The optical properties of polimethine cyanine dyes of laser technological interest were studied with pure optical (absorption and luminescence) and photoacoustic techniques. Continuous wave or pulsed laser irradiation were used to study the properties of the less stable isomer of these compounds. Absorption spectrum, fluorescence quantum yield, Arrehnius parameters of non radiative transitions and energy content of unstable photoisomers were obtained in this way. A kinetic model for interisomer connections was proposed.