Corrugated neat thin-film conjugated polymer distributed-feedback lasers |
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Authors: | W Holzer A Penzkofer T Pertsch N Danz A Bräuer EB Kley H Tillmann C Bader H-H Hörhold |
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Institution: | Institut II – Experimentelle und Angewandte Physik, Universit?t Regensburg, Universit?tsstrasse 31, 93053 Regensburg, Germany, DE Fraunhofer Institut für Angewandte Optik und Feinmechanik Jena, Schillerstrasse 1, 07743 Jena, Germany, DE Institut für Angewandte Physik, Friedrich-Schiller Universit?t Jena, Max-Wien Platz 1, 07743 Jena, Germany, DE Institut für Organische Chemie und Makromolekulare Chemie der Universit?t Jena, Humboldtstrasse 10, 07743 Jena, Germany, DE
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Abstract: | Wave-guided thin-film distributed-feedback (DFB) polymer lasers are fabricated by spin coating a PPV-derived semiconducting
polymer, thianthrene-DOO-PPV, onto oxidised silicon wafers with corrugated second-order periodic gratings. The gratings are
written by reactive ion beam etching. Laser action is achieved by transverse pumping with picosecond laser pulses (wavelength
347.15 nm, duration 35 ps). The DFB-laser surface emission and edge emission are analysed. Outside the grating region the
polymer film is used for comparative wave-guided travelling wave laser (amplified spontaneous emission (ASE)) studies. The
pump pulse threshold energy density for wave-guided DFB-laser action (4–9 μJ cm-2) is found to be approximately a factor of two lower than the threshold for wave-guided travelling wave laser action. The
spectral width of the DFB laser (down to ΔλDFB≈0.07 nm) is considerably narrower than that of the travelling wave laser (ΔλTWL≈14 nm). The DFB-laser emission is highly linearly polarised transverse to the grating axis (TE mode). Only at high pump pulse
energy densities does an additional weak TM mode build up. The surface-emitted DFB-laser radiation has a low divergence along
the grating direction. For both the DFB lasers and the travelling wave lasers, gain saturation occurs at high excitation energy
densities.
Received: 7 January 2002 / Revised version: 15 February 2002 / Published online: 14 March 2002 |
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Keywords: | PACS: 42 70 Jk 42 55 -f 78 55 Kz |
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