Effect of On-Axis Dip in Refractive-Index Profile on the Cutoff Frequency of Modes of Few Mode Fibers: A Numerical Approach
TL;DR: In this paper, the normalized cutoff frequencies of the linearly polarized (LP) modes of a graded-index few mode fiber have been calculated as a function of profile shape parameters using a simple numerical method.
Abstract: The normalized cutoff frequencies of the linearly polarized (LP) modes of a graded-index few mode fiber have been calculated as a function of profile shape parameters using a simple numerical method. The effect of refractive-index dip on these cutoff frequencies and on the order of appearance of these modes has been investigated. The presence of dip causes an increase in the cutoff V values of all the modes, and the maximum shift in the cutoff V value is found to be even 20% for some modes. The order of appearance of some modes also gets drastically affected.
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TL;DR: In this article, two parameter variational fields for the LPl1 modes of a graded index few-mode fiber have been proposed and the accuracies of the results have been calculated by comparison with the exact results obtained from the numerical solution of the scalar wave equation.
Abstract: Two parameter variational fields for the LPl1 modes of a graded index few-mode fiber have been proposed. Using these, the propagation constant, the normalized group delay and the normalized dispersion parameter have been calculated for few representative modes. The accuracies of the results have been calculated by comparison with the exact results obtained from the numerical solution of the scalar wave equation. As expected, the two parameter fields give better accuracies than the single-parameter fields available in the literature. Furthermore, it is observed that the accuracy decreases for higher order LPl1 modes. Thus, these fields may be used in few-mode fiber-based photonic devices, which utilize lower order LPl1 modes.
5 citations
TL;DR: In this article, the authors investigated the Kerr nonlinear optical processes in the case of a single-mode trapezoidal index fiber based on recently formulated and appropriate Marcuse-type relations for spot size in terms of normalized frequency corresponding to such fiber having various aspect ratios.
Abstract: We investigate the Kerr nonlinear optical processes (NOPs) in the case of a single-mode trapezoidal index fiber based on recently formulated and appropriate Marcuse-type relations for spot size in terms of normalized frequency corresponding to such fiber having various aspect ratios. With the help of these relations, we have analyzed the maximum NOP in these fibers having prospective the merits of tight light confinement in the subwavelength diameter waveguiding region. The comparative investigation reveals that the aspect ratio having a value of 0.7 is the most promising candidate for maximum optical nonlinearity, constructional convenience, and less diffraction. The analysis should be attractive for system users as a ready reference.
5 citations
TL;DR: In this article, the fiber tip based hyperbolic microlens coupling efficiency of circular core trapezoidal index single mode fiber and a laser diode was theoretically studied and the corresponding analytical expressions were formulated considering ABCD matrix for hyper bolic micro-lens following paraxial approximation and also Gaussian field distributions are considered for both the source and the fiber.
3 citations
TL;DR: In this article, the authors use the splice loss measurement technique in absence and presence of angular misalignment and report a simple and accurate method to predict the unknown aspect ratio of a supplied circular core trapezoidal index single mode fiber.
3 citations
TL;DR: In this paper, a detailed variational analysis of single-mode trapezoidal index fiber to investigate its propagation characteristics involving two simple approximations of fundamental mode is presented, and it is shown in respect of computation of normalized field that the single parameter variational function having Gaussian and modified Bessel variations in the core and cladding, respectively, is more accurate in comparison with the Gaussian function over a wide range of values of normalized frequency and aspect ratio.
Abstract: A detailed variational analysis of single-mode trapezoidal index fibre to investigate its propagation characteristics involving two simple approximations of fundamental mode is presented. It is shown in respect of computation of normalized field that the single parameter variational function having Gaussian and modified Bessel variations in the core and cladding, respectively, is more accurate in comparison with the Gaussian function over a wide range of values of normalized frequency and aspect ratio. Also, it predicts the propagation characteristics, more accurately, than the Gaussian function from variational and recently reported Marcuse-type formulations. Further, in terms of such range of values, a complete formulation of variational parameter for the Gaussian-modified Bessel function is prescribed for ready reference to the system users to predict the modal field and propagation characteristics.
3 citations
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01 Dec 2007TL;DR: In this article, the authors present a detailed analysis of planar optical waveguide and a step-index fiber model for optical fiber communication and demonstrate the properties of a step index fiber.
Abstract: 1. Introduction 2. Basic optics 3. The optical fiber 4. Ray analysis of planar optical waveguide 5. Graded index optical fibers 6. Material dispersion 7. Planar waveguides 8. Characteristics of a step-index fiber 9. Graded Index fibers 10. Waveguide dispersion and design considerations 11. Sources for optical fiber communication 12. Detectors for optical fiber and communication 13. Fiber optic communication system design 14. Optical fiber Amplifiers 15. Dispersion compensation and chirping phenomenon 16. Optical solitons 17. Single-mode fiber optic components 18. Single mode optical fiber sensors 19. Measurement methods in optical fiber: I 20. Measurement methods in optical fibers: II 21. Periodic interactions in waveguides 22. Ray equation in Cartesian coordinates 23. Ray paths 24. Leaky modes.
843 citations
TL;DR: In this paper, the authors describe the variety of fiber devices enabled by few-mode fibers-fibers that typically support two to four modes with suitably tailored dispersive properties.
Abstract: In-fiber devices enable a vast array of critical photonic functions ranging from signal conditioning (amplification, dispersion control) to network management (add/drop multiplexers, optical monitoring). These devices have become mainstays of fiber-optic communication systems because they provide the advantages of low loss, polarization insensitivity, high reliability, and compatibility with the transmission line. The majority of fiber devices reported to date are obtained by doping, designing, or writing gratings in the core of a single-mode fiber (SMF). Thus, these devices use the fiber only as a platform for propagating light-the device effect itself is due to some extraneously introduced material or structure (dopants for amplification, gratings for phase matching, etc.) There exists another, relatively less explored degree of freedom afforded by fibers-the ability to copropagate more than one mode. Each mode may have a uniquely defined modal dispersion and propagation characteristic. In this paper, we will describe the variety of fiber devices enabled by few-mode fibers-fibers that typically support two to four modes with suitably tailored dispersive properties. We will show that the unique dispersive properties of various modes, in conjunction with the ability to couple between them with gratings, leads to devices that offer novel solutions for dispersion compensation, spectral shaping, and polarization control, to name a few.
140 citations
TL;DR: Polarimetric and two-mode differential interferometric schemes incorporated in an elliptical core fiber are able to resolve strain and temperature simultaneously with resolutions of 10 /spl mu/m/m and 5/spl deg/C, respectively.
Abstract: Polarimetric and two-mode differential interferometric schemes incorporated in an elliptical-core fiber are able to resolve strain and temperature simultaneously with resolutions of 10 /spl mu/m/m and 5/spl deg/C, respectively. A technique, based on the evaluation of the condition number of a matrix, is shown to be useful in evaluating comparative merits of multiparameter sensing schemes. The determinant of the beat length matrix is expressed in terms of mode propagation constants, and a method for designing specialized fibers suitable for simultaneous measurement of strain and temperature is proposed. Experimental results for four fibers are presented and cross-sensitivity issues are discussed. >
124 citations
TL;DR: In this paper, the authors demonstrate simultaneous dispersion and dispersion-slope compensation of 240 km of NZDSF from 1530 to 1560 nm using a higher-order-mode-fibre compensator.
Abstract: The authors demonstrate simultaneous dispersion and dispersion-slope compensation of 240 km of NZDSF from 1530 to 1560 nm using a higher-order-mode-fibre compensator. With this compensator, 40 Gbits/s operation is achieved across the band, in contrast to a several-nanometre window using commercial DCF.
76 citations
"Effect of On-Axis Dip in Refractive..." refers background in this paper
...In recent years, another kind of fibers, known as few mode fibers (FMFs), have come up with wide applications for dispersion compensation [2, 3] in long-haul transmission systems, sensors [4], modal filters [5], and largely in astronomical telescopes [6, 7]....
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