Abstract

We have investigated several organic dyes in an effort to identify new nonlinear-optical substances because these substances are of current scientific interest owing to their possible applications in several areas. Some of the dyes investigated are 2¹,7¹-dichlorofluorescein (DCF), rhodamine 110 (R110) and pyridin 1—all doped in boric acid host. The concentration of the dyes is 10⁻³-10⁻⁴ M and the thickness of the samples is ~100 µm. Degenerate four-wave mixing experiments, using multimode Argon ion laser wavelengths, have been performed on these samples to generate phase-conjugate (PC) signals. PC reflectivities are ~10⁻⁴; the largest signals are obtained for DCF. When the pump beams are vertically polarized, the generated PC signals are also observed to be vertically polarized (vector phase conjugation). Grating growth and decay times and PC reflectivities have been measured as a function of laser power and wavelength. PC signals have been detected for angular separation between probe and pump beams as large as 90°. For samples containing DCF and R110, the grating growth and decay times are in the millisecond range. For pyridin 1, grating growth time is in seconds, and the decay time is several minutes (PC signal lasted for 1 hour).

© 1990 Optical Society of America