Optical absorption, absorption saturation and a useful figure of merit for chromium doped glasses

Chromium-doped aluminate and silicate glasses have been prepared in both inert and oxidizing atmospheres. Spectroscopic measurements indicate that some of the glasses incorporated the chromium ion in the +4 valence state. These Cr4+ doped glasses exhibit a broad spectral emission covering the communication window and the eye safe region around 1.5 mu m. Ten glass samples and two crystalline materials, were used to study the phenomenon of saturable absorption in the Cr4+ ion. A figure of merit was defined to compare the performance of different materials as saturable absorbers. The preparing conditions that lead to a glass saturable absorber with better figure of merit have been investigated. A Q-switched Cr:LiSAF laser was used for the saturable absorption measurements. Copyright (C) 1996 Elsevier Science Ltd