Optically Switched Arrayed Waveguide Gratings Using Phase Modulation

This paper reports a theoretical analysis of novel optically switched arrayed waveguide gratings (AWG) based on a silicon-on-insulator (SOI) platform using phase modulation. The phase modulation can be achieved by integrating optical phase modulators across the grating arms, incorporating four-way splitters and combiners to reduce the thermal optic effect. The phase modulator operates by injecting the free carriers to change the refractive index in the guiding region, hence allowing different wavelengths to route to different output waveguides. Also, with appropriate absorption caused by the free carriers, optical switching can be performed. We demonstrate by computer simulation the optical and electrical characteristics of the devices using a three-dimensional (3-D) beam propagation method (BPM) (optical) and the two-dimensional (2-D) device simulation package SILVACO (electrical). The drive current necessary for switching the wavelength in question by one waveguide distance is approximately 0.17 mA/ mum and the attenuation factor is approximately 1 dB. These devices are useful for broad application in both wavelength-division multiplexing (WDM) networks and photonics integrated circuits