Orientational relaxation in polymer and dye solutions and its consequence for the laser threshold

We compare orientational relaxation phenomena of a light-emitting polymer a nd a, spectroscopically similar, conventional laser dye in solutions of com parable viscosity. The orientational relaxation time of the laser dye is fo und to be very much smaller than that of the polymer. This result is attrib uted to the large difference in shape between the two light-emitting materi als. We demonstrate that these very different reorientation times have a ma jor influence on the operation of a gain-switched laser based on these gain media, in particular on its threshold. (C) 2001 Elsevier Science B.V. All rights reserved.