NONLINEAR ABSORPTION AND LASER-INDUCED GRATINGS IN GLASSES DOPED WITH ACRIDINE-ORANGE AND METHYL-ORANGE

The nonlinear optical properties of two organic dyes, methyl orange and acridine orange, embedded in a composite glass were measured by means of nanosecond pump- and probe beam spectroscopy and by the technique of cw laserinduced gratings (LIG). In the pump- and probe beam experiment we observe effects like bleaching and induced absorption, dependent on the dye studied, the excitation power and the number of excitation pulses. The relaxation times after excitation back to the original state lies in the range of one minute (methyl orange) or of several hours (acridine orange) for the lower energetic side of the absorption edge. In the LIG measurements with a cw-Ar+ laser we detect self-diffraction for both materials. In the case of methyl orange we have a phase grating, in the case of acridine orange the grating is due to a combination of absorptive and dispersive changes.