Dye-mixture laser tunable in three primary color regions with a linear variable filter

The tuning characteristics of a Coumarine 460–Disodium Fluorescein–Rhodamine 640 dye-mixture laser in the blue, green, and yellow-orange regions are reported. A linear variable filter was inserted into the laser cavity as a tuning element. The tunable range was 439–485 nm in the blue region, 509–531 nm in the green region, and 592–601 nm in the yellow-orange region. Comparison of the characteristics of the one-wavelength tuning output with those of simultaneous broadband outputs in the three color regions showed that energy transfer was an important mechanism for the oscillations, especially in the longer-wavelength region, which was farthest away from a pumping wavelength.