Nippon Hoso' Kyokai

Ngk Insulators, Inc.

Tokin Corporation

Tadasu Ishikawa

Yukihisa Osugi

Yoshinari Kozuka

Kazuhisa Hayeiwa

Mikio Maeda

Hisashi Naka

Michikazu Kondo

Kimiyuki Oyamada

Yozo Utsumi

Shuichi Fujisawa

Yoshiro Sato

Yoshikazu Toba

Kunihara Takizawa

An electric field sensor comprises an electric field sensor head (3) for varying an intensity of a propagating light beam in response to an electric field intensity of an input signal received by a reception antenna (1). The electric field sensor head (3) comprises an incident optical waveguide (9), two phase-shift optical waveguides (10) having a variable refractive index which varies in response to the electric field intensity, an outgoing optical waveguide (11) and, at least one modulation electrode (12) formed in the vicinity of at least one of the two phase-shift optical waveguides (19). The electric field sensor further comprises a circuit element (2) connected between the modulation electrode (12) and the reception antenna (1). The modulation electrode (12) has a thickness not smaller than 1 .mu.m. The modulation electrode (12) may comprise a plurality of split electrodes which are split in a light propagating direction and which are capacitively coupled. The reception antenna (1) is preferably implemented by a low radiation resistance antenna.

Electric field sensor

A first optical waveguide chip has a ceramic substrate and a cover, and the ceramic substrate has a V groove and guide grooves with an optical fiber being fixed in the V groove. A second optical waveguide chip has a ceramic substrate and a cover, and the ceramic substrate has a V groove and guide grooves with an optical fiber being fixed in the V groove. The first and second optical waveguide chips have respective end faces inclined 62.degree. to the direction in which light is propagated through the optical fibers. The first and second optical waveguide chips are positioned by guide pins intimately fitted in the guide grooves.

Optical transmission and reception module having coupled optical

A bidirectional light transmission system comprises a transmitting station having a light source for intensity-modulating a transmission signal, a first light branching portion for branching intensity-modulated light of the light source in a predetermined ratio and a first light receiving portion, and a receiving station having a second light branching portion, a light phase-modulating portion, a light reflecting portion and a second light receiving portion. The transmitting station transmits the intensity-modulated light via a single optical fiber transmission line to the receiving station connected thereto and receives a returned signal returned from the receiving station via the single optical fiber transmission line in the first light receiving portion, and the receiving station branches the transmitted light into first branched light and second branched light in the second light branching portion, phase-modulates at least one of the first branched light and second branched light in the light phase-modulating portion, transmits part of the first branched light and second branched light to the second light receiving portion via the light reflecting portion and simultaneously intensity-modulates reflected part of the first branched light and second branched light as a returned signal in the light phase-modulating portion and the second light branching portion, and returns the returned signal to the transmitting station via the single optical fiber transmission line.

Bidirectional light transmission system and optical device therefor

Growing community of inventors

Tokyo, Japan

Tadasu Ishikawa