An experiment has been performed to find evidence and analyze a nonlinear diverging lensing effect occurring in a flash-lamp-pumped Cr3+:LiSAF laser. The effect is assigned to a refractive-index change of the material that is proportional to the Cr3+-excited ion population, the corresponding constant of proportionality being determined from the time variation of the laser-pulse far-field divergence.

Experimental and theoretical investigation of a rapidly varying nonlinear lensing effect observed in a Cr 3+ :LiSAF laser

Modeling of the self-Q-switching behavior of lasers based on chromium doped active material

A theoretical treatment of holographic brightness for a gaussian-shaped laser pulse permits a more rigorous consideration of holographic coherence length for single-mode (TEM00q) pulse laser. Three cases are treated: (1) the ideal single frequency pulse laser oscillator; (2) the pulse laser oscillator with frequency sweep; and (3) the pulse laser oscillator with frequency sweep along with the laser amplifier with frequency shift. Some interesting theoretical and experimental holographic coherence length curves are presented for a Q-switched laser oscillator and amplifier system.

Holographic coherence length of a pulse laser

Population lensing effect in Cr:LiSAF probed by Z-scan technique

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.

Dynamic optical distortions in ruby lasers

An experiment has been performed to examine the time variation of the position and visibility of a transient interference pattern from a single‐mode, passively Q‐switched ruby laser. A blue shift in the emission frequency as a function of time is observed. The power‐dependent rate of frequency shift is 3.4 MHz/nsec·MW. This frequency shift is consistent with the results from previous experiments with a normally spiking ruby laser. A model is proposed which correlates the change in optical length of the ruby to changes in population inversion during emission. Predictions based on the model are in agreement with experimental results and with previous work.

A. Flamholz

Papers

Transient Interference Studies of Passively Q-Switched Ruby-Laser Emission