OPTICAL FIBER BLANK WITH OH BARRIER (VERSIONS) AND METHOD OF ITS MANUFACTURE Russian patent published in 2002 - IPC

FIELD: manufacture of optical fiber blanks. SUBSTANCE: optical fiber blank includes bearing tube, envelope layer and core layer. Blank includes additionally first barrier layer between supporting tube and envelope layer deposited from material having low OH diffusion coefficient where first layer is essentially layer preventing diffusion of OH containing in bearing tube into envelope layer. Besides, optical fiber blank includes second barrier layer formed between envelope layer and core layer by settling of material having low OH diffusion coefficient, thus preventing diffusion of OH which diffuses into envelope layer from bearing tube and then to core layer. Inner and outer barriers of OH not containing P₂O₅ are settled between bearing tube and envelope layer, as well as between envelope layer and core layer during deposition process, thus excluding diffusion of OH from bearing tube to core layer during deposition, compression and jointing processes. EFFECT: reduced losses at simultaneous reduction ratio of envelope and core diameters. 14 cl, 6 dwg