Waveguides and quasi-waveguides based on pyrromethene 597-doped poly(methyl methacrylate) |
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Authors: | L Cerdán A Costela I García-Moreno O García and R Sastre |
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Institution: | (1) Max Born Institute, Berlin, Germany; Advanced Photonics Research Institute at the Gwangju Institute of Science and Technology, Gwangju, Republic of Korea, Germany |
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Abstract: | The characteristics of amplified spontaneous emission (ASE) from asymmetric planar waveguides and quasi-waveguides consisting
of thin films of poly(methyl methacrylate) incorporating lasing dye pyrromethene 597 deposited onto quartz and glass substrates,
respectively, are investigated. The variable stripe length and moving constant stripe methods, together with appropriate theoretical
expressions which take into account gain saturation and a simple model based on a four-level laser, allow for obtaining the
net gain coefficients as a function of pump intensity, losses, pump thresholds for the onset of ASE, effective stimulated
emission cross sections, pump saturation intensities, and saturation lengths. Net gain coefficients of up to 84±3 cm−1 at a pump intensity of 404 kW/cm2 (28 μJ/pulse) for quasi-waveguides and up to 59±6 cm−1 at a pump intensity of 360 kW/cm2 (25 μJ/pulse) for waveguides were obtained, with pump thresholds of 15.7 kW/cm2 (1.1 μJ/pulse) and 6.3 kW/cm2 (0.43 μJ/pulse), respectively. When waveguides 8 μm thick were irradiated with pulses of 200 kW/cm2 at 10 Hz repetition rate, the ASE remained at 79% of its initial value after 1000 pump pulses in the same position of the
sample. In quasi-waveguides 10 μm thick, the emission remained at 82% of the initial value under the same conditions. |
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