Trench-Assisted Multicore Fiber with Single Supermode Transmission and Nearly Zero Flattened Dispersion

A trench-assisted multicore fiber (TA-MCF) with single-supermode transmission and nearly zero flattened dispersion is proposed herein. By adding a simplified microstructure cladding with only one ring of low-index inclusions on the basis of the multicore fiber, the microstructure cladding and mode-coupling mechanism were jointly employed into the TA-MCF to modulate light transmission. This guarantees that the TA-MCFs had sufficient capability for wideband dispersion management when only pure, germanium-doped, and fluorine-doped silica glass with low index differences were chosen to form the TA-MCF. Analyses also revealed that the TA-MCFs have the merits of shorter cut-off wavelength and flatter-top optical intensity distribution compared with traditional multicore fibers. After the investigation of the structural parameters’ influences on the dispersion of the fundamental supermode, two TA-MCFs with single-supermode transmission and nearly zero flattened dispersion were designed. For the seven-core TA-MCF, the dispersion varying from −0.46 to 1.35 ps/(nm·km) in the wavelength range of 1.50 to 2.04 μm, with bending loss as low as 0.085 dB/km and 35-mm bending radius at 1550 nm was achieved with index difference less than 0.015. The TA-MCFs proposed herein have the advantages of being a quasi-single material, with an all solid scheme and simplified structure.

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Comparative crosstalk performance analysis of different configurations of heterogeneous multicore fiber

Journal of Optical Communications ◽

10.1515/joc-2019-0091 ◽

2020 ◽

Vol 0 (0) ◽

Author(s):

Umar Farooque ◽

Rakesh Ranjan

Keyword(s):

Refractive Index ◽

Mode Coupling ◽

The Other ◽

Heterogeneous Multicore ◽

Coupled Mode ◽

The Core ◽

Bending Radius ◽

Multicore Fiber ◽

The Impact ◽

Core Pitch

AbstractIn order to select the heterogeneous multicore fiber (MCF) configuration with ultra-low crosstalk and low peak bending radius, comparative crosstalk analysis have been done for the three possible core configurations, namely, Configuration 1 - different refractive index (R.I.) and different radius, Configuration 2 - different R.I., and Configuration 3 - different radius. Using the coupled mode equation and the simplified expressions of mode coupling coefficient (MCC) for different configurations of heterogeneous cores, the crosstalk performance of all the heterogeneous MCF configurations along with the homogeneous MCF have been investigated analytically with respect to core pitch (D) and fiber bending radius (${R}_{b}$). Further, these expressions of MCC have been extended to obtain the simplified expressions of MCC for the estimation of crosstalk levels in respective trench-assisted (TA) heterogeneous MCF configurations. It is observed from the analysis that in Configuration 1, crosstalk level is lowest and the rate of decrease in the crosstalk with respect to the core pitch is highest compared to the other configurations of heterogeneous MCF. The values of crosstalk obtained analytically have been validated by comparing it with the values obtained from finite element method (FEM) based numerical simulation results. Further, we have investigated the impact of a fixed percent change (5%) in the core parameters (radius and/or R.I.) of one of the core of a homogeneous MCF, to realize the different heterogeneous MCF configurations, on the variations in crosstalk levels, difference in the mode effective refractive index of the core 1 and core 2 ($\Delta {n}_{eff}={n}_{eff1}-{n}_{eff2}$), and the peak bending radius (${R}_{pk}$). For the same percent variations (5%) in the core parameters (radius and/or R.I.) of different configurations of cores (Config. 1-Config. 3), Config. 1 MCF has highest variation in $\Delta {n}_{eff}$ value compared to other configurations of MCF. Further, this highest variation in $\Delta {n}_{eff}$ value of Config. 1 MCF results in smallest peak bending radius. The smaller value of peak bending radius allows MCF to bend into smaller radius. Therefore, Configuration 1 is the potential choice for the design of MCF with smaller peak bending radius and ultra-low crosstalk level compared to the other configurations of SI-heterogeneous MCF.

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Design and Analysis of Trench-Assisted Low-Bending-Loss Large-Mode-Field-Area Multi-Core Fiber with an Air Hole

Photonics ◽

10.3390/photonics8070251 ◽

2021 ◽

Vol 8 (7) ◽

pp. 251

Author(s):

Renjie Jia ◽

Yudong Lian ◽

Yulei Wang ◽

Zhiwei Lu

Keyword(s):

Communication Systems ◽

Structural Parameters ◽

Practical Implementation ◽

Mode Field ◽

Bending Loss ◽

Optical Communication Systems ◽

Bending Radius ◽

Core Fiber ◽

Field Area ◽

Air Hole

In this paper, a trench-assisted low-bending-loss large-mode-field-area multi-core fiber with air hole is proposed, which can achieve dual-mode transmission. The influence of structural parameters on fiber performance is analyzed systematically, and the structure of the trench, with a lower refractive index than the cladding, is also analyzed and optimized. By adjusting the structural parameters, the effective mode field area of the fundamental mode can reach 2003.24 um2 at 1550 nm, and when the bending radius is 1 cm, the bending loss is 2.57 × 10−3 dB/m. The practical implementation of the proposed fiber is feasible using existing fabrication technology and is applicable to the transmission of large-capacity optical communication systems and high-power lasers.

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Dependence of resonant light transmission properties of a subwavelength slit on structural parameters

Optics Express ◽

10.1364/oe.17.011026 ◽

2009 ◽

Vol 17 (13) ◽

pp. 11026 ◽

Cited By ~ 4

Author(s):

K. Lindfors ◽

L. Lechner ◽

M. Kaivola

Keyword(s):

Light Transmission ◽

Structural Parameters ◽

Transmission Properties ◽

Subwavelength Slit

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Robust Nonlinear Control of Mode-Coupling-Based Vibrations by Using High-Gain Observer and Sliding-Mode Controller

Journal of Dynamic Systems Measurement and Control ◽

10.1115/1.4048356 ◽

2020 ◽

Vol 143 (2) ◽

Author(s):

Lyes Nechak

Keyword(s):

Nonlinear Control ◽

Mode Coupling ◽

Sliding Mode ◽

High Gain ◽

State Observer ◽

Sliding Mode Controller ◽

Coupling Mechanism ◽

Robust Nonlinear Control ◽

High Gain Observer ◽

Nonlinear State

Abstract This paper is dedicated to the robust nonlinear control of friction-induced vibrations (FIV), more particularly those generated according to the mode-coupling mechanism. A nonlinear scheme which consists of a sliding-mode controller implemented by using a high-gain state observer is proposed. The main objective is to suppress or mitigate the generated vibrations by taking into account of the nonlinearities and uncertainties inherent to friction systems. Hence, this study proposes the analysis of the closed-loop performances of the high-gain observer-based sliding-mode controller when used for the active control of vibrations issued from the mode-coupling mechanism. Based on numerical simulations, the proposed controller has shown suitable performances distinguished from an effective suppress of the generated vibrations. Otherwise, it is shown that the gain of the used nonlinear state observer must be tuned in order to ensure a suitable compromise between the robustness level of the performances with respect to parameter uncertainty and the robustness level with respect to the measurement noise.

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Effect of Structure Parameters on Polycal Wire Rope Isolator Stiffness-Damping Characteristics

Shock and Vibration ◽

10.1155/2019/4525798 ◽

2019 ◽

Vol 2019 ◽

pp. 1-10 ◽

Cited By ~ 1

Author(s):

Shaowu Tu ◽

Xiaofeng Lu ◽

Xiaolei Zhu

Keyword(s):

Prediction Models ◽

Structural Parameters ◽

Wire Rope ◽

Diameter Ratio ◽

Element Analysis ◽

Damping Characteristics ◽

Bending Radius ◽

Pitch Length ◽

The Wire ◽

Wire Strand

Wire rope isolators are mainly used to isolate vibration and protect precise equipment. However, the issue of regulation of vibration isolators taking into account the nonlinearity of their characteristics was poorly understood in the modern literature. In this paper, the influence of structural parameters (diameter ratio and lay pitch of the single strand, and lay pitch and bending radius of the wire rope) on stiffness-damping characteristics of the Polycal WRI was investigated by the simplified finite element analysis method. The stiffness and damping prediction models including structural parameters and material properties were established. The results showed that the stiffness-damping characteristics were the best; when the diameter ratio of wire strand was 1.1, the inside layer wire pitch length was 6 times the diameter of the wire strand, the outside layer wire pitch length was 11 times the diameter of the wire strand, the pitch length of the wire rope was 7.5 times its diameter, and the bending radius was equal to 46.5 mm. The errors of the prediction for prestiffness and softened stiffness were within 5%, and the errors of prediction for the energy dissipation coefficient were within 10%.

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