Compact acoustooptic high-speed variable attenuator for high-power applications

For the first time, a >65-dB dynamic range fast 2.8 μs fiber-optic variable optical attenuator is proposed and demonstrated by using a single bulk acoustooptic device. The unique double-pass optical design eliminates intrinsic acoustooptic interaction-based Doppler shift, while a center path positioned halfwave plate greatly reduces polarization dependent loss to 0.03 dB. The current attenuator's insertion loss is <2.5 dB with a demonstrated 1520-1600 nm operation. Due to its bulk crystal nature, this attenuator can handle high power optical beams.