Theory of Laser Giant Pulsing by a Saturable Absorber

TLDR

Recent experiments have demonstrated laser giant pulsing by inserting a saturable absorber into the cavity as a fast switch. This study calculates giant pulse rise/fall times and peak power as functions of the absorber‑to‑laser cross‑section ratio σ, normalized inversion nai, and mirror transmission Tr, and derives a minimum σ criterion for giant pulsing. The authors develop a theoretical model that computes pulse parameters from σ, nai, and Tr, derives the minimum σ condition, and validates the results with numerical examples and a discussion of the theory’s applicability. The analysis shows an optimal mirror transmission for maximum peak power, predicts that peak output increases with σ and approaches the Wagner–Lengyel limit as σ→∞, and confirms these predictions through numerical examples.

Abstract

Several experimental demonstrations of laser giant pulsing using a saturable absorber inside the laser cavity as a fast switch have recently been reported. In the present work giant pulse parameters such as pulse rise and fall times and peak power are calculated as a function of σ, the ratio of absorber to laser ion cross sections; nai, the normalized inversion prior to switching; and the laser mirror transmission Tr. It is shown that there is an optimum Tr for the extraction of maximum peak power. A criterion for the minimum σ for giant pulsing to occur is derived. The largest output occurs when σ → ∞ in which case the theory approaches that of Wagner and Lengyel. Some numerical examples are presented as well as a discussion of the range of validity of the theory.