Fiber Bragg Grating Inscription in Highly Asymmetric HiBi PCF with a Low Intensity UV CW laser

The transmission properties of Photonic Crystal Fibers (PCFs) can be tailored with unprecedented flexibility. This flexibility can be exploited to overcome current shortcomings of Fiber Bragg gratings (FBGs) for sensing applications. However, FBG inscription in PCFs is very challenging because the internal micro-structure of airholes in the PCF cladding does not favour conventional FBG inscription techniques. In this report we show that it is feasible to use a low energy UV-Argon laser and a phase mask to inscribe FBGs in a highly birefringent Ge-doped core PCF, optimized for grating inscription.