Properties of tellurite-based high numerical aperture fibers with diamagnetic core and cladding glasses

Abstract The fabrication and characterization of a tellurite based high numerical aperture magneto-optical glass fiber are presented. Different glass groups were investigated in terms of their structural, thermal, mechanical, optical and magnetic performance as a core/cladding pair and their refractive index contributions to the numerical aperture. A well matched core/cladding pair was selected: 75%TeO 2 –20%ZnO–5%Na 2 O (mol.%) for core glass, 42%TeO 2 –18%ZnO–15%K 2 O–20%Ge 2 O–5SiO 2 (mol.%) for cladding glass. The fibers have a good cross section and a numerical aperture as high as 0.9. The Verdet constant of this high numerical aperture fiber was close to that of bulk glass.