Ketocyanines – a new class of lasing compounds

A new class of lasing dyes–ketocyanines–is considered. A special feature of these dyes is a large Stokes shift (3000 cm^–1) between the stimulated emission (luminescence) band and the absorption spectrum, which can be explained by a considerable increase in the strength of the hydrogen bond in the excited state. A report is given of an investigation of the lasing characteristics of ketocyanines and their mixtures with rhodamine 6G pumped with the second harmonic of a neodymium laser in a nonselective resonator. The emission range of such mixtures covers 560–640 nm, i.e., it extends over 80 nm and the individual range of emission of each of the dyes is 15–20 nm. The conversion efficiency is found to decrease with rising density of the pump radiation.