The high-molecular additive-polyglycol (mol.wt. 6000) being added into the solution of dye Rh-6G and water

the fluoiescencc of the dye was enhanced. In order to clarify the mechanism of the enhancement effect

the spectroscopic properties oyf de solution with and without additive v ere examined. For the dye solution without additive

the absorption spectrum of low concentration dye solution shows a main peak centred at 540nm.When the dye concentration goes up

a new absorption peak(around 500nm) appears at the short wavelength side to the previous one. The new peak may be attributed to the dimer of the dye molecules and the previous one is due to the dye monomer. Both the fluorescence intensity and the monomer absorption show paralell concentration dependance. They increase with the concentration at lower concentration range

and gradually saturate and finally decrease with dye concentration at higher concentiation range. It is concluded that the mechanism for concentration quenching of the fluorescence of the dye solution of Rh-6G and water is the dimer formation of the dye molecules.For the dye solution added with polyglycol

the dimer absorption peak decreases and nearly disappeares at higher amount of additive

and the monomer absorption peak increases

in accordance with the increase of fluorescence. The fact means that high-molecular additive effectively prevents the dye molecule from forming dimer and hence incieases the fluorescence of dye

which is related to the dye monomer. The experiments manifest that the fluoiescence enhancement can reach 300% and accordingly the laser output increases.Our results imply that it is possible to use high-molecular addtives to improve the performance of dye laser and to control various physical propeities of the dye solution.