Abstract: An optical modulator in which an optical signal is input from one side of a package, includes in the package, a chip that optically modulates the optical signal and in which an input waveguide and an output waveguide of the optical signal are led to mutually different destinations each being one end of the chip facing the one side of the package and a side surface of the chip orthogonal to the one end of the chip; an input optical system coupled to the input waveguide of the chip; and an output optical system coupled to the output waveguide of the chip.

Abstract: An optical module includes a substrate on which an optical waveguide is provided; a housing that houses the substrate and includes a through path arranged on a side wall of the housing so as to extend in a direction that crosses the optical waveguide; a ferrule that houses an end portion of an optical fiber; and an optical path conversion element that is fixed on the ferrule, that is fixed on an end surface of the substrate on the end portion side of the optical waveguide, and that has a size smaller than a width of the substrate and a width of the ferrule along a longitudinal direction of the substrate. The end portion of the optical waveguide is arranged at a position close to the through path of the housing relative to a central portion in a width direction of the substrate.

Abstract: An optical module includes a substrate on which an optical waveguide is provided; a housing that houses the substrate and includes a through path arranged on a side wall of the housing so as to extend in a direction that crosses the optical waveguide; a ferrule that houses an end portion of an optical fiber; and an optical path conversion element that is fixed on the ferrule, that is fixed on an end surface of the substrate on the end portion side of the optical waveguide, and that has a size smaller than a width of the substrate and a width of the ferrule along a longitudinal direction of the substrate. The end portion of the optical waveguide is arranged at a position close to the through path of the housing relative to a central portion in a width direction of the substrate.

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: An optical module includes a first level detecting part having a semi-transparent structure and receiving a light signal emitted from a light-emitting element, a second level detecting part receiving the light signal which penetrates through the first level detecting part and passes through an optical filter, and a control part controlling an operation temperature of the light-emitting element on the basis of electric signals output from the first and second level detecting parts.

Abstract: An optical transmitting/receiving module including a light emitting element, a light receiving element, a transmitting optical communication line for transmitting an optical signal, a receiving optical communication line for receiving an optical signal, and a single aspherical lens for coupling the transmitting light emitted from the light emitting element to the transmitting optical communication line and for coupling the receiving light emergent from the receiving optical communication line to the light receiving element. The light emitting element is arranged so that the center line of a beam of the transmitting light emitted from the light emitting element is inclined with respect to the optical axis of the lens. With this arrangement, the optical transmitting/receiving module can be reduced in size.

Abstract: A compact, low-cost combined transmitting/receiving optical communications module, which is suitable for use in a TCM system and which is capable of normal operation over a particularly wide temperature range in optical communications equipment, is provided. The optical transmitting/receiving section for this purpose has a laser diode which outputs a transmitted optical signal, a combined monitor/receiving photodiode which not only monitors the optical output signal from the laser diode during a transmitting period, but also receives the input optical signal from the transmission path during the receiving period, and an optical mixer/divider which performs transmitting/receiving mixing and dividing between the transmission path, the laser diode, and the photodiode.

Abstract: An optical parallel receiving module receives optical signals transmitted in parallel in a plurality of channels by using optical fibers. The optical parallel receiving module includes photo-electric conversion elements for converting received signals which are electric signals as received signals, limiter amplifiers for comparing the received signals and a threshold level, and data decision circuits for recognizing data at a timing in every period of received data using a reference clock.

Abstract: An optical module for two-way transmission includes a lens for converging a received light from an optical fiber, and a photodiode for sensing the converged received light. A laser diode outputs a transmitted light, and a prism shifts the optical path of the transmitted light converged by the lens, and inputs the transmitted light to the optical fiber.

Abstract: A compact size optical multiplexer and demultiplexer module. The optical multiplexer and demultiplexer module includes a multiplexing and demultiplexing film disposed on an end surface of a waveguide substrate, having an optical waveguide formed thereon, on which surface an input and output end of the optical waveguide appears. The multiplexing and demultiplexing film transmits a light beam of wavelength .lambda..sub.1 and reflects a light beam of wavelength .lambda..sub.2. A first optical fiber is disposed such that a light beam with the wavelength .lambda..sub.1 propagated therethrough is coupled to the input and output end of the waveguide substrate after being transmitted through the multiplexing and demultiplexing film and the second optical fiber is disposed such that a light beam with the wavelength .lambda..sub.2 propagated therethrough is coupled to the first optical fiber after being reflected by the multiplexing and demultiplexing film. A light beam with the wavelength .lambda..sub.