Structural property of bismuth-doped tellurite glasses for nonlinear and Raman fiber applications

Abstract

A series of 75TeO2–(20−x)ZnO–5Na2O–xBi2O3 (mol%) glasses with x = 0, 6, 8, and 10 (TZN–Bi) were fabricated via the special melt-quench technique and characterized as candidates for fiber laser glasses. Optical absorption studies revealed that increasing the Bi2O3 content increased the cutoff wavelength and Urbach energy (ΔE) and decreased the optical band gap energy (Eopt): these trends were attributed to the structural changes occurring in these glasses. In addition to optimizing the linear transmittance and absorption, Bi2O3 increased the nonlinear refractive indexes and the Raman gain coefficients. The TZN–Bi glasses exhibited large third-order optical nonlinearities with a maximum n2 of 2.85 × 10−15 cm2/W. The peak Raman gain coefficients (29 × 10−11 cm/W) were approximately 30 times that of SiO2. These results indicate that the Bi2O3-modified glasses are promising candidates in optical applications such as Q-switching elements and Raman gain amplifiers. © 2019 Elsevier B.V. All rights reserved.