Optical Fibre Communications

Backgound

Optical fibre communications has become an indispensable part of the network infrastructure for global communications supporting the internet. Optical fibres are the main carriers of the heavy traffic of core networks and Dense Wavelength Division Multiplexing (DWDM)combined with optical amplifiers have fueled the development and installation of Terabit/s fibre optic systems.

The design of optical fibres capable of supporting DWDM systems requires refractive index control in order to achieve the desired dispersion properties of optical fibres. Designs with low (near zero) dispersion and low dispersion slope are necessary over the entire useful wavelength band. Techniques which allow the prediction of dispersion and complete characterization of optical fibres have been known, but the inverse problem, of synthesizing an optical fibre refractive index profile from dispersion is not an easy problem and not well known.

The project is to develop techniques for designing optical fibres and other fibre optic components such as fibre gratings and other optical filters such as gain equalizers for optical amplifires and WDM filters and dispersion compensators.

A means for achieving the above is via use of the Equivalent Circuit approach which we have developed in the past for optical fibre characterisation. This is a fundamental and most powerful technique for modeling waveguides which allows description in terms of equivalent electric circuits and allows coupling into and use of DSP techniques for the design of optical fibres and components.

Project Objectives:

1. To develop the Equivalent Circuit (EC) technique for field plotting in optical fibres

2. To develop the EC technique for prediction of dispersion

3. To carry out the inverse problem: The synthesis of the refractive index profile from the fields.

4. The synthesis of the refractive index profile from dispersion.

5. The design of optical filters using DSP techniques.

6. To design fibre optic gratings from reflection spectra.

7. To design other components based on the EC and optical DSP techniques.