Dispersion characteristics of novel class multi-clad dispersion shifted hollow core fibers for WDM optical systems

The design and analysis of multiple-clad hollow core dispersion-shifted fibers have been presented in this paper. Fiber profiles have been designed consisting of a central core that is hollow and outer cladding is silica. The novel refractive index profile has multi-clad for enhanced optical characteristics. Optical fibers with two or more claddings are required for dispersion shifting, dispersion flattening, and other specialized applications. Thus, the hollow core fiber shows the zero dispersion at 1550 nm wavelength. These hollow core fibers have potential application in WDM optical systems

Modelling of simply supported circular diaphragm for touch mode capacitive sensors

This paper describes the power series solution for modelling of the simply supported circular diaphragm deflection under uniform load. The parameters such as touch point pressure and touch radius are defined. Moreover, these parameters are also computed by the algorithm proposed in the paper. Therefore, the power series solution can be applied for touch mode operation

Finite element method analysis of propagation in a non magnetic coupled waveguide structure having α-power refractive index profile

The work presented in the paper is a numerical study of a waveguiding component. The structure studied is a coupler consisting of three closely-coupled weakly-guiding one-dimensional waveguides. The refractive index profile of the coupler has been allowed to vary arbitrarily. The scalar finite element method (FEM) has been used to separately extract the TE and TM modes supported by this coupler and propagate them along the structure using a beam propagation method (BPM). We excite structure with Eigen mode profile which can be well approximated by Gaussian shape pulse. The effect of waveguide separation has been well demonstrated by using an example. The Crank-Nicolson (CN) scheme has been used to stabilize the propagation and transparent boundary conditions (TBC) which have been used to absorb energy leaked by the waveguides to the outer boundaries. The work’s main finding is that the coupling period of the structure can be changed by altering the index profile of the middle waveguide; step-, parabolic- and triangular-profile distributions have been studied and compared. In FEM analysis we have used the variable discretization step (δ) for the better accuracy of the results

Asymmetric Group Velocity Dispersion and Pulse Distortion in a Uniform Fiber Bragg Grating

In a uniform fiber Bragg grating, if the input signal is a Gaussian pulse the dispersion is zero near center wavelength and becomes appreciable only near the band edges and side lobes of the reflection spectrum. However for chirped Gaussian pulses, group velocity dispersion and the reflected light must become asymmetric. Here the chirped Gaussian pulses can be treated as a symmetric but nonuniform input signal. The present paper describes that for the case of symmetric Gaussian pulse, the group velocity dispersion and pulse distortion remain symmetric however strong the grating may be. On the other hand both tend to be more asymmetric for the case of strong grating while the input signal is symmetric with nonuniform shape

Modeling of single mode optical fiber having a complicated refractive index profile by using modified scalar finite element method

A numerical method based on modified scalar finite element method (SC-FEM) is presented and programmed on MATLAB platform for optical fiber modeling purpose. We have estimated the dispersion graph, mode cut off condition, and group delay and waveguide dispersion for highly complicated chirped type refractive index profile fiber. The convergence study of our FEM formulation is carried out with respect to the number of division in core. It has been found that the numerical error becomes less than 2 % when the number of divisions in the core is more then 30. To predict the accurate waveguide dispersion characteristics, we need to compute expression (d^2 (Vb))/(dV^2 ) numerically by the FEM method. For that the normalized propagation constant b (in terms of β) should be an accurate enough up to around 6 decimal points. To achieve this target, we have used 1 million sampling points in our FEM simulations. Further to validate our results we have derived the higher order polynomial expression for each case. Comparison with other methods in calculation of normalized propagation constant is found to be satisfactory. In traditional FEM analysis a spurious solution is generated because the functional does not satisfy the boundary conditions in the original waveguide problem, However in our analysis a new term that compensate the missing boundary condition has been added in the functional to eliminate the spurious solutions. Our study will be useful for the analysis of optical fiber having varying refractive index profile

Optimization of Multi-Energy Systems for Efficient Power-to-X Conversion

This paper reviews the work in the areas of optimization and efficiency enhancement of multi-energy systems (MES) for power-to-X conversion. The first study delves into the deployment of Power-to-Hydrogen (PtH2) within district-scale MES, emphasizing the role of PtH2 in achieving zero operational CO2 emissions, especially in systems with high renewable energy generation. The study also highlights the significance of heat pump efficiency, battery capital cost, and lifetime in influencing PtH2 implementation. The second investigation focuses on the integration of energy strategies for the transport and building sectors. It introduces a multi-objective optimization model that considers both sectors, aiming to minimize costs and life-cycle emissions. The findings suggest a potential transition from internal combustion engines to battery electric vehicles and a shift from gas boilers to heat pumps, leading to substantial emission reductions by 2050. Lastly, the third research explores the potential of power-to-gas (P2G) technology in enhancing the integration of renewable energy. By coordinating P2G with CO2-based electrothermal energy storage (ETES), the study demonstrates a significant improvement in the recovery efficiency of surplus wind power. Collectively, these studies underscore the importance of optimizing MES for sustainable and efficient energy conversion

Analytical And Numerical Study Of Propagation In Optical Waveguides And Devices In Linear And Nonlinear Domains

The objective of this thesis is to study of optical effects, arising in the form of non-uniform waveguide structure, complicated refractive index profiles or due to pulse propagation in dense wavelength division multiplexing (DWDM) optical communication systems. These effects are important and critically influence the performance of DWDM optical systems. A comprehensive survey of current literature on optical effects due to nonuniform optical structure and nonlinear optical effects is first done, showing their advantages and disadvantage in optical communication systems. A survey on methods of optical waveguide analysis is also done. The main contribution has been made to three main aspects of the problem : Accurate analysis of uniform/non-uniform optical waveguides with arbitary refractive index profiles Pulse propagation and distortion in DWDM Raman amplification systems. Use of non-uniform FBG to compensate for pulse distortion We study several existing analytical techniques developed so far for analyzing the mode of non-uniform optical waveguide structures. Later, we verify the analytical results by finite element method (FEM). The convergence study is also carried out. A new computational technique is proposed modifying the finite element method to analyze complex refractive index profiles required for the analysis, namely single mode step index profile, multi clad fiber, W -profile, chirp profile etc. An accuracy of 10−4 in the calculation of propagation constant/eigen-value is demonstrated. Dispersion characteristics of optical fibers w.r.t. different profile parameters is evaluated. A modification to scalar BPM is proposed and applied to study the effects of inhomogeneities along the propagation direction. The applicability and accuracy of the method is tested using integrated optic waveguide devices, namely, graded index slab waveguide. The proposed BPM uses Fourier decomposition of the transverse field. Coupled mode theory (CMT) of optical waveguides in non-homogeneous optical medium is applied to study the interaction of lightwaves propagation together such as in a DWDM system. The BPM results is verified by CMT. The inhomogeneous waveguide theory is extended to study pulse propagation in DWDM optical communication system. Nonlinear optical effects are an important aspects of DWDM systems with fiber Raman amplifier. Finite difference time domain (FDTD) method is necessary to study these nonlinear optical effects as other conventional methods are not suitable here. Here, we discuss DWDM optical communication systems due to nonlinearity in the form of SRS effect. In case of FRA, we study the various kinds of fiber profile design parameters, for the purpose to achieve and extend the flat gain bandwidth over the EDFA window. We also propose and study, a new bi-directional optical fiber transmission scheme with various constraints, using Raman amplification process with and without pump depletion. Our scheme, provides an advantage like high SNR, low pump induced noise, for long-haul communication link. We find that, there is a quite significant crosstalk and power coupling among the dense DWDM channels but earlier discussed BPM fails to account for possible interference effects among the channels. To reduce the harmful nonlinear optical effects like four wave mixing (FWM), we need to deploy a high chromatic dispersion fiber, which will ultimately lead to high pulse walk-off rate among the DWDM channels; hence for high bit rate long haul systems, walk-off effect can not be ignored. Application of FDTD provided an improved insight into the effect of GVD on stimulated Raman scattering crosstalk than different modulation techniques and line codes. It is shown through analysis that pulse walk-off phenomena may distort the data asymmetrically; especially for case of wide-band DWDM transmission system. Hence, the pulse walk-off effect should be considered in future systems containing optical amplifier. It is shown, that large walk-off rate may reduce the crosstalk among DWDM channels but tends to increase the asymmetric pulse distortion. Data may lose due to high walk-off effect. We also investigate channel addition/removal process in DWDM fiber Raman amplifier. We also demonstrate that the pulse walk-off effect tends to lead significantly to positive chirp for higher frequency channels. This feature can be exploited to overcome the chromatic dispersion effects in DWDM transmission systems. Pulse walk-off induced chirp, can be compensated by using the nonuniform fiber Bragg grating (NUFBG). The CMT due to periodic perturbation of the circular cylindrical waveguide structures is applied here. Here, we discuss the function of fiber Bragg grating as a transmission versus reflecting grating filter. We also discuss, FBG application to gain flattening of an EDFA window as well as how the group velocity dispersion (GVD) will be affected with bandwidth and coupling coefficient. We develop a new analytical technique to estimate the bandwidth of FBG based optical system. Finally, we investigate the dispersion compensation properties, pulse distortion, peak reflectivity analysis in uniform/non-uniform FBG due to an uniform/non-uniform incoming signal. More complicated refractive index profile can significantly reduce the GVD as well as side lobes intensity. Dispersion characteristic due to an arbitrary refractive index profile is discussed in details for the case of non-uniform FBG. Thus, we concluded that wide band DWDM optical communication system need to closely take into account various inhomogeneities and nonlinearities of optical fibers w.r.t. wave and pulse propagation

Optical Networking

Telecommunication networks based on optical fiber technology have become a major information transmission system with high capacity optical fiber links encircling the globe in both terrestrial and undersea installation. At present there are numerous passive and active optical devices within a light wave link that perform complex networking functions in the optical domain, such as signal restoration, routing, and switching. Along with the need to understand the functions of these devices comes the necessity to measure both components and network performance and to model and simulate the complex behavior of reliable high capacity networks. This chapter presents the fundamental principles for understanding and applying these issues. This chapter is primarily about TCP/IP network protocols and Ethernet network architectures, but also briefly describes other protocol suites, network architectures, and other significant areas of networking. It explains in simple terms the way networks are put together, and how data packages are sent between networks and subnets, along with how data is routed to the Internet.</jats:p