The last part of the thsis presents a novel fast response digital variable optical attenuator . this device is driven by two electromagnetic driving units rather not stepper motors . a wide attenuation ( 40db ) was fully digitized and can be set by a certain number of driving pulses 论文最后针对现有数字可调光衰减器均由步进电机驱动，体积庞大，造价高昂且速度缓慢的缺点，利用微反射单元设计了一种高速数字式可调光衰减器。
