Refractive index dispersion of gallium lanthanum sulfide and oxysulfide glasses

Yayama, Hiroyuki, Fujino, Shingeru, Morinaga, Kenji, Takebe, Hiromichi, Hewak, Daniel W. and Payne, David N. (1998) Refractive index dispersion of gallium lanthanum sulfide and oxysulfide glasses. Journal of Non-Crystalline Solids, 239 (1-3), 187-191. (doi:10.1016/S0022-3093(98)00737-6).

Abstract

Refractive indexes were measured for Ga₂S₃-La₂S₃ and Ga₂S₃-La₂O₃ glasses in the range of 0.48 and 1.71µm using the minimum deviation method. Data is analyzed by the Wemple equation based on the single oscillator model. These glasses have relatively large average bandgaps Eo, and electronic oscillator strengths Ed, in comparison with other chalcogenide glasses. Possible origins of these features are discussed. Introduction: Gallium lanthanum sulfide (GLS) glass is one of leading candidates for 1.3 µm optical fibre amplifiers [1], infrared lasers [2,3], acousto-optic modulators [4], and optical switching devices [5]. It possesses high quantum efficiencies of the forced electric dipole transitions, resulting from high radiative rate and low non-radiative multiphonon decay rate. These desirable properties follow from its high refractive indexes over 2.4 [6] and a low maximum phonon energy of ~ 425/cm [1]. GLS glass is of particular interest for practical devices because of its relatively low toxicity, thermal stability and ability to draw into fibre, as well as its superior optical properties. The high refractive index with a wide optically transparent range of 0.5 and 10µm [4] also results in high third-order optical nonlinearity due to the electronic origin for ultra-fast optical switching [5]. The purpose of this study is to measure accurate refractive indexes of GLS-based glasses in the UV and near-infrared region, which are useful data to characterize optical materials, and to discuss their dispersion characteristics in comparison with other chalcogenide, oxide and fluoride glasses for optic applications.

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Contributors

Author: Daniel W. Hewak

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