CN207908738U - A kind of three pattern mode division multiplexing device of low crosstalk graded--index planar waveguides - Google Patents

Abstract

The utility model proposes a kind of three pattern mode division multiplexing devices of low crosstalk graded--index planar waveguides, including 3 identical transmission channel compositions, one of them is main transmission channel；20 μm of transmission channel radius, transmission channel fibre core and cladding index poor 0.0015, cladding index 1.442524；The refractive index of channel core center to covering changes in gradation type；Pattern LP01 directly inputs main transmission channel；Pattern LP11a and LP11b channel is individually positioned on the main transmission channel cross section direction x and y, and channel length is 28 mm, and the spacing with main channel is 5 μm.

Description

A kind of three pattern mode division multiplexing device of low crosstalk graded--index planar waveguides

Technical field

Present patent application is related to a kind of mode division multiplexing structure, and in particular to a kind of three pattern of low crosstalk graded--index planar waveguides Mode division multiplexing device can be applied to the generation information technologies such as fiber optic communication, optical Information Processing field.

Background technology

In recent years, the fiber optic communication field based on mode division multiplexing is one of forward position research hotspot；As its key technology it One mode division multiplexing device gets the attention [1Guifang Li, Neng Bai, and Ningbo Zhao and Cen Xia,Space-division multiplexing:the next frontier in optical communication.Advances in Optics&Photonics,2014,6(4):5041–5046；2He Wen, Hongjun Zheng,et al.Few-Mode Fibre-Optic Microwave Photonic Links,Light: Science&Applications,2017.8,6,e17021,1-8]；As the key technique of mode division multiplexing system, mould point Multiplexer is the device for being transmitted various modes signal multiplexing to the same channel, is had to the realization of mode division multiplexing system Significance.Document [3RolRyf, Bolle C A, Hoyningenhuene J V.Optical Coupling Components for Spatial Multiplexing in Multi-Mode[C].European Conference and Exhibition on Optical Communication (ECOC).2011:1-3] propose a kind of mould based on phase-plate Division multiplexer realizes three kinds of mode changeover signals and is multiplexed into the same channel, but this mode division multiplexing device needs are high-precision The Space Coupling of exactness is calibrated, and is difficult to integrate, and the insertion loss of free space coupling is big, of high cost.Document [4Fontaine N K,Ryf R, Leonsaval S G,et al.Evaluation of Photonic Lanterns for Lossless Mode-Multiplexing[C].38th European Conference and Exhibition on Optical Communications(ECOC),2012:1-3；5Ryf R,Fontaine N K,Montoliu M,et al. Photonic- lantern-based mode multiplexers for few-mode-fiber transmission[C]. Optical Fiber Communications Conference and Exhibition(OFC),2014:1-3；6 Leonsaval S G, Fontaine N K,Salazargil J R,et al.Mode-selective photonic lanterns for space- division multiplexing[J].Optics Express,2014,22(1):1036-44] propose a kind of drawing cone-shaped " photon lantern " mode division multiplexing device, realize 12 road mode changeover signals and be multiplexed into the same channel." photon lantern " Although complex degree of structure is lower than space coupler, its manufacturing process is accurate, complicated, when accurately controlling fiber fuse Position draws cone thickness and length to have great difficulty, volume production difficulty larger；By draw taper at output port and transmission it is logical Road Incomplete matching can lead to high loss.[it is lucky that 7 stones are good for mode division multiplexing Research on Communication Technology [D] of based on less fundamental mode optical fibre to document Woods university, 2013] mode division multiplexing/demultiplexer based on asymmetric slab guide is devised, it realizes the multiplexing of pattern, demultiplex With also achieving the conversion of pattern；But that there are service bands is narrow for the plane multiplexer, it is difficult to it is integrated, it is tired with fused fiber splice Difficult problem.Document [8Huang B, Xia C, Matz G, et al.Structured directional coupler pair for multiplexing of degenerate modes[C].Optical Fiber Communication Conference and Exposition and the National Fiber Optic Engineers Conference (OFC/NFOEC),2013:1-3；9Xie Y,Fu S,Liu H,et al.Design and numerical optimization of a mode multiplexer based on few-mode fiber couplers[J] .Journal of Optics,2013,15(12):3901-3901；10Tsekrekos C P,Syvridis D.Symmetric Few-Mode Fiber Couplers as the Key Component for Broadband Mode Multiplexing [J].Journal of Lightwave Technology,2014,32(14):2461-2467；11Simon Gross, Nicolas Riesen,John D.Love and Michael J.Withford,Mode-Division Multiplexing using Femtosecond Laser Written 3-Dimensional Tapered Couplers,OECC/ACOFT 2014.7,156-158] in devise the multiplexer of the direct directional couple of pattern；The multiplexer manufacturing process is simple, may be used Three-dimensional waveguide or optical fiber form multiplexer；Directly and fused fiber splice there can be wider service band；But such multiplexer passes The non-linear and decaying of defeated channel is larger, and design does not account for the high difference modes group delay problem of step index fiber yet；This The pattern cross-interference issue that a little problems and low effective refractive index difference band come can all make system signal restore difficulty and increase.And it is big Effective area, pure silicon dioxide fibre core transmission channel have the characteristics that low decaying, low splice loss, splice attenuation, low nonlinearity, help to improve The optical signal to noise ratio of system, realize large capacity, long distance transmission, obtained scientific worker concern [12Makovejs S, Roberts C,Palacios F,et al. Record-low(0.1460dB/km)attenuation ultra-large effective area optical fiber for submarine applications[C].Optical Fiber Communications Conference and Exhibition (OFC),2015:1-3；13Hirano M,Yamamoto Y,Kawaguchi Y.Low-Loss and Low-Nonlinearity Pure-Silica-Core Fiber for C-and L-band Broadband Transmission[J].Journal of Lightwave Technology,2016,34(2): 321-326]。

Utility model content

This patent proposes a kind of three pattern mode division multiplexing device of low crosstalk graded--index planar waveguides, realizes gradually changed refractive index Type distribution, low crosstalk, low-loss, large effective module scene product, low nonlinearity coefficient, high coupling efficiency, wide service band three moulds Formula lacks mould multiplexing；Easy to implement and Transmission Fibers same type multiplexer transmission channel is to effectively improve coupling efficiency, reduce and melt Connect loss；Lack mould transmission for fiber optic communication, Front-haul lacks mould transmission functionization and provides support.

Technical solution is used by present patent application solves its technical problem：

The three pattern mode division multiplexing device of low crosstalk graded--index planar waveguides that this patent proposes, including 3 identical transmission letters Road forms, one of them is main transmission channel；20 μm of transmission channel radius, transmission channel fibre core and cladding index are poor 0.0015, cladding index 1.442524；The refractive index of channel core center to covering changes in gradation type；Consider pattern Channel couples length, channel separation and coupling efficiency situation of change, pattern LP01 directly inputs main transmission channel, to avoid mould The problem that coupling loss is big, device size is big caused by formula LP01 channel couples length is long；Pattern LP11a and LP11b channel It being individually positioned on the main transmission channel cross section direction x and y, channel length is 28mm, and the spacing with main channel is 5 μm, With the high coupling efficiency for ensureing multiplexer and reasonable coupling length.It should using full-vector finite element method and beam propagation method research Few mould multiplexer characteristic.

The advantageous effect of present patent application is：

1. transmission channel realizes low-loss using the pure silicon dioxide fibre core of large effective area, effectively reduce and pure titanium dioxide Silicon fibre core lacks mould Transmission Fibers splice loss, splice attenuation, improves coupling efficiency；

2. realizing low difference modes group delay using gradation type index distribution；

3. effective refractive index difference is more than 0.5 × 10 between pattern^-3With the low crosstalk between Assured Mode；

4. the effective area of arbitrary patterns channel is all higher than 6 times of standard single-mode fiber, nonlinear factor is far below mark The nonlinear factor of quasi-monomode fiber；

5. in 1400nm-1700nm wave bands, multiplexer coupling efficiency is better than -0.512dB；In C-band, multiplexer is arbitrary The maximum value of mode channel coupling efficiency and minimum value difference are no more than 0.051dB, and flat characteristic is presented；

6. the multiplexer characteristic makes it lack in fiber optic communication, mould transmits, Front-haul lacks the fields such as mould transmission with wide Application prospect.

Description of the drawings

Fig. 1 is in 1550nm wavelength, along linear polarization mode horizontal polarization direction, the coupling length of 3 kinds of spatial model channels With the variation of two channel separations.Solid line with asterisk, circle and four boxes in Fig. 1 indicates LP01, LP11a and LP11b mould respectively The coupling length of formula channel with channel separation variation；

Fig. 2 is 5 μm of channel spacing, along linear polarization mode horizontal polarization direction, 3 kinds of spatial model channel couples efficiency with entering Penetrate the variation of optical wavelength.Solid line with asterisk, circle and four boxes in figure is respectively LP01, LP11a and LP11b mode channel Coupling efficiency with lambda1-wavelength variation；Wherein (a) figure corresponds to 1400nm to 1700nm wave-length coverage situations, and (b) figure corresponds to C-band situation；

Fig. 3 is the structural schematic diagram of multiplexer；Wherein figure (a) is overall structure, and figure (b) and (c) are multiplexer master respectively The structural schematic diagram in transmission channel the cross section directions x and the directions y；

Fig. 4 is 3 kinds of mode channel coupling efficiencies of multiplexer with the variation of lambda1-wavelength.In figure band asterisk, circle and The solid line of four boxes is respectively variation of LP01, LP11a and LP11b mode channel coupling efficiency with lambda1-wavelength；Wherein scheme (a) corresponding 1400nm to 1700nm wave-length coverage situations, the corresponding C wave band situations of figure (b).

Specific implementation mode

The technical solution of the utility model patent application is described in detail with reference to embodiment and attached drawing, but protection domain is not It is limited to this.

1 Fig. 1 of embodiment is in 1550nm wavelength, along linear polarization mode horizontal polarization direction, the coupling of 3 kinds of spatial model channels Close variation of the length with two channel separations.Solid line with asterisk, circle and four boxes in Fig. 1 indicate respectively LP01, LP11a and The coupling length of LP11b mode channels with channel separation variation.Fig. 1 shows the coupling length of 3 kinds of mode channels with letter Road spacing increases and increases.Along linear polarization mode horizontal polarization direction, the coupling length of LP01 mode channels becomes with channel separation Change faster, slightly slow, the coupling length of LP11a mode channels of the opposite LP01 variations of coupling length variation of LP11b mode channels It varies less；The coupling length difference of three kinds of spatial model channels is larger；When transmission channel spacing is identical, LP01 mode channels Coupling length is maximum, and the coupling length of LP11a mode channels is minimum, and the coupling length of LP11b mode channels is less than LP01 patterns Channel is much larger than LP11a mode channels；Along linear polarization mode vertical polarization, the coupling length and coupling of LP01 mode channels It closes efficiency and is equal to the corresponding horizontal polarization direction of the mode channel；The coupling length of LP11a (LP11b) mode channel and coupling Efficiency corresponds to the horizontal polarization direction of LP11b (LP11a) mode channel.The research is the channel separation of selection of multiplexer, channel Length and each pattern and the relative position of main transmission channel provide guarantee.

Fig. 2 is 5 μm of channel spacing, along linear polarization mode horizontal polarization direction, 3 kinds of separate space mode channel coupling efficiencies With the variation of lambda1-wavelength.Solid line with asterisk, circle and four boxes in figure is respectively LP01, LP11a and LP11b pattern Channel couples efficiency with lambda1-wavelength variation；Wherein (a) figure corresponds to 1400nm to 1700nm wave-length coverage situations, (b) figure Corresponding C-band situation.(a) figure in Fig. 2 it is found that in 1400nm to 1700nm wave-length coverages, imitate by the channel couples of 3 kinds of patterns Rate is superior to -0.089 dB, and flat characteristic is presented；The coupling efficiency of 3 kinds of mode channels is insensitive to wavelength change；LP01、 The highest coupling efficiency of LP11a and LP11b mode channels is respectively -0.002dB, -0.009dB and -0.002dB, minimum difference For -0.023dB, -0.092dB and -0.085dB；The average coupling efficiency of LP01, LP11a and LP11b mode channel be respectively- 0.010dB, -0.039dB and -0.034dB；The high coupling efficiency of 3 kinds of mode channels shows low damage when all channel independences Consume characteristic；In same incident light wave strong point, the coupling efficiency of LP01, LP11a and LP11b mode channel is by lambda1-wavelength shadow The degree of sound is close.(b) Tu Ke get in Fig. 2, any point in C-band, the coupling efficiencies of 3 kinds of mode channels is superior to- Flat characteristic is presented in 0.011dB, independent channel coupling efficiency.In entire 1400nm to 1700nm wavelength variation ranges, LP01 and LP11a (LP11b) mode channels LP01 and LP11b (LP11a) pattern letter in the coupling efficiency and Fig. 2 of vertical polarization Road is consistent in the coupling efficiency of horizontal polarization direction.

Fig. 3 is the structural schematic diagram of multiplexer；Wherein figure (a) is overall structure, and figure (b) and (c) are multiplexer master respectively The structural schematic diagram in transmission channel the cross section directions x and the directions y.The multiplexer is made of 3 identical transmission channels, wherein One is main transmission channel.Consider mode channel coupling length, channel separation and coupling efficiency situation of change, pattern LP01 directly inputs main transmission channel, big, the device ruler to avoid the long caused coupling loss of pattern LP01 channel couples length Very little big problem；Pattern LP11a and LP11b channel is individually positioned on the main transmission channel cross section direction x and y, channel length It is 28mm, the spacing with main channel is 5 μm, and arrangement above can guarantee that the high coupling efficiency of multiplexer and rationally coupling are grown Degree.

Fig. 4 is 3 kinds of mode channel coupling efficiencies of multiplexer with the variation of lambda1-wavelength.In figure band asterisk, circle and The solid line of four boxes is respectively variation of LP01, LP11a and LP11b mode channel coupling efficiency with lambda1-wavelength；Wherein scheme (a) corresponding 1400nm to 1700nm wave-length coverage situations, the corresponding C-band situation of figure (b).(a) chart is bright in Fig. 4, LP01 patterns The coupling efficiency of channel reduces with the increase of lambda1-wavelength；The coupling efficiency of LP11a and LP11b mode channels is in C-band Higher, coupling efficiency reduces outside C wave bands with increaseing or decreasing for lambda1-wavelength；LP11a and LP11b mode channels Coupling efficiency variation it is consistent；The coupling efficiency of LP11a and LP11b mode channels is identical in independent channel and multiplexer；It is multiple With device in 1400nm to 1700nm wave-length coverages, LP01, LP11a and LP11b mode channel coupling efficiency highest is respectively- 0.044dB, -0.009dB and -0.009dB, minimum is respectively -0.512dB, -0.092dB and -0.089dB；In Fig. 4 (b) For figure it is found that in C-band, LP01, LP11a and LP11b mode channel coupling efficiency highest are respectively -0.132dB, -0.009dB With -0.009dB, minimum is respectively -0.183dB, -0.011dB and -0.011dB；LP01, LP11a and LP11b mode channel are flat Equal coupling efficiency is respectively -0.156 dB, -0.010dB and -0.048dB；The maximum value of all mode channel coupling efficiencies and most Small value difference is no more than 0.051dB, and flat characteristic is presented.

In short, the three pattern mode division multiplexing device of low crosstalk graded--index planar waveguides that this patent proposes realizes mode channel folding Penetrate the distribution of rate gradation type, low crosstalk, low-loss, large effective area, small nonlinear factor, high coupling efficiency, wide service band spy Property；In 1400nm-1700nm wave bands, multiplexer coupling efficiency is better than -0.512dB；In C-band, multiplexer arbitrary patterns letter The maximum value of road coupling efficiency and minimum value difference are no more than 0.051 dB, and flat characteristic is presented.This to mode division multiplexing device into One step research is of great significance, and lacks mould transmission for fiber optic communication, Front-haul lacks mould transmission functionization and provides support.

It should be pointed out that specific implementation mode is the more representational example of this patent, it is clear that the skill of this patent Art scheme is not limited to the above embodiments, and can also have many variations.Those skilled in the art define public affairs with this patent Written description open or according to file is undoubted to be obtained, and this patent scope of the claimed is considered as.

Claims (1)

1. a kind of three pattern mode division multiplexing device of low crosstalk graded--index planar waveguides, characterized in that including 3 identical transmission channels Composition, one of them is main transmission channel；20 μm of transmission channel radius, transmission channel fibre core and cladding index poor 0.0015, Cladding index is 1.442524；The refractive index of channel core center to covering changes in gradation type；Pattern LP01 directly inputs master Transmission channel；Pattern LP11a and LP11b channel is individually positioned on the main transmission channel cross section direction x and y, and channel length is equal For 28 mm, the spacing with main channel is 5 μm.