Spectroscopic Studies of New Blue Laser Dyes in Tetrahydrofuran Solution and in Composite Glass

We have investigated the linear absorption, emission wavelength-dependent excitation, fluorescence polarization excitation, and lasing properties of new UV-blue dyes. The dyes are didecyl para-polyphenyl heptamer (DDPPH), didecyloxy para-polyphenyl heptamer (DDOPPH), and bisbenzothiazole 3,4- didecyloxy thiophene (BBTDOT). We studied the effect of dye concentration on absorption and emission and the origin of the peaks in tetrahydrofuran solution and in a composite glass. We show that, in a composite glass, it is possible to impregnate the dye with density of several orders without aggregation effects. The two heptamer dyes were found to be very photostable. All three dyes are promising candidates as laser dyes in the UV. Under excitation with a frequency-doubled dye laser (300 nm), the DDPPH lased at 377 nm. The DDOPPH lased at 425 nm and the BBTDOT lased at ∼450 nm when excited by the third harmonic of a Nd:YAG laser (355 nm). The output from the second heptamer in tetrahydrofuran was photostable (less than 10% decrease) for more than 900,000 pulses and with a slope efficiency of approximately 20%.