Polarisation-independent strong Bragg gratings inplanar lightwave circuits

Abstract
High intensity ArF laser irradiation produces Bragg gratings with index modulations > 10–3 in standard germanium-doped silica waveguides without hydrogen loading. A UV-induced birefringence of 2 × 10–4 is used to compensate for the inherent birefringence of the silica waveguides and makes the grating response identical for TE and TM modes.