Nonlinear optical properties of Cr3+-doped laser crystals

The nonlinear optical properties in six Cr3+-doped laser crystals LiCaAlF6, LiSrGaAlF6, Gd3Ga5O12, Gd3Sc2Ga3O12, LaMgAl11O19 and Alexandrite are investigated with the help of the Z-Scan technique at lambda = 532 nm in the CW regime. The data reported here include particularly the excited state absorption cross section and the third-order nonlinear susceptibilities. It is found that the three first systems only exhibit both refractive and absorptive nonlinear effects, whereas the three others have only absorptive effects. Gd3Ga5O12 shows the best nonlinear potentialities. The excited state absorption cross section corresponding mainly to the T-4(2) -> T-4(1) transition is found to be ranging between 8.9 x 10(-22) cm(2) in LiSGaF and 3.1 x 10(-20) cm(2) in LaMgAl11O19. The calculated ratio of the third order nonlinear susceptibility to the ground state absorption coefficient is found to be largest in GGG with a value of 146 x 10(-6) esu.cm and smallest in Alexandrite (0.6 x 10(-6) esu.cm).