We have used the photorefractive two-beam-coupling technique to measure the nonlinear coefficient (n_2/A_eff) of several telecommunication fibers and investigated the dependence of n_2/A_eff on Er, Al, and Ge doping profiles in single-mode fibers, where n_2 is the nonlinear refractive index and A_eff is the effective area of the LP_01 mode. A semiempirical relation is derived for predicting the value of n_2/A_eff as a function of Er, Al, and Ge content in optical fibers. We have further examined the wavelength dependence of A_eff in pure and doped silica fibers between 1064 and 1552 nm and found that the A_eff value of doped fibers changes more markedly with wavelength than that of pure-silica fibers.
© 2005 Optical Society of America
(060.2300) Fiber optics and optical communications : Fiber measurements
(060.4370) Fiber optics and optical communications : Nonlinear optics, fibers
(190.4370) Nonlinear optics : Nonlinear optics, fibers
(190.5330) Nonlinear optics : Photorefractive optics
Ferdinand A. Oguama, Anthony M. Johnson, and W. A. Reed, "Measurement of the nonlinear coefficient of telecommunication fibers as a function of Er, Al, and Ge doping profiles by using the photorefractive beam-coupling technique," J. Opt. Soc. Am. B 22, 1600-1604 (2005)