MEMS Attenuator is a voltage-driven component based on a micro-electro- mechanical system (MEMS) chip. The MEMS chip consists of an electrically movable mirror on a silicon support. A voltage applied to the MEMS chip causes the mirror to rotate, which changes the coupling of light between the input and output fibers of the MEMS Attenuator. Because of its excellent feature, it is successfully applied in military project.