MEASUREMENT OF SATURATION INTENSITIES IN ION DOPED SOLIDS BY TRANSIENT NONLINEAR REFRACTION

The transient response of the Z-scan signal Delta T(t) was used to inv estigate the nonlinearity of ion doped solids. n(2) measurements in ru by and alexandrite were performed using an Ar+ laser. We observed that the nonlinearity response time tau decreases with the laser intensity as tau(-1)=tau(0)(-1)(1+I/I-s), where tau(0) is the excited state lif etime and I-s the transition saturation intensity. So, by measuring th e transient response at different laser intensities, we were able to d etermine not only the nonlinear complex refractive index n(2) but also tau(0) and I-s for Cr+3 in ruby and in the two alexandrite sites. (C) 1997 American Institute of Physics.