Abstract

An all-optical NAND logic gate derived from the negative nonlinear absorption effect was demonstrated in erbium-lutetium aluminum garnet crystals using “1532 nm laser diode. With a decreasing incident modulation degree, a reversed-phase waveform was obtained in the transmitted laser at modulation degrees smaller than 90% for sample lengths greater than 1.0 mm. The reversed-phase transmitted waveforms were observed at modulation frequencies from 100 kHz to 1 GHz. The negative nonlinear absorption effect can be explained by Considering an enhanced absorption model for a four-level system of the Er³⁺ ion.

© 1999 Optical Society of America