Abstract
Three new heptamethine pyrylium dyes containing a disubstituted amino group on the meso position in their bridged chain were investigated. The solutions of the dyes in 1,2-dichloroethane (DCE) of concentration ca. 10-3 M act as laser dyes transversely pumped by a Q-switched Nd:YAG laser as a pumping source. 5.6 to 9.6% of the pump energy was converted to an intense infrared pulse with frequencies between 6580 cm-1 (1.52 µm) and 7690 cm-1 (1.30/µm). The relation between lasing efficiency and dye concentration was also studied. These dyes show a remarkable photostability upon 1.06 µm laser excitation and excellent storage stability without degassing.