Abstract: A heavy metal fluoride glass composition for an optical fiber in mole percent, about: 20 to 40% InF.sub.3, 20 to 0% GaF.sub.3, 2 to 10% PbF.sub.2, 0 to 25% ZnF.sub.2, 0 to 25% CdF.sub.2,10 to 25% BaF.sub.2, 0 to 6% NaCl, 0 to 6% NaF, 0 to 7% SrF.sub.2 and 0 to 5% CaF.sub.2 ; the total of InF.sub.3 and GaF.sub.3 being about 40%; the total of BaF.sub.2, SrF.sub.2 and CaF.sub.2 being about 25%; the total of ZnF.sub.2 and CdF.sub.2 being about 25%, and the total of NaCl and NaF being about 6%; said composition being further doped with a lanthanide series heavy metal fluoride in amount up to about 1%.

Abstract: Non-oxide or heavy metal fluoride glass optical fiber with or without a cladding and coated with an outer layer of an oxide glass having a glass transition temperature of less than 400.degree. C. and a thermal expansion coefficient of less than about 19.times.10.sup.-6.C.sup.-1. Also, a method of making and providing such coatings on non-oxide or fluoride glass, and fiber optic products prepared by such methods.

Abstract: Non-oxide or heavy metal fluoride glass optical fiber with or without a cladding and coated with an outer layer of an oxide glass having a glass transition temperature of less than 400.degree. C. and a thermal expansion coefficient of less than about 19.times.10.sup.-6 .degree. C..sup.-1. Also, a method of making and providing such coatings on non-oxide or fluoride glass, and fiber optic products prepared by such methods.

Abstract: A hermetically sealed optical fiber product comprising a fluoride or other non-silica based glass optical fiber and a hermetic coating of carbon, a metal, a fluoride, a metalloid or a ceramic compound in a thickness sufficient to impart moisture resistance to the optical fiber product.

Abstract: In the manufacture of optical fibres (18) these are coated as quickly as possible with a mechanical protection, suitably in the form of a coating of silicon rubber. The coating is provided by having the fibre pass through a bath (21) of coating material after drawing. As soon as the drawing rate exceeds a certain limit the applied coating becomes uneven. In accordance with the invention this limit can be substantially increased by placing a vibrating member (23), which is in contact with the bath surface, adjacent the point (27) where the fibre (18) passes into the bath (21).