Many-element lasers

Theoretical and experimental results are reported, obtained with a solid-state laser consisting of many active elements in series. A statistical treatment is developed to derive the oscillation conditions. Asymptotic expressions are given of the threshold gain per unit length holding either for a very large number of elements or for inner surface reflectivities close to 1. It turns out that lossless reflections at the inner surfaces can increase the cavityQ with respect to a one-element laser of the same active length. Preliminary experiments with five and tenelement lasers demonstrate the mode selection property of the manyelement laser and show the tendency of the system to a «quasicontinuous» emission. The possibility of obtaining some optical correction of the defects inherent in the solid material has also been demonstrated.