Multichannel operation of AOTF switches: reducing channel-to-channel interaction

An acoustooptic tunable filter (AOTF) can be used as a multichannel wavelength-routing switch; however, switching efficiency decreases and the switched wavelength channels shift toward each other when neighboring channels are selected simultaneously. We explain the cause of this behavior and show how to reduce the degradation in switch characteristics using a combination of passband flattening and counterpropagating acoustic waves. >