Photonic crystal fibres (PCF), also known as micro-structured fibres or holey fibres, constitute a new class of optical fibres offering significant new possibilities and functionality within a diverse range of applications including optical communications, fibre lasers and amplifiers, nonlinear fibre devices, fibres for high power transmission and new types of fibre-based sensor devices. There are two types of PCFs: in index-guided PCFs the core area is solid and the light is confined to a central core by a modified form of total internal reflection. In bandgap-guided PCFs the core is hollow, and light is guided by the photonic bandgap (PBG) effect. Indexguided PCFs have already proven their capability for specific telecom applications, while PBG PCFs show extremely promising features, such as the possibility to propagate with a linear attenuation below the Rayleigh limit owing to air guiding, together with much reduced nonlinearities. In addition filling the hollow core with specific gasses can give PBG-MOFs a decisive advantage for sensing purposes.

The scope of WG1 encompasses characterisation of PCFs and PCF-based components through measurement and modelling of their linear and nonlinear properties and experimental investigations and numerical simulations of light propagation in PCFs. WG1 focus on fibres showing an interest for optical processing (highly nonlinear) and for sensing (hollow core). Topics of particular interest for this WG are:

• Measurement of linear parameters of PCFs: attenuation, bending loss, mode field diameter, cut-off wavelength, chromatic dispersion, birefringence, polarisation mode dispersion.
• Measurement of nonlinear properties of MOFs: nonlinear coefficient, 4-wave mixing, modulational instability, Raman scattering, Brillouin scattering, c(2) properties.
• Theoretical analysis (modelling) of index-guided PCFs.
• Experimental studies and numerical simulations of nonlinear propagation in PCFs.
• Experiments on spectroscopy using gas-filled hollow core fibres.
• Characterisation of specialty PCFs: i.e. rare earth ion-doped fibres, multicore fibres, fibre gratings etc.