Amplified spontaneous emission and optical gain measurements from pyrromethene 567 - doped polymer waveguides and quasi-waveguides

Amplified spontaneous emission from planar waveguides and quasi-waveguides based on Pyrromethene 567-doped poly( methyl methacrylate) thin films deposited onto quartz and glass substrates is investigated. Films with different thickness were prepared and pumped optically at 532 nm with pulses of up to 8 MW/cm(2). Pump thresholds for the onset of ASE emission, optical gains and losses were assessed. Net gain coefficients were estimated by fitting the data provided by variable stripe length measurements with a theoretical expression which takes into account saturation. In this way, net gain coefficients of up to 56 +/- 9 cm(-1) at a pump intensity of 5.3 MW/cm(2) for quasi-waveguides and up to 20.6 +/- 2.7 cm(-1) at a pump intensity of 3.4 MW/cm(2) for waveguides, were obtained. Loss coefficients in the waveguides were estimated to be 3.8 +/- 0.4 cm(-1) and 6.1 +/- 1.3 cm(-1) for 15 mu m and 5 mu m thick films, respectively. The results obtained seem to indicate a stronger self-mode-restriction capability in the quasi-waveguides than in conventional total internal-reflection waveguides. (C) 2008 Optical Society of America.