Effect of emission wavelength on photo-stability of laser dye: experimental and theoretical study

Abstract

Photo-stability of laser dyes has been an important consideration for dye lasers. In this work, photo-stability of dye and its effect has been investigated as a function of dye laser wavelengths rather than commonly studied photo-chemical degradation pathways upon excitation with pump laser. Here, we report a significant improvement in photo-stability of the liquid dye laser at peak emission wavelength compared to edge wavelengths of the dye gain curve, which was related with an increase in rate of stimulated emission of dye at peak wavelength. Thus, high laser efficiency harmonizes to high photo-stability of the dye at peak wavelength which is useful for the applications of dye lasers. As a representative case, the photo-stability rates of pyrromethene 567 (PM567) dye at different laser emission wavelengths were studied using a 10-Hz Nd-YAG (532 nm) laser-pumped dye laser set-up under lasing and non-lasing conditions. Deterioration of dye laser efficiency on account of photo-degradation of dye molecules was theoretically simulated using a time-dependent rate equation model, which has been found to be in good agreement with the experimental observations.