Abstract: An optical device includes an optical amplifier that optically amplifies incident light, a first isolator that is arranged on an input stage of the optical amplifier and inputs the incident light to the optical amplifier, and a second isolator that is arranged on an output stage of the optical amplifier and receives input of incident light that has been optically amplified by the optical amplifier. The first isolator inputs, to the optical amplifier, first linearly-polarized incident light that is converted from randomly-polarized incident light and that has been transmitted. The second isolator, when reflected light of the first linearly-polarized incident light that has been optically amplified by the optical amplifier is input from a reverse direction, converts reflected light of the first linearly-polarized incident light to reflected light of second linearly-polarized light that is orthogonal to the reflected light of the first linearly-polarized incident light.

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.

Abstract: It is possible to reduce the size of a magneto-optical device, increase the speed of optical control, simplify power supply structure and its control, and maintain a Faraday rotation angle in an arbitrary state even after shut-off of the excitation current. The magneto-optical device includes a magnetic yoke (10) made of a high-permeability magnetic material, the magnetic yoke including a tabular portion (16) and four pillar portions (18) protruding from one side of the tabular portion (16), a coil (12) wound on each of the pillar portions, and a magneto-optical element (14) arranged in an open-magnetic-circuit region surrounded by the end portions of the four pillar portions. A magnetic field obtained by a coil is applied to the magneto-optical element.

Abstract: It is possible to reduce the size of a magneto-optical device, increase the speed of optical control, simplify power supply structure and its control, and maintain a Faraday rotation angle in an arbitrary state even after shut-off of the excitation current. The magneto-optical device includes a magnetic yoke (10) made of a high-permeability magnetic material, the magnetic yoke including a tabular portion (16) and four pillar portions (18) protruding from one side of the tabular portion (16), a coil (12) wound on each of the pillar portions, and a magneto-optical element (14) arranged in an open-magnetic-circuit region surrounded by the end portions of the four pillar portions. A magnetic field obtained by a coil is applied to the magneto-optical element.

Abstract: An optical module is provided with a ferrule an optical fiber which penetrates a center thereof along an axis direction of the ferrule, a member inserted with the ferrule, a sealed container connected to the member and having an optical system which optically couples to the optical fiber, and a resin portion encapsulating the member and the sealed container. A communication path includes a first communication passage between the ferrule and the member, a space where the optical system and the optical fiber confront each other, and a second communication passage between the ferrule and the member, where the first and second communication passages are mutually independent.

Abstract: An optical module is provided with a ferrule an optical fiber which penetrates a center thereof along an axis direction of the ferrule, a member inserted with the ferrule, a sealed container connected to the member and having an optical system which optically couples to the optical fiber, and a resin portion encapsulating the member and the sealed container. A communication path includes a first communication passage between the ferrule and the member, a space where the optical system and the optical fiber confront each other, and a second communication passage between the ferrule and the member, where the first and second communication passages are mutually independent.

Abstract: An optical module includes a ferrule having a slope end surface and supporting an optical fiber penetrated therethrough, a photodetector attached to the slope end surface and optically coupled directly with the optical fiber, a module substrate supporting the ferrule, and a resin package covering the ferrule so that an end of the ferrule protrudes from the resin package.

Abstract: An optical fiber assembly includes a substrate carrying an optical device and a ferrule having a cutout surface, wherein the substrate is mounted on the ferrule such that a principal surface of the substrate engages a corresponding flat cutout surface of the ferrule. Further, an optical module that uses such an optical fiber assembly is disclosed.

Abstract: A constricted portion (14) is formed on an optical fiber (6) composed of a core (2) and a clad (4), and one or two belt-like conductive layers (20) elongated in a longitudinal direction of the optical fiber (6) are provided on a surface of the constricted portion (14). With the structure, the device functions as a polarizer which removes a polarized light component having a polarization plane perpendicular to the conductive layers (20). The optical fiber polarizer is suitably inserted in and used with an optical transmission line of an optical communication system and is also suitable for use as a component of an optical isolator.