Abstract: A single core bidirectional optical device having a light emitting element that is provided on the terminal of one optical fiber and makes light incident to the optical fiber, and a light receiving element for receiving light of the optical fiber, comprises a wavelength multiplexing/demultiplexing coupler that is provided on an optical axis of light incident to and emitted from the optical fiber and includes therein wavelength separating film for separating the light to light of one side and light of another side for every wavelength; a light emitting element provided on the direction of the light of the one side which is separated by the wavelength multiplexing/demultiplexing coupler; and a light receiving element provided on the direction of the light of the other side which is separated by the wavelength multiplexing/demultiplexing coupler.

Abstract: In an optical transceiver of the invention, a magnet-free Faraday rotator is arranged on an optical axis between a light-emitting part and an end face of an optical fiber, and after rotating a plane of polarization of light of a first wavelength output from the light-emitting part, the light is input to a polarization dependent wavelength-separating film as P-polarized light. The polarization dependent wavelength-separating film has a characteristic of passing the P-polarized light of the first wavelength, and reflecting S-polarized light of the first wavelength and light of a second wavelength output from the optical fiber. As a result it is possible to provide a single-core bidirectional optical transceiver that can be shortened in overall length, with a low loss and without affecting transfer characteristics.