UV trimming of arrayed-waveguide grating wavelength division demultiplexers

The transmission peak wavelength of a fibre-pigtailed arrayed-waveguide silica-on-silicon grating (AWG) demultiplexer has been shifted using a 248 nm excimer laser without penalties in crosstalk or insertion loss. The transmission peak shift and shape were monitored while trimming. A wavelength shift of 0.77 nm (94 GHz) was achieved while keeping a crosstalk of –25 dB for 400 GHz channel spacing and an insertion loss < 7 dB.