Berlin 2008 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 18: Poster: Towards Molecular Spintronics, Organic Thin Films, Optical Layers, Vibrational Spectroscopy, Tayloring organic interfaces

DS 18.28: Poster

Dienstag, 26. Februar 2008, 14:30–19:30, Poster A

Continuous Wavelength Tuning in a Wedge-Shaped Organic Microcavity Laser — •Bernd Schütte, Hannes Gothe, Susanne I. Hintschich, Markas Sudzius, Hartmut Fröb, Vadim G. Lyssenko, and Karl Leo — Institut für angewandte Photophysik, TU Dresden, George-Bähr-Str. 1, 01069 Dresden

Due to their broad gain spectra, lasers consisting of organic materials offer the prospect of wavelength tuning over a wide spectral range. We demonstrate a continuously tunable organic microcavity laser. Two distributed Bragg reflectors (DBRs) serve as mirrors, which are grown by reactive electron-beam evaporation. Each DBR consists of 10 alternating pairs of λ/4 layers. A guest-host composite of Alq₃ and DCM is used as the gain medium. This active layer is conveniently fabricated by thermal co-evaporation, which utilizes a rotating shadow mask in order to produce a wedge shape. Wavelength tuning is achieved by ac variation of the pump beam position on the microcavity, thus changing the resonance condition in the active layer. Its wedge-shaped profile allows to continuously select any wavelength between 595 nm and 650 nm. Thus, we scan the gain spectrum of the active medium, enabling us to optimise the laser threshold. Further scope to expand this range is provided by the high chemical stability of the organic material, which allows to pump at intensities of up to three orders of magnitude beyond the lasing threshold.