Nippon Electric Co., Ltd.

Nec Corporation

Kouichi Minemura

Katsumi Emura

Minoru Shikada

Shigetoki Sugimoto

Teiji Uchida

An optical heterodyne detection pulse receiving system operates such that the light from a local oscillator and from a pulse modulated optical carrier are mixed, and a signal having an intermediate (difference) frequency is extracted. Pulse signal regeneration is effected by demodulating the intermediate frequency signal while maintaining a positive integer multiple of one-half the intermediate frequency signal synchronized with the repeating frequency of the pulse signal.

Optical heterodyne detection pulse receiving system and method

There is disclosed a bidirectional optical fiber transmission system. This system includes first and second light transmitter-receiver sets and a single strand of optical fibers. The light transmitter-receiver sets each comprise (a) a light receiver, (b) a light transmitter whose light source is a light emitting diode, and (c) means to isolate downstream and upstream light from each other. The optical fibers connect the light-transmitter-receiver sets through the light isolating means. The emission spectra of the light emitting diodes at least partly overlap each other and the isolating means have wavelength pass bands which do not substantially overlap each other.

Bidirectional optical fiber transmission system

A light branching device includes a light-focusing transmission body having a refractive index which decreases in proportion to the square of the distance from the plane of its optical axis, and two end faces perpendicular to the optical axis and a substantial light path length equal to an integral multiple of approximately one-half of the pitch at which the light propagates. The ends of a plurality of optical fibers are disposed adjacent to the end faces so that light emanating from one of the optical fibers is dispersed primarily in a plane parallel with the optical axis plane and impinges upon the end of at least one of the other optical fibers for transmission therethrough.

Growing community of inventors

Tokyo, Japan

Kouichi Minemura