Resonantly enhanced nonlinearities in rare earth doped fibres and waveguides

The use of rare-earth dopants for all-optical switching is of interest because of the very low pump powers required to achieve full switching. In addition, the ease with which rare-earth ions can be incorporated into silica based hires and waveguides makes them ideally suited for the fabrication of fibre compatible components. The principal disadvantages of this type of nonlinearity are that the relaxation times are characteristically slow (similar to ms), and relatively long interaction lengths (similar to 1m) are required to achieve phase changes of the order of pi. In this presentation, an overview of the work being carried out in Australia will be given, concentrating on the techniques developed to minimise the relaxation times and power.length products of these nonlinearities.