A hot-press molding method was used to fabricate dye-doped poly(methyl methacrylate) (PMMA) slabs. Three rhodamine dyes, Rh640 (ClO<sub>4</sub>), Rh6G(ClO<sub>4</sub>), and Rh6G (Cl), were impregnated into the PMMA matrix first by dissolving the dye and granular PMMA in a solvent mixture of chloroform and methanol and then heating the mixture <i>in vacuo</i> at 175 °C to obtain a spongy preform. The powdered preform was molded into slabs at 175 °C and at <1 mbar, to eliminate the formation of bubbles in the slabs. We annealed the slabs for several hours to improve its optical homogeneity and hence its lasing efficiency. When pumped by a 1.5-mJ nitrogen laser, we obtained peak lasing efficiencies of 8% and 7.8%, respectively, for Rh6G (ClO<sub>4</sub>) and Rh640 (ClO<sub>4</sub>) in PMMA matrices. The lasing efficiency of Rh6G (ClO<sub>4</sub>)-doped PMMA suffered a reduction rate of 0.012%/shot compared with 0.15%/shot for Rh640 (ClO<sub>4</sub>)-doped PMMA. In contrast, Rh6G (Cl) in a hot-press molded PMMA slab suffered thermal bleaching that resulted in a low lasing efficiency of <1%; this can be explained by its absorption and fluorescence characteristics.
© 1998 Optical Society of America
(140.0140) Lasers and laser optics : Lasers and laser optics
(140.2050) Lasers and laser optics : Dye lasers
(140.3580) Lasers and laser optics : Lasers, solid-state
(160.3380) Materials : Laser materials
(160.5470) Materials : Polymers
Kwong-Cheong Yee, Teck-Yong Tou, and Seik-Weng Ng, "Hot-Press Molded Poly(Methyl Methacrylate) Matrix for Solid-State Dye Lasers," Appl. Opt. 37, 6381-6385 (1998)