Abstract
Optical refractive index of Yb-doped laser glass was measured with white light interferometer in which output beam was dispersed using a monochromater. The measured fringe spectrum was analyzed with compensating the amplitude modulation by the absorption. The estimated complex optical refractive index is better than 2×10-4 accuracy in absolute value and better than 2×10-5 in relative value in the wavelength range between 550 nm and 1160 nm. The feature of the anomalous dispersion due to Yb doped ion was clarified, quantitatively. This analysis denoted that in the case of Yb doped system, the contribution of the doped ions becomes dominant in the higher-order dispersion of refractive index. Thermal coefficient of this laser glass was also estimated from temperature dependence of refractive index from 293 K to 373 K. It was concluded that the excellent thermal stability of this laser glass was supported from the balance between negative thermo-optical coefficient and positive thermal expansion.
