Fabrication of highly nonlinear optical fibers with tellurite glass core and phosphate glass cladding

Abstract We perform a systematic investigation of phosphate glasses containing alkaline earth, alkali and mixed-alkali oxides proposed as cladding glasses for tellurite-glass core to realize highly nonlinear optical fibers with tailored chromatic dispersion. The effects of glass composition on the optical and thermal properties of phosphate glasses are studied in this work. The phosphate glasses containing alkali oxides exhibit transmission windows in the range of 0.2–3.5 μm and refractive indices as low as 1.500 at 1544 nm. The coefficient of thermal expansion, viscosity, glass transition temperature, deformation temperature and crystallization temperature of those glasses are optimized to allow successful fiber drawing with tellurite-glass cores. We propose the 40P 2 O 5 –30ZnO–20Na 2 O–10K 2 O mol% (PZNK) mixed-alkali phosphate glass as a suitable cladding material for the 78TeO 2 –5ZnO–12Li 2 O–5Bi 2 O 3 mol% (TZLB) tellurite-glass used as a core material since they have nearly identical thermal characteristics. A successful fabrication of step-index optical fibers composed of TZLB and PZNK glasses and numerical calculations in chromatic dispersion and nonlinear coefficient are demonstrated. The large refractive index difference of 0.49 between TZLB and PZNK glasses confirms the high nonlinearity and freely-tailored chromatic dispersion profiles of these new fibers.