Highly Birefringent Honeycomb Photonic Bandgap Fibre

A new structure of highly birefringent honeycomb photonic bandgap fibres (PBGFs), including an elliptical air hole in its solid core, is proposed and analysed by using full vectorial plane wave expansion method. From the numerical results it is confirmed that the proposed PBGF has birefringence of the order of 10^-3. Moreover, there are two single-polarization single-mode ranges at varying normalized wavelength, in one of which only the slow-axis mode exists, and in the other only the fast-axis mode exists, which has not been achieved in index-guiding photonic crystal fibres so far.