High Power Operation of a CW Ultraviolet Dye Laser
Within the past year, there has been increased interest in CW dye lasers operating in the near UV, due to scientific applications in this spectral region (1,2) as well as the development of higher power UV pump sources (3,4). Prior to 1988, only one laser dye, polyphenyl 1, had been shown to operate CW at wavelengths less than 400 nm (5). Polyphenyl 1 is only marginally soluble in ethylene glycol, the standard CW dye laser solvent. Furthermore, its absorption spectrum is near 300 nm, too short to be pumped effectively by the high power argon laser lines at 351 nm and 364 nm. Recently, several new UV-fluorescing dyes have been developed at Exciton, Inc. These dyes are readily soluble in ethylene glycol or another high-viscosity solvent, PPH. They are of a rigidized structure and exhibit a low Stokes shift in fluorescence. Figure 1 illustrates absorption spectra for four of the new dyes. The spectra show good overlap with the argon laser pump lines at 334–364 nm or 300–336 nm.
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