Dynamic optical distortions in ruby lasers

Abstract

A method to determine the variation of the average refractive index in a ruby laser caused by the direct coupling of Cr3+ ions to the average strains of the crystal lattice is presented. The method involves creation of a spatial variation of the population inversion density in the laser rod, and then measurement of the resulting dynamic divergence of the laser. The results obtained are in reasonable agreement with the values determined by other methods reported previously.

Self-Q-switching behavior of a Cr3+:LiSAF laser

“…However, its order of magnitude can be estimated by assuming its proportionality with the concentration of active ions. For the 0.05% Cr-doped ruby, it was found previously [3] that C = 6 106 and thus we can expect that C = 1.8 1 0 in the case of the 1 .5% Cr-doped LiSAF crystal that is considered in this paper. In the following, a moderate value of C is used, i.e.…”

“…Indeed, Cr3 ions slightly change their coupling to the crystal field with changes in energy state and give rise to a variation in the refractive index which is found to be proportional to the inverted population. The corresponding constant of proportionality C has been determined in the ruby case from the laser frequency chirping [1,2] or from the dynamic of the laser beam divergence [3]. Similar effects can be expected in other crystals doped with ions such as Ti3 , Cr34 , and Cr4 because of their similar electronic structure [4].…”