Photosensitisation of silica planar lightwave interleaver for phase error correction

Photosensitivity locking with a 248 nm KrF laser was applied to a hydrogen-soaked silica planar waveguide to improve the refractive index response for post-laser phase trimming of an interleaver. A more than tenfold photosensitivity enhancement was stabilised by annealing the interleaver circuit at 150°C for 24 h. The interleaver channel isolation was improved from 6 to 18 dB by balancing the interferometer phase errors with a modest KrF laser dose