Dependence of the degree of conversion in difference frequency generation on the width of a dye laser emission line

A theoretical investigation is made of the influence of the width of a dye laser emission line on the efficiency of difference frequency generation (DFG) using pump radiation at different wavelengths. The line width must be reduced to obtain the maximum efficiency and the longer the DFG radiation wavelength, the narrower the line which is required. An experimental investigation is reported of the conversion of dye laser radiation of wavelength 590 nm and line width between 0.17 and 6.5 nm into difference frequency radiation; this was done using nitrogen laser pump radiation and a KDP crystal 3 cm long. The maximum degree of conversion was 3×10^–4.