| 摘要 |
A method of forming a preform or blank for a high bandwidth gradient index optical filament, the preform itself and the resulting optical filament is disclosed. The preform which ultimately forms the optical filament includes a barrier layer between a tubular starting member which comprises the cladding and the core, the index of refraction of the barrier layer being equal to or less than the index of refraction of the tubular starting member; there being no step increase in the index of refraction of the barrier layer at the barrier layer-cladding interface nor of the core at the core-barrier layer interface of the optical filament. The tubular starting member is formed of a base glass and at least one dopant, the index of refraction of the tubular starting member being in excess of said base glass. The barrier layer is formed from a base glass and at least one dopant which is maintained substantially constant in the barrier layer. The core is formed of a base glass and at least one dopant which is gradually varied during the formation of the core, the core being free of B2O3. |
