Nippon Telegraph and Telephone Public Corporation

Ocean Cable Co., Ltd.

Yasuji Murakami

Nobuyuki Yoshizawa

Hidefumi Mori

Tatsuo Izawa

Koushi Ishihara

Kiyoshi Funaki

Nobuo Shimizu

A submarine optical fiber cable includes inner and outer dams at suitable intervals for limiting water flow in the cable. The outer dams are formed in a space between inner and outer metal tubes of a pressure resisting sheath of the cable, and the inner dams are formed in the inner tube in which an optical fiber unit is enclosed. Each dam is made of a sticky compound or a jelly of plastics resin which is loaded at the dam position. The cable is also provided with a scale which represents distance from one end of the cable.

Submarine optical fiber cable with dam means

Halides of Si and Ti, B, P, or Ge and oxygen or steam are introduced into a reaction vessel and heated in a vapor phase to form fine glass particles by oxidation or hydrolysis. The fine glass particles are deposited on a substrate. The deposited fine glass particles are heated and vitrified into a transparent glass layer, which is etched to form a core having a desired pattern by a reactive sputter etching process using Freon gas. The core is coated by a clad. In a waveguide thus formed, the cross sectional configuration and dimensions of the core layer and the refractive index difference are precisely controlled. The waveguide is manufactured with good reproducibility. The fabrication method is suitable for mass production of waveguides. An expansion coefficient transient layer is provided between the core layer and the substrate to prevent a crack in the waveguide. The glass softening temperature of the cladding layer is set lower than that of the core layer, so that the cross sectional configuration and dimensions of the core layer is unchanged against the heat in the vitrification process of the cladding layer. The refractive index is reduced in the vicinity of the boundary between the core and clad to prevent the loss of light due to light scattering on the core side faces.

Method of making glass waveguide for optical circuit

Growing community of inventors

Mito, Japan

Yasuji Murakami