Abstract: An optical module receives light traveling through an optical fiber in two ways. A coupler is provided in a case member and is attached to an end surface of a ferule having the optical fiber. The coupler allows light of a first wavelength to pass therethrough along a first optical axis of the optical fiber and reflects light of a second wavelength so that reflected light travels along a second optical axis perpendicular to the first optical axis. A light emitting element is provided so as to be located on one of the first and second optical axes. A light receiving element is provided so as to be located on the other one of the first and second optical axes.

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 receptacle module includes an optical module unit including therein an optical device and carrying a sleeve, a ferrule holder fitted into the sleeve and holding therein a ferrule, a frame member mounted on the ferrule holder, and an adapter unit mounted on the frame unit and accepting an external optical plug, wherein the ferrule holder having an engagement part for engagement with the frame at a location away from the optical device with respect to an engagement part of the frame member used for engagement with the adapter unit.

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 waveguide device having an optical waveguide chip, first and second adapters, and an optical fiber plug. The optical waveguide chip has an optical waveguide structure having a connection end, and an end surface of the chip is flush with the connection end. The first adapter is fixed to the chip, and has an outer surface set in predetermined positional relation with the connection end. The second adapter has an inner surface including a first region and a second region, and is detachably mounted to the first adapter so that the outer surface of the first adapter comes to close contact with the first region. The optical fiber plug has an optical fiber having an excitation end and a ferrule in which the optical fiber is inserted and fixed. The optical fiber plug is detachably mounted to the second adapter so that the outer surface of the ferrule comes to close contact with the second region.

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.