ELSEVIEK Optics Communications 111 (1994) 263-268 1 October 1994 OPTICS COMMUNICATIONS Auger upconversion losses in Nd-doped laser glasses Stephen A. Payne, Gary D. Wilke, Larry K. Smith, William F. Kt-upke University of California. Lawrence Livermore National Laboratory, P.O. Box 5508, Livermore, CA 94550, USA Received 3 1 January 1994; revised manuscript received 20 June 1994 zyxwvutsrqponmlkjihgfedcbaZYXW Abstract We have measured the Auger upconversion constant, y. of Nd 3+ ions in phosphate, silicate, and fluoride glasses. The Auger process involves two Nd3+ ions initially in the “F,,, metastable state that interact such that one ion is promoted to a higher lying state, while the other is forced to the 41, levels of the ground state. y values ranging from 2.6 to 8.1 x 1 O- ” cm3 s-’ were measured, depending on the host medium and neodymium concentration. The product of the emission lifetime and the Auger coefficient was found to be in the range of yr= ( 1 - 2) x 10-20 cm3 for the materials investigated. This suggests that Auger upconversion is an important problem for excited state densities approaching (5-10) x 1 019cme3. 1. Introduction Solid state laser technology has continued to prog- ress such that performance can now be reliably pre- dicted. For the case of amplifier configurations, the laser performance analysis can be separated into two steps: the pumping process whereby the stored en- ergy density is created, and the extraction step where the stored energy is transferred to the laser output beam. While much work has been pursued on a vari- ety of solid state lasers, the need to understand laser media based on the Nd3+ ion has emerged as the most important objective. In spite of the common usage of gain media such as Nd : YAG, Nd : YLF and Nd-doped glasses, not all of the necessary design parameters are available at this time. While absorption and emission cross sections, storage times, and concentration de- pendent effects have come to be well characterized, other more subtle issues have not been explored as well. In this article we analyze one such issue, involv- ing the pump-induced losses associated with Auger 20 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGF 0 2P,, 7 :c Nd3+ Energy Levels upconversion of the Nd laser ions. The Auger upconversion process is illustrated in Fig. 1. Initially two neodymium ions reside in the Fig. 1. Energy levels of Nd3+ and depiction of the resonant inter- actions that lead to Auger upconversion involving two Nd ex- cited states. 0030-401 S/94/$07.00 0 1994 Elsevier Science B.V. All rights reserved SSDZOO30-4018(94)00372-2