The distributed gain of single- and dual-wavelength-pumped thulium-doped fiber amplifiers is modeled. The excellent agreement between the model and coherent optical frequency domain reflectometry measurements enables us to estimate intrinsic loss, branching ratios of fluorescence originating from the H<sub>4</sub><sup>3</sup> level, and cross sections of upconversion pumping at 1050 and 1410 nm for the Tm<sup>3+</sup> ions in the fiber. With the branching ratios obtained it is possible to describe induced signal absorption when pumping at 800 nm.
© 2004 Optical Society of America
Claudio Floridia, M. T. Carvalho, S. R. Lüthi, and A. S. L. Gomes, "Modeling the distributed gain of single- (1050 or 1410 nm) and dual-wavelength- (800 + 1050 nm or 800 + 1410 nm) pumped thulium-doped fiber amplifiers," Opt. Lett. 29, 1983-1985 (2004)