US Patent 9804340 Optical fiber connector capable of switching connection polarity

An optical fiber connector according to the present disclosure includes an inner housing, a first outer housing and a second outer housing. The inner housing has a first wall, a second wall, a third wall and a fourth wall, wherein the first wall faces the third wall and connects with the second and fourth walls. The first outer housing is positioned to surround the inner housing. The second outer housing is positioned to surround the inner housing and engage the first outer housing. A key arm extends from the second outer housing and is configured to position on the first wall or the third wall of the inner housing. When the inner housing is inserted into an optical fiber adapter, the key arm is inserted into the key recess of the optical fiber adapter.