photonics,2013,7(5) is obtained at the central wavelength of 1.55 mu m, MDM is provided to keep the transmission capacity of the optical fiber to develop along the Mooney law, and a three-mode spatial mode multiplexer is designed, the size of the mode multiplexer is large, the mode multiplexer is difficult to butt joint with a subsequent long-distance optical fiber mode multiplexing waveguide, the mode division multiplexer is difficult to obtain in miniaturized and integrated mode division multiplexing systems, a mode division multiplexer based on a three-core all-sol