Objective
Development and application of modelling methods for key optical passive and active waveguide components for use in fibreoptic telecommunication;
Implementation of experimental techniques that offer the capability to measure accurately and reproducibly the properties and parameters of novel active and passive photonic components incorporating optical waveguide structures.
The idea is to organise and manage an open collaborative effort in Europe in the fields of modelling photonic components and of their experimental characterisation.
Current status
Specialists in the field of photonic components get together and define problem sets of common interest to the participating institutions. The problems are in the fields of modelling and measurements of structures and devices that have a potential to be used in future fibreoptic communications. Back in their laboratories, the scientists apply their own specific methods to handle the problems and communicate the results to the co-ordinating member of the particular Working Group (WG). Three WGs are operational : on lasers ; on passive waveguide components ; and on non-linear effects. The results are discussed in meetings about every six months where possible difficulties are analysed in depth. The outcome of successfully solved problems is presented in workshops organised by COST and in international conferences andis published in refereed scientific journals. The work is supervised and co-ordinated by the Management Committee (MC) of the Action and reported to the COST TCT.
In WG1 different simulation tools developed or in use in the participating laboratories are applied to modelling key static and dynamic characteristics of lasers for communication systems. The exercise aims at comparing the various approaches as used in laser models and has demonstrated a convergence of results, after several round-robins for the same structure. In addition, other common exercises are in progress aiming at the comparison of the results of modelling with measurements and at the study of methods that allow derivation of structural values from physical measurements. The devices under study are usually DFB and DBR lasers and semiconductor optical amplifiers (SOAs) that are fabricated in some of the participating university and industrial laboratories. The round-robins are accompanied by regular meetings where the results are openly discussed and possible deviations are analysed.
In the research laboratories participating in the WG2, a broad collection of modelling tools have been developed for optical waveguides and waveguide devices such as two- and three-dimensional scalar and vectorial mode solvers and beam propagation methods (BPM) for real and complex refractive indices. A representative benchmark test of various beam-propagation algorithms covering those based on the Fourier transform (FT), finite difference (FD), and finite element (FE) methods has recently been carried out. Since then, comparative modelling calculations of total-internal-reflection mirrors in InP and tapered waveguide structures have been performed. The latter ones are of growing importance for reducing coupling loss between semiconductor waveguides and fibres. Very recently, a novel benchmark test for BPM methods for waveguides with complex refractive indices has been formulated and is now running. It is based on peculiar properties of a double-layer slab waveguide with balanced loss and gain. This work contributes to better understanding of modal behaviour in optical waveguides with complex refractive indices, such as those containing metal electrodes, detectors, (linear) amplifiers etc.
The main goal of the collaboration in WG3 is to establish a set of measurements able to characterise the non-linearity of SOAs and to define criteria for the experiments. A round-robin on Four Wave Mixing (FWM) interlaboratory comparative measurements was started. The SOAs operate around 1550 nm and are donated by two participating industrial laboratories. In particular, parameters of importance for the system implementation are now in investigation, such as FWM-efficiency, noise characteristics and polarisation sensitivity.
Work planned
Following the success of the co-operative research in the Actions on optical communications in the past, COST 240 plans to continue the efforts to preserve and enhance the open, uncomplicated spirit of the forum for work between the participating scientists and institutions and is thus planning to launch at the end of the decade new activities that will continue well into the first decade of the next century.
Research in this domain will evolve from the existing and develop new COST activities on semiconductor components, with emphasis on simulation and measurements of devices and associated sub-systems that have the inherent potential to meet the growing demands of systems and networks. The goal is the exploration of the possibilities offered by advanced devices to increase the efficiency, flexibility and operability of future networks. Devices would be studied that can improve the performance of transmitters, receivers, routers and regenerators in relation to advanced passive and active fibres aiming at an overall increase of performance in systems and networks. Investigation is planned of physical effects that can bring added insight into the working of components in linear and non-linear regimes, and research will be carried out on new ways for light generation, transmission and amplification. Such devices might be, for example, advanced lasers, laser and receiver arrays, filters, amplifiers, frequency converters, multiplexers and switches.
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Call for proposal
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8925 Schlieren
Switzerland