Optical gain in Coumarin 545T-doped Tris(8-hydroxy-chinolinato)aluminium thin films

T. Rabe; P. Görrn; T. Riedl; W. Kowalsky

doi:10.1117/12.733875

16 October 2007 Optical gain in Coumarin 545T-doped Tris(8-hydroxy-chinolinato)aluminium thin films

T. Rabe, P. Görrn, T. Riedl, W. Kowalsky

Proceedings Volume 6655, Organic Light Emitting Materials and Devices XI; 66551F (2007) https://doi.org/10.1117/12.733875
Event: Photonic Devices + Applications, 2007, San Diego, California, United States

Abstract

In this paper we investigate the optical gain in organic thin film waveguides using the variable stripe length method (VSL). As active medium the guest-host system containing Tris-(8-hydroxy-chinolinato)-aluminium (Alq3) doped by 10-(2-benzothiazolyl)-2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H,5H,11H- (1)-benzopyropyrano- (6,7-8-i,j)quinolizin-11-one (C545T) is studied. The doping concentration is varied over a wide range and the gain coefficient is measured at different excitation densities to analyze the behavior of the differential gain. The F¨orster energy transfer is responsible for the occupation of the exited state of the coumarin molecules. For low doping concentrations with an inefficient host-guest energy transfer a low stimulated cross section can be observed. At optimal doping concentrations (3.7-6.4 wt%) we obtain a cross section of σ =6.8x10^-17 cm² and a high material gain of g_mat ≈500 cm^-1 at an excitation density E_ex of E_ex ≈300 μJ/cm². A further increased doping concentration (15 wt%) leads to a reduced cross section, due the onset of concentration quenching in the guest-host system. Furthermore, at high excitation densities we observe a strong saturation effect of the maximum gain which depends strongly on the doping concentration.

Citation Download Citation

T. Rabe, P. Görrn, T. Riedl, and W. Kowalsky "Optical gain in Coumarin 545T-doped Tris(8-hydroxy-chinolinato)aluminium thin films", Proc. SPIE 6655, Organic Light Emitting Materials and Devices XI, 66551F (16 October 2007); https://doi.org/10.1117/12.733875

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