Methodology for in situ Characterisation of a Highly Birefringent Photonic Crystal Fibre for Supercontinuum Generation

A novel methodology for precisely determining the eigenaxes and effective twist of a solid-core polarisation maintaining fibre with a slightly elliptical effective core in an experimental setup with an ultrashort pulse laser is presented. This geometrical identification relies on experimental modal analysis and by utilising an incoherent ultrashort optical pulse fragment measurement and modelling procedure, and is a prerequisite for precise measurements and characterisation of this class of fibres. This orienting method is applied in the study of low threshold and temporally and polarisation stable supercontinuum generation in ~2m length of photonic crystal fibre, utilizing a modelocked Ti:Sapphire laser.