Some characteristics of dye lasers with nitrogen laser pulse excitation

Results from experiments in which the ultraviolet pulses from a nitrogen laser are used to obtain laser action from organic dyes are described. The dyes include three in the xanthene group (rhodamine 6G, B, and sodium fluorescein) and two coumarins, 7-diethylamino-4-methylcoumarin and 7-N-dimethylamino-4, 6-dimethylcoumarin) in ethanol solvent. With these dyes, laser power is available over the entire visible range from 4200 to 6300 Å when used with a rotatabie diffraction grating. The range of tunability of one of the dyes was extended to 1000 Å by appropriate acidification. The spectral halfwidth of the light varied between 7 and 15 Å over the range of tunability. Maximum repetition rates of 100 pps were obtained. Maximum power efficiency of 25% was found for rhodamine 6G. Overall output pulse shapes were found to be in agreement with the theory of Sorokinet al. Output pulse widths varied from 1 to 7 nsec. Other dyes which we have found to lase by this method of excitation include acridone, chloro-aluminium pthalocyanine and 4-methylumbelliferone. However, these dyes will not be discussed further in the text.Partially supported by US Army Research Office, Durham, North Carolina.