Nonlinear absorption and amplification of a probe laser beam can be controlled by adjustment of the intensity-modulation frequency and the wavelength of a pump laser beam. A demonstration of this effect in Er<sup>3+</sup>-doped fluoroindate glass is presented. The results show maximum amplification of the probe beam (∼12%) when a pump laser emitting 16 mW of power is modulated at ∼30 Hz. In the limit of low modulation frequencies, or cw pumping, induced absorption of the probe beam is the dominant nonlinear process.
© 1999 Optical Society of America
G. S. Maciel, N. Rakov, Cid B. de Araújo, and Y. Messaddeq, "Control of nonlinear absorption and amplification of light in Er3+-doped fluoroindate glass," J. Opt. Soc. Am. B 16, 1995-1998 (1999)