Germania-based core optical fibers

Germania-glass-based core silica glass cladding single-mode fibers (Delta n up to 0.143) with a minimum loss of 20 dB/km at 1.9 mu m were fabricated by the modified chemical vapor deposition (MCVD) method. The fibers exhibit strong photorefractivity with the type-IIa-induced refractive-index modulation of 2 X 10(-3). The Raman gain of 300 to 59 dB/(km (.) W) was determined at 1.07 to 1.6 mu m, respectively, in a 75 mol.% GeO2 core fiber. Only 3 m of such fibers are enough for the creation of a 10-W Raman laser at 1.12 mu m with a 13-W pump at 1.07 mu m. Raman generation in optical fiber at a wavelength of 2.2 mu m was obtained for the first time.