Photonic bandgap fibres

Photonic bandgap fibres have a cladding that is carefully structured to reject light of certain frequencies and propagation constants. The light is therefore confined to a core that can even be made of air, something that is not possible in conventional fibres that guide by total internal reflection. Since the first one was made 10 years ago, bandgap fibres have been demonstrated that guide light with low loss, low optical nonlinearity, strong gasphase interactions and useful transmission spectra. This tutorial will review the various designs and applications of bandgap fibres, and consider how their bandgaps arise.