The ratio of the imaginary part to the real part of the complex nonlinear refractive index has been measured by transient two-wave mixing in acridine-orange-doped fluorophosphate glass, fluorescein-doped boric-acid glass, and ruby at argon-ion wavelengths. The method enables the individual signs of the components of the nonlinear index to be obtained. A simple theory based on a single homogeneously broadened absorption from the ground state agrees with measurements of the phase of the nonlinear index in acridine but not in fluorescein, where our data suggest that excited-state absorption plays an important role.
© 1989 Optical Society of America
Original Manuscript: December 30, 1988
Manuscript Accepted: June 11, 1989
Published: September 1, 1989
S. A. Boothroyd, J. Chrostowski, and M. S. O’Sullivan, "Determination of the phase of the complex nonlinear refractive index by transient two-wave mixing in saturable absorbers," Opt. Lett. 14, 946-948 (1989)