Analysis and design of a novel leaky YIG film guided wave opticalisolator

A guided wave optical isolator using a four layered leaky yttrium iron garnet (YIG) waveguide with a YIG guiding layer is proposed and analyzed through a transfer matrix formulation. The dependence of isolation characteristics on different waveguide parameters are discussed. It is shown that for four layered structures an isolation ratio of about 24 dB can be achieved with YIG films having large gyrotropy. It is also shown that by replacing the single guiding YIG film with multilayers of YIG with compensated walls and proper permittivity, high isolation ratio can be achieved even with currently available YIG films having low gyrotropy     

Dynamic Routing and Wavelength Assignment Using Cost Based Heuristics in WDM Optical Networks

Dynamic routing and wavelength assignment problem in optical networks is a two-step problem that is influenced by the choice of a successful optimal path selection and wavelength assignment. Proper selection techniques reduce the number of wavelengths required in the network and thereby improves traffic grooming. Heuristic algorithms and integer linear programming models help in selection of route and wavelength separately. Hence, the computation time is large which makes the system slow. A cost function is computed which uses independent parameters in the network for the selection of route and wavelength for a call. The heuristic reduces computation time by combining the search of route and wavelength to be assigned. In addition, the network performance is analyzed with and without alternate routing along with proposed heuristics. The selection of proper route and wavelength finding technique is very essential since it improves the grooming factor of the network thereby allowing more traffic support by the network. Our objective is to investigate and propose a cost based heuristics for dynamic traffic routing and wavelength Assignment in WDM optical networks. For this we plan to develop cost functions and heuristics to compute the route and wavelength assignment strategy. Here, our objective is to reduce the computation time for selection of route and wavelength assignment strategy by weighted cost function. The function has to include network parameters for its processing. Our work provides an overview about DRWA by applying cost based heuristics in WDM networks. This paper explains the proposed cost function and its applications in line with selection of independent parameters. The details of other functions like cost function formulation, hop-based route assignment, available wavelength based route assignment, mathematical analysis of proposed cost function are also explained. Results and discussions based on the findings are presented.

     

A new magnetostatic wave delay line using YIG film

We have proposed a delay line of microstrip type consisting of a microstrip line fabricated on a composite substrate of two yttrium iron garnet films separated by a gadolinium gallium garnet layer. The dispersion relations are derived assuming magnetic walls at the edges of the strip. Experiments are carried out at S band with nonuniform magnetic field. Insertion loss less than 25 dB with large delay time more than 800 ns is observed experimentally. The experimental results on delay line characteristics are briefly discussed with theory     

Explanation of polarisation dependence of differential phase shift in two-mode elliptic-core fibre strain gauges

An appropriate elliptic-core fibre theory is applied to model the differential phase shift between the first- and second-order modes observed in recent experiments on two-mode elliptic-core fibres subjected to longitudinal strains. The theory provides an explanation of the polarisation dependence of the stretching delta l/sub 2 pi / required to produce a 2 pi differential phase shift between the two modes as a function of wavelength for both polarisations.<>     

Si3N4 – SiO2 Based Curve Slot Waveguide for High Confinement Factor and Low Mode Effective Area along with Biosensing Application

Silicon - A Si3N4 - SiO2 based curve slot optical waveguide is demonstrated comprehensively for guiding and sensing applications. Design parameters are optimized to provide high confinement factor...