Abstract: A light transmission module is disclosed, having a light receiving element module, in which a photodiode and a coupling portion between the photodiode and a first optical fiber are hermetically sealed, and a light emitting element module, in which a laser diode driven by an electric signal and a coupling portion between said laser diode and a second optical fiber are also hermetically sealed. A two-sided print board is provided, on the two sides of which electric circuits for a transmitting system and a receiving system are mounted. The electric circuits for the transmitting and receiving circuits are; isolated electrically from each other, and are sealed in one body by molds, and accommodated in cases, together with the light receiving element module and the light emitting element module.

Abstract: In a device for coupling optically a light source with an optical transmission path, the present invention interposes an optical transmission path structure at the center of the distance between them in order to improve the optical coupling efficiency. The optical transmission path structure consists of a plurality of light transmitting elements arranged so that the light from the light source is received by the structure as incident light and is sent out therefrom as outgoing light at an outgoing angle which is equal to the angle of incidence. The light transmitting elements are arranged in parallel with the optical path of the light emitted from the light source and according to this arrangement, the system of the present device becomes equivalent to a system in which the positions of the light source are located at points of .+-.l.sub.1 from the light outgoing surface of the optical transmission path structure.

Abstract: An opto-electric transformation connector is provided, which can be used, as if it were an electric connector, without consideration of optical transmission of devices connected therewith, in a connecting system for connecting different devices by means of optical fibers. The connector includes an electronic circuit board, on which not only a light emitting element for transmitting optical signals and a light receiving element for receiving optical signals are disposed, but also a driving circuit for driving the light emitting element and an amplifier circuit for amplifying the light signals received by the light receiving element are mounted.

Abstract: An optical switch having a small number of optical connections includes a substrate in which are provided a first light path for conducting optical signals and a second light path consisting of a photosensitive element and light emitting element in pairs. An optical fiber cable is interrupted by the substrate, and optical signals in the fiber cable are transmitted through the first light path or intervened by an electrical system through the second light path in response to the switching movement of the substrate.