Berlin 2008 – scientific programme

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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 18.29: Poster

Tuesday, February 26, 2008, 14:30–19:30, Poster A

Influence of inhomogeneous broadening on the input-output characteristics of an organic microcavity — •Susanne I. Hintschich, Hannes Gothe, Markas Sudzius, Hartmut Fröb, Vadim G. Lyssenko, and Karl Leo — Institut für angewandte Photophysik, TU Dresden, George-Bähr-Str. 1, 01069 Dresden

We investigate the input-output characteristics of a continuously tunable organic vertical cavity surface emitting laser (OVCSEL). The microcavity consists of two distributed Bragg reflectors, which enclose an active layer of the guest:host system Alq₃:DCM. The wedge-shaped geometry of this layer enables us to scan the input-output curves across the entire gain spectrum of DCM, using a single sample. Due to the high chemical stability of the material, we can reversibly monitor the behaviour over more than 2 orders of magnitude beyond the lasing threshold at the maximum of the gain spectrum. All input-output curves deviate strongly from the standard model for homogeneously broadened emitters, which uses a single spontaneous emission factor, beta. Therefore, we take into account the inhomogeneous broadening of the organic material by introducing a distribution of beta factors. Depending on the type, width and spectral position of this distribution with respect to the cavity mode, the shape of the model curve is altered. Eventually, a Gaussian distribution with suitable parameters is used to represent the inhomogeneously broadened gain spectrum of DCM. Thus, we qualitatively model the input-output behaviour of an organic microcavity laser and demonstrate the impact of inhomogeneous broadening.