We report on SiO₂-Al₂O₃-La₂O₃ glasses – with and without Yb₂O₃ – suitable for nonlinear and fiber laser applications. We also present successful supercontinuum generation and fiber laser operation around 1060 nm in step-index fibers. We have optimized the glass compositions in terms of thermal and optical requirements for both a high La₂O₃ (24 mol%) and Yb₂O₃(6 mol%) concentration. The aluminum concentration was adjusted to about 21 mol% Al₂O₃ to increase the solubility of lanthanum and ytterbium in the glass beyond possible MCVD based techniques. The glasses have been characterized by dilatometrical methods to find transition temperatures from 860 to 880°C and thermal expansion coefficients between 4.1 and 7.0 × 10^-6 K^-1. Structured step index fibers with a SiO₂-Al₂O₃-La₂O₃ core and silica cladding have been realized showing a fiber loss minimum of about 500 dB/km at 1200 nm wavelength. The chromatic dispersion could be adjusted to shift the zero dispersion wavelength (ZDW) close to the pump wavelength of 1550 nm in a supercontinuum generation setup. First fiber laser experiments show an efficiency of about 41 % with a remarkably reduced photodarkening compared to MCVD based fibers.

Date Published: 11 March 2013
PDF: 12 pages
Proc. SPIE 8621, Optical Components and Materials X, 86210Q (11 March 2013); doi: 10.1117/12.2004011

Published in SPIE Proceedings Vol. 8621:
Optical Components and Materials X
Michel J. F. Digonnet; Shibin Jiang; J. Christopher Dries, Editor(s)