We report the emissive properties of a fluorene-based polymer, PF-1SOR, in planar asymmetric waveguides under optical pumping. A laser beam homogenizer setup was applied to achieve the flat-top intensity profile of the excitation light. Amplification of deep blue light via stimulated emission (SE) occurred at an energy threshold of 11 mu J cm(-2) and the amplified spontaneous emission (ASE) peak could be tuned from 411 to 423 nm. A net gain coefficient of 19.8 cm(-1) was obtained by means of the modified variable stripe length (VSL) method. The PF-1SOR thin films delivered a remarkably low loss coefficient of 1.5 cm(-1), among the lowest ever reported for a single component polymer waveguide. (C) 2009 Elsevier B. V. All rights reserved.