First demonstration of thermal poling in holey fibres

Summary form only given. Holey fibres (HF), also commonly known as photonic crystal fibres, offer exciting new possibilities for the development of single material waveguides with unique properties. Many of these properties are relevant to nonlinear applications. To date the main focus has been on third-order /spl chi//sup (3)/ nonlinear effects, however many of these novel properties are also of great relevance to /spl chi//sup (2)/ based phenomena. For example our calculations show that endlessly single mode HF designs allow the overlap between interacting modes at widely different wavelengths to be optimised and can be used to improve second harmonic generation (SHG) efficiencies relative to conventional poled fibres. Moreover the greater flexibility for broadband waveguide-dispersion control can also be used to significantly increase the associated phase-matching bandwidth. Despite these attractions it has been an open question to date as to whether thermal poling, which relies upon ionic migration, could be applied to such complex air:glass structures; we demonstrate that it can be.