Author Affiliations
1College of Information Science and Technology, Jinan University, Guangzhou, Guangdong 510632, China2State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou, Guangdong 510275, China3Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, Guangdong 519000, Chinashow less
Fig. 1. Reasons that make the capacity of single-mode fiber approach Shannon limit. (a) Nonlinear Shannon limit
[3]; (b) fiber fuse damage phenomenon
[4]; (c) transmission window of fused-silica fibers, where black region represents the standard optical amplification band
[5] Fig. 2. Comparison of crosstalk between Homo-MCF and Hetero-MCF. (a) Crosstalk of Homo-MCF dependence on bending radius and change of effective index under bending condition; (b) crosstalk of Hetero-MCF dependence on bending radius and change of effective index under bending condition
Fig. 3. Classification of single-mode multi-core fiber based on the assisted structure around core
[20]. (a) Refractive index profile of trench-assisted core; (b) cross-section of trench-assisted multi-core fiber; (c) refractive index profile of air-hole-assisted core; (d) cross-section of air-hole-assisted multi-core fiber; (e) refractive index profile of photonic crystal core; (f) cross-section of photonic crystal multi-core fiber
Fig. 4. Core selection of outer core 1
[42]. (a) Cross-section of a Hetero-TA-7-core fiber; (b)
neff and
Aeff as functions of
r1 and
Δ1 at
λ =1550 nm and
Λ=35
μm for the first outer cores in Hetero-TA-7-core fiber
Fig. 5. Core selection of outer core 2
[42]. (a) Cross-section of a Hetero-TA-7-core fiber; (b)
neff and
Aeff as function of
r1 and
Δ1 at
λ=1550 nm and
Λ=35
μm for the second outer cores in Hetero-TA-7-core fiber
Fig. 6. XT between core 1 and the undetermined core as a function of
neff,q and
K[42], where
neff,p and
neff,q in Eq. (5) are effective indexes of refraction of core 1 and the undetermined core, respectively
Fig. 7. neff and
Aeff as functions of
r1 and
Δ1 at
λ=1550 nm and
λ=35 μm with CSR of center core 2 in Hetero-TA-7-core fiber
[42], where
Fig. 8. Conversion relationship between OAM, CV and LP modes
Fig. 9. Reported inner-depressed step-index few mode fibers with the weak coupling. (a) Inner-depressed step-index 6-LP-mode fiber with the weak coupling
[49]; (b) inner-depressed step-index 7-LP-mode fiber with the weak coupling
[50]; (c) inner-depressed step-index 4-LP-mode fiber with the weak coupling
[51]; (d) inner-depressed step-index 6-LP-mode fiber wi
Fig. 10. Fiber solutions for reducing DMGD between modes. (a) Trench-assisted dual-cladding step fiber with low refractive index
[54]; (b) trench-assisted graded-index fiber with low refractive index
[55]; (c) 0DMGD compensation method to connect positive DMGD fiber (p) and negative DMGD fiber(n) with low refractive index
[57] Fig. 11. OAM mode groups multiplexing transmission system. (a) Low crosstalk and low attenuation ring-core fiber with 4×4 MIMO based OAM multiplexing transmission experiment involving ten wavelengths and eight OAM modes over a distance of 100 km, transmitting 16-Gbaud QPSK signals over all 80 channels
[65]; (b) graded-index multi-mode fiber without MIMO based OAM multiplexing transmission over 2.6 km transmitting 4 OAM mode groups
[Download full size Fig. 12. Cross-section, refractive index distribution and dispersion curves of step-index fiber. (a) Cross-section and refractive index distribution of step-index fiber; (b) dispersion curves of weakly-guiding step-index fiber
[68] Fig. 13. Cross-section, refractive index distribution and dispersion curves of ring-core fiber
[68]. (a) Cross-section and refractive index distribution of ring-core fiber; (b) dispersion curves of weakly-guiding ring-core fiber, when
d/(2
a)=0.20; (c) dispersion curves of weakly-guiding ring-core fiber, when
d/(2
a)=0.25; (d) dispersion curves of weakly-guiding ring-core fiber, when
d/(2
a)=0.30
Fiber | In Ref. [22] | In Ref. [23] | In Ref. [24] | In Ref. [25] | In Ref. [26] | In Ref. [27] |
---|
Cross section of thereported MCFs | | | | | | | Fiber structure | ORS | DRS | HCPS | TLS | New-typeHCPS | SLS | Core number | 12 | 12 | 19 | 22 | 30 | 32 | Core pitch /μm | 37 | 44.6 | 35 | 41 | 30 | 29 | Cladding diameter /μm | 225 | 230 | 200 | 260 | 229 | 243 | Average crosstalk@1550 nm | -32 dB/52 km | <-30 dB/1000 km | -42 dB/1 km | -45 dB/km | -50 dB/9.6 km | <-34.5dB/51.4 km | Loss /(dB·km-1)@1550 nm | 0.199 | 0.186 | 0.227 | 0.21 | — | 0.24 | Transmissioncapacity /(Tb·s-1) | 1010 | 409 | 305 | 2150 | — | — |
|
Table 1. Core arrangement of the reported trench-assisted single-mode multi-core fibers
Fiber | In Ref. [59] | In Ref. [60] | In Ref. [61] | In Ref. [62] | In Ref. [63] |
---|
Cross sectionof strongly-guidedOAM fiber | | | — | | | Refractiveindexdistribution | | | | — | — | OAM modegroup | OAM5,1,OAM5,1,OAM7,1(12 OAMmodes in all) | OAM0,1,OAM1,1,OAM2,1 ,…,OAM7,1 (28 OAMmodes in all) | OAM1,1(2 OAMmodes in all) | OAM+1,1,OAM+2,1,OAM+3,1,OAM+4,1(4 OAMmodes in all) | OAM+1,1,OAM+2,1 (2 OAMmodes in all) | Min Δneff /10-4 | ~1 | 1.1 | 2.1 | ~2 | ~7 |
|
Table 2. Reported OAM strongly-guiding and weakly-coupling ring-core fibers
CV mode | dβ |
---|
H,H | I1 | TE0,1 | 0 | TM0,1 | 2(I1+I2) | H,H(l≥1) | I1- I2 | E,E(l≥2) | I1+I2 |
|
Table 3. Correction of propagation constant for each CV mode
Fiber | Multi-core fiber | Few-mode fiber | Few-mode multi-core fiber |
---|
Fiber fabrication | Mature | A bit complicated | Complicated | Fiber loss | Low | A bit high | High | Crosstalk | Low | Moderate/high | High | Alignment/splicer | Marker assisted/specialfusion splicer | Existing device | Marker assisted/specialfusion splicer | MUX/DEMUX | Space/waveguide/fiber | Space/waveguide/fiber | To be studied | Amplifier | Core/cladding pump | Core/cladding pump | Cladding pump | MIMO-DSP | Ncore×(2×2) | 2Nmode×2Nmode | Ncore×(2Nmode×2Nmode) |
|
Table 4. Comparison among three SDM fiber schemes