Patent attributes
An optical multiplexer/demultiplexer includes: first to n-th demultiplexed light input/output portions; a multiplexed light input/output portion; second to n-th interference film filters; and first to n−1-th mirrors. The first to n-th demultiplexed light input/output portions are disposed on a single plane and correspond to light having a single wavelength. The second to n-th interference film filters are disposed in front of the second to n-th demultiplexed light input/output portions. The first to n−1-th mirrors are disposed in front of the first demultiplexed light input/output portion and in front of the n−1-th interference film filters. Light from the first demultiplexed light input/output portion strikes the first to n−1-th mirrors and the second to n-th interference film filters and is input to the multiplexed light input/output portion. Light output from the multiplexed light input/output portion strikes the second to n-th interference film filters and first to n−1-th mirrors.