Optical fiber preform having OH barrier and fabrication method thereof

This application claims priority to an application entitled "Optical Fiber Preform Having OH Barrier and Fabrication Method Thereof" filed in the Korean Industrial Property Office on Jan. 28, 1999 and assigned Serial No. 99-2696, the contents of which are hereby incorporated by reference. An optical fiber preform and a fabrication method thereof. In the present invention, an outer OH-barrier and an inner OH-barrier free of POare deposited respectively between a substrate tube and a cladding layer and between the cladding layer and a core layer during a deposition process. In addition, a refractive index increases toward the center in the core layer.