A dendrimer dye laser

Has been demonstrated. A conventional dye laser uses fluorescing dye molecules as the active medium. When excited with an external laser, the molecules emit a range of wavelengths that are then tuned by the dye-laser cavity. In most dye lasers, the dye concentration cannot go above a millimole/liter without quenching the fluorescence. Now, scientists at the Communications Research Laboratory in Japan and PRESTO Japan Science and Technology Corp have achieved lasing with a dye concentration of 9 mmol/l by encapsulating the dye molecules at the heart of hyperstructured, tree-shaped polymers called dendrimers. As the dye concentration increased within the new dendritic high-gain medium, the laser output also increased while the lasing threshold decreased. Furthermore, the resultant spectral linewidth was only 0.1 nm. The researchers are now working to incorporate their dendrimers into solid-state waveguides, optical fibers, and photonic crystals. ( S. Yokoyama , A. Otomo , S. Mashiko , Appl. Phys. Lett. 80, 7, 2002.)