Tellurite and Fluorotellurite Glasses for Fiberoptic Raman Amplifiers: Glass Characterization, Optical Properties, Raman Gain, Preliminary Fiberization, and Fiber Characterization*

Abstract

In this study we report the physical properties and spontaneous Raman scattering spectra of nine oxide tellurite and fluorotellurite glasses from three glass systems—sodium–zinc–tellurite (TZN), tungsten–tellurite, and fluorotellurite. Raman gain and surface damage threshold at 1064 nm are also shown for a selection of these glasses, which all exhibited high gain and damage resistance. Raman gain spectra were directly measured and accurately calculated for selected TZN and fluorotellurite glasses after Fresnel, internal solid angle, and Bose–Einstein corrections. The calculated gain showed good fits to the Raman gain measurements made using a calibrated nonlinear optics apparatus. Infrared and UV‐Vis absorption spectra, characteristic temperatures obtained by differential thermal analysis, densities acquired by the Archimedes principle and refractive indices measured by spectroscopic ellipsometry are also given. The ternary systems TeO2–WO3–Bi2O3 and TeO2–Na2O–ZnF2 and the quaternary system TeO2–Na2O–ZnO–PbO show promise as Raman amplifiers as they are relatively easy to draw into optical fiber and to these authors' knowledge, this is the first time Raman gain has been presented on halide containing tellurite glasses. The oxyfluoride system studied here, TeO2–Na2O–ZnF2, exhibited a dependence on the peak Raman intensity with ZnF2 addition. Calculations of preform geometry for mono‐ and multimode guidance and stresses in similar and dissimilar (core suction) core–clad pairs are shown. Dispersion in the mid‐infrared and initial fiber drawing studies are also reported with fibers showing reasonable unclad losses.