Crosstalk reduction in a 10-GHz spacing arrayed-waveguide grating by phase-error compensation

The crosstalk in arrayed-waveguide grating multiplexers with a channel spacing of 10 GHz is reduced by compensating for the phase errors after fabrication. We used the thermooptic effect realized with a thin-film heater and the photoelastic effect obtained with amorphous silicon film, respectively, for dynamic and static phase-error compensation. These two methods were applied to confirm the principle and to realize a stable, stand-alone device, respectively. We have achieved a crosstalk of less than -35 dB for the TE polarization mode in a 16 x 16, 10 GHz-spacing arrayed-waveguide grating by using these two phase-error compensation techniques. Static phase-error compensation results in a stable multiplexer which features a low crosstalk of less than -30 dB for one of the two polarization modes of all the channels without any external control equipment.