Particulate platinum (Pt) is well-known to cause damage in phosphate-based laser glass. Due to the high solubility of Pt in phosphate-based glasses, melters have been able to produce Pt- particulate free glass by converting the particulate to ionic Pt, which remains in the glass but does not cause damage. Unfortunately, the absorption of the ionic Pt that is primarily in the blue extends to approximately 600 nm in the visible. This absorption competes with the Nd⁺³ ions for pump photons. In relatively heavily Nd-doped (> 2 wt-%) elements such as disks and slabs there are sufficient Nd ions that this absorption does not cause a problem. The case for large rods is different: large clear-aperture rods require light Nd dopings in order to avoid radial gain variations. The ionic Pt can therefore seriously degrade performance both by decreasing gain and increasing heating of the host glass. This paper describes a series of calculations made that estimate the magnitude of this effect. Current production levels of ionic Pt are predicted to reduce the gain of a (phi) 90-mm, 0.55- wt-% doped rod by 10 - 15%. Results are presented for rods of diameters from 40 mm to 90 mm and for Nd dopings less than 1.0 wt-%.

Date Published: 1 June 1992
PDF: 7 pages
Proc. SPIE 1627, Solid State Lasers III, (1 June 1992); doi: 10.1117/12.60160

Published in SPIE Proceedings Vol. 1627:
Solid State Lasers III
Gregory J. Quarles, Editor(s)