Investigation of the energy storage efficiency in tubular active elements of neodymium media

Experimental and theoretical investigations were made of energy processes in Q-switched lasers utilizing phosphate glasses and YAG crystals activated with Nd³⁺ ions having a pumping system in the form of a tubular active element. A theoretical analysis of the energy characteristics was made by computer simulation. It was established experimentally that in amplifiers having tubular active elements the stored excitation energy is 2–4 times higher than that in amplifiers having a conventional pumping system (for the same pumping rates). The highest efficiency achieved so far in terms of the energy stored in the active medium (~8%) was obtained. It was found that a disadvantage of tubular pumping systems is the comparatively low gain. A stored energy efficiency of ~5% was achieved in a YAG:Nd³⁺ crystal amplifier with a tubular element.