초록 ▼

Manufacture of optical fibre preforms. A material such as Si, Ge and B2O3 is evaporated in vacuo into a silica tube and is made to condense therein as a viscous liquid which is then oxidized. The operation may be repeated several times with different materials. In this way the tube is clad from with

Manufacture of optical fibre preforms. A material such as Si, Ge and B2O3 is evaporated in vacuo into a silica tube and is made to condense therein as a viscous liquid which is then oxidized. The operation may be repeated several times with different materials. In this way the tube is clad from within in such a way that the optical index of refraction increases from the periphery inwards. Upon completion of the cladding the tube is collapsed into a rod which is then used for drawing optical fibres.

대표청구항 ▼

In a method of producing a glass preform useful for drawing optical fibres, which comprises forming a system comprising a glass tube having a first end operatively connected to a chamber, charging the chamber with solid silicon, effecting a reduced pressure in the system of 10-8 to 103 microns Hg, h

In a method of producing a glass preform useful for drawing optical fibres, which comprises forming a system comprising a glass tube having a first end operatively connected to a chamber, charging the chamber with solid silicon, effecting a reduced pressure in the system of 10-8 to 103 microns Hg, heating the silicon to a temperature up to 1500°C. so as to evaporate the same while maintaining the reduced pressure in the system, whereby the glass tube is not deformed during the evaporation, externally cooling said tube from the end opposite the first end towards the first end to a temperature at which said silicon condenses as a liquid, thereby causing deposition of the silicon as a liquid layer on the inner surface of the tube from the other end to the first end, passing oxygen through said tube from the first end to the other end, thereby oxidizing the deposited silicon to silica and forming a uniform silica coating on the inner surface of the glass tube, and forming a coating of a metal oxide on said silica coating by evaporation of a metal and oxidation thereof in the same manner as with the silica, or by evaporation of a metal oxide and deposition thereof by cooling on the silica, whereby the metal oxide diffuses into the silica to dope the same.