T. Ohtsuki et al., COOPERATIVE UP-CONVERSION EFFECTS ON THE PERFORMANCE OF ER3-DOPED PHOSPHATE-GLASS WAVE-GUIDE AMPLIFIERS(), Journal of the Optical Society of America. B, Optical physics, 14(7), 1997, pp. 1838-1845
The cooperative upconversion processes of erbium ions in silver film i
on-exchanged waveguides in a phosphate glass were studied from the pum
p intensity dependence of luminescence decay curves. Cooperative upcon
version coefficients of the I-4(13/2) level, 7.7 +/- 0.7 x 10(-19) and
9.3 +/- 0.7 x 10(-19) cm(3)/s, were obtained for an Er3+ concentratio
n of 1 x 10(20) Cm-3 in bulk and waveguide samples, respectively. Thes
e values are 1 order of magnitude smaller than the ones reported for s
ilica glass. The increase in the cooperative upconversion coefficient
with the increase in Er3+ concentration was found to be small. The eff
ects of cooperative upconversion on the gain performance were analyzed
for different Er3+ concentrations by a theoretical model based on exp
erimentally measured gain with a 1.48-mu m pump wavelength. Given the
small cooperative upconversion coefficients in this glass, Er3+ concen
trations potentially as high as 3.7 x 10(20) cm(-3) were shown to be f
easible. Such high concentrations would result in a 12-dB gain at 150-
mW pump power with a 4-cm-long waveguide. (C) 1997 Optical Society of
America.