the National Key Research and Development Program of China(Grant No.2019YFB2203504);Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB43000000);the Natural Science Foundation of Anhui Province,China(Grant No.1908085QF274)。
A four-stage cascaded variable optical attenuator(VOA)with a large attenuation range is presented.The VOA is based on a Mach–Zehnder interferometer(MZI)and fabricated in a silica-based planar lightwave circuit(PLC)pl...