1450123-A is referenced by 5 patents.
1450123 Optical glass fibres POST OFFICE 13 Nov 1974 [27 Nov 1973 29 Nov 1973] 30649/73 and 55388/73 Heading C1M In a dielectric optical fibre waveguide having a core region and a cladding region (e.g. of vitreous silica) the core region comprises glass consisting of between 90 and 99À9% of silica by weight and 0À1 and 10% by weight of Si x R y where R is an anion other than oxygen. Preferably R is nitrogen and x=3, y=4. As disclosed, a mixture of argon and silicon tetrachloride is fed to a mixing chamber 1 via pipe 5 and nitrogen via pipe 4, the streams being combined and adequately mixed by passage through silica wool 7 to a pipe 8 and thence to the induction coupled plasma discharge 11. Pipes 9 and 10 are concentric with pipe 8, pipe 9 initially carrying argon, then a mixture of argon and oxygen and pipe 10 oxygen, the exterior of pipe 10 being cooled by a water jacket.; The plasma torch is powered by radio frequency coupled to the plasma by coil 12. The resultant boule is condensed on to a rotating target. The boule is then heated to over 800 C. in an oxygen containing atmosphere to form a SiO 2 cladding, withdrawing into fibre form before or after heating. Alternative gas mixtures for making the doped silica are SiH 4 or SiCl 4 or Si 2 OCl 6 mixed with (1) NO+N 2 +NH 3 , (2) N 2 O+NH 3 + N 2 or (3) NH 3 +N 2 or Si(NR 1 R 2 ) x (OR 3 ) 4-x +N 2 +NH 3 (wherein R 1 , R 2 and R 3 are organic radicals).