Variable optical attenuator

The invention discloses a variable optical attenuator, which comprises double optical fiber head, a PLC assembly, a collimating lens and an MEMS reflector, wherein the PLC assembly has more than two optical paths, at least one optical path is opposite to the other optical paths in light transmission direction, the incident light is emitted to the collimating lens via an input optical fiber of thedouble optical fiber head along an optical path of the PLC assembly in one direction, the collimating lens collimates and outputs the incident light to the MEMS reflector, the MEMS reflector reflectsthe collimated light and emits the light to an output optical fiber of the double optical fiber head along an optical path of the PLC assembly in another direction, each optical path has a one-to-twostructure including an incident port, a main exist port and a branch exit port, the main exit port and the branch exit port output towards different directions, the branch exit port of each optical path is attached with a PD, a