Abstract: A method for manufacturing an optical fiber having uniform refractive index profile, and substantially reduced macrobending loss and attenuation loss is provided comprising controlling one or more of parameters including concentration of dopant in outer region and inner region of the core region with respect to middle region of the core region of the optical fiber preform, duration of dehydration process step, concentration of chlorine gas to control refractive index of outer region and inner region of the core region for achieving a fiber having substantially uniform refractive index profile, and substantially reduced macrobending loss and attenuation loss.

Abstract: A method for producing optical fiber preform capable of producing optical fiber having low and uniform optical attenuation loss along its entire length including :he top end portion is provided. The method comprises carrying out simultaneously sintering and collapsing steps by inserting the dehydrated hollow soot porous body; with predetermined speed in hot zone of the furnace till its top end reaches the hot zone and is left for a predetermined duration thereafter the preform is uplifted for a predetermined length at a predetermined speed to avoid heat loss in the optical)reform and re-inserted in the hot zone of sintering furnace at a predetermined speed and left for predetermined duration to result in formation of the preform having collapsed capillary including at its top end.