Viscosity matching of new PbF2–InF3–GaF3 based fluoride glasses and ZBLAN for high NA optical fiber

New multicomponent PbF2–InF3–GaF3 bulk glasses have been investigated. They show lower phonon energy (540 cm−1) in comparison with 580 cm−1 for ZBLAN. Large PbF2 concentration provided glasses with high refractive index up to 1.582 and the viscosity curves revealed an excellent thermal compatibility with ZBLAYN glass. A multimode fiber with a numerical aperture of 0.51, a loss of 0.85 dB/m at 1.3 μm was fabricated using the rotational casting method.