65 dB dynamic range 2.8 microseconds switching speed variable fiber-optic attenuator

For the first time a >65 dB dynamic range fast 2.8 microseconds fiber-optic variable optical attenuator (VOA) is proposed and demonstrated by using a single bulk-acousto-optic device. The unique double pass optical design eliminates intrinsic acousto-optic interaction-based Doppler shift while a center-path positioned halfwave plate (HWP) greatly reduces polarization dependent loss (PDL) to 0.03 dB. The current VOA insertion loss is <2.5 dB with a demonstrated 1520-1600 nm operation.