Dr. Torsten Rabe Profile

Dr. Torsten Rabe

at Technische Univ Braunschweig

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Author

Publications (9)

Proceedings Article | 27 April 2016 Paper

Combined optical gain and degradation measurements in DCM2 doped Tris-(8-hydroxyquinoline)aluminum thin-films

Marko Čehovski, Sebastian Döring, Torsten Rabe, Reinhard Caspary, Wolfgang Kowalsky

Proceedings Volume 9895, 989508 (2016) https://doi.org/10.1117/12.2227688

KEYWORDS: Luminescence, Laser applications, Thin films, Laser damage threshold, Laser optics, Waveguides, Doping, Absorption, Laser sources, Tunable lasers, Molecules

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Proceedings Article | 22 September 2015 Paper

Reduced concentration quenching in a TADF-type copper(I)-emitter

Harald Flügge, Alexander Rohr, Sebastian Döring, Charlotte Fléchon, Manuela Wallesch, Daniel Zink, Jochen Seeser, Jaime Leganés, Tatjana Sauer, Torsten Rabe, Wolfgang Kowalsky, Thomas Baumann, Daniel Volz

Proceedings Volume 9566, 95661P (2015) https://doi.org/10.1117/12.2185935

KEYWORDS: Excitons, Organic light emitting diodes, Doping, Molecules, Luminescence, Phosphorescent materials, Energy transfer, Copper, Quenching (fluorescence), Fluorescent materials

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Proceedings Article | 15 February 2012 Paper

Voltage tunable polymer laser device

Sebastian Döring, Matthias Kollosche, Torsten Rabe, Guggi Kofod, Joachim Stumpe

Proceedings Volume 8235, 82351N (2012) https://doi.org/10.1117/12.911886

KEYWORDS: Polymers, Tunable lasers, Electroactive polymers, Wavelength tuning, Actuators, Laser applications, Waveguides, Electrodes, Optical pumping, Visible radiation

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Proceedings Article | 19 May 2010 Paper

Azobenzene-based surface relief gratings for thin film distributed feedback lasers

Sebastian Döring, Torsten Rabe, Regina Rosenhauer, Olga Kulikovska, Niko Hildebrandt, Joachim Stumpe

Proceedings Volume 7722, 77221H (2010) https://doi.org/10.1117/12.854693

KEYWORDS: Thin films, Polymers, Holography, Polymer thin films, Diffraction gratings, Ultraviolet radiation, Adhesives, Waveguides, Diffraction, Modulation

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Proceedings Article | 14 November 2007 Paper

Polymer lasers: recent advances

T. Riedl, T. Rabe, P. Görrn, J. Wang, T. Weinmann, P. Hinze, F. Galbrecht, U. Scherf, W. Kowalsky

Proceedings Volume 6655, 66550V (2007) https://doi.org/10.1117/12.735896

KEYWORDS: Semiconductor lasers, Diodes, Laser damage threshold, Waveguides, Polymers, Thin films, Excitons, Absorption, Polarons, Optical pumping

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The development of organic thin film lasers has seen tremendous progress over the past few years. Only a few materials are necessary to allow for continuous wavelength tunability in the spectral region from the UV to the near IR. At the same time, the lasing thresholds of organic thin film lasers have been reduced considerably both due to improved low-loss distributed feedback (DFB) resonator structures and highly efficient gain materials based on guest-host energy transfer. Aside from the as yet open issue of electrical operation of organic lasers, which we will address briefly in this paper, there are numerous applications (e.g. in biotechnology, spectroscopy) where optically driven organic lasers may be the more cost effective and versatile solution. In this context, tunable polymer lasers pumped by compact and inexpensive InGaN laser diodes will be shown. These lasers are based on a modified poly(9,9'-dioctylfluorene) derivative (BN-PFO) containing 12% of -6,6'-(2,2'-octyloxy-1,1'-binaphthyl) spacer groups doped with a few wt% of the stilbene dye 1,4-Bis(2-(4-(N,N-di(p-tolyl)amino)phenyl)vinyl-benzene (DPAVB). With the same host polymer (BN-PFO) quasi continuous wave operation (up to 5 MHz) can be demonstrated. Highly repetitive lasers are especially desirable for many spectroscopic applications. This regime of operstion is found to be impeded by the photo-physics in doped organic systems where the accumulation of absorptive species in the gain medium leads to piled-up absorption losses and consequently to termination of the lasing process. The presence of the dopand molecules seems to strongly promote the formation and stabilization of the species which we relate to triplet excitons. Therefore, the concentration of the dopand affects the feasibility of quasi-cw operation of thin-film organic lasers. Strategies and results to achieve highly repetitive operation in low-threshold guest-host systems BN-PFO:DPAVB or BN-PFO:poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylene vinylene] (MEH-PPV) will be presented.

Proceedings Article | 16 October 2007 Paper

Loss processes in organic double-heterostructure laser diodes

Christian Gärtner, Christian Karnutsch, Jan Brückner, Nico Christ, Stephan Uebe, Uli Lemmer, Patrick Görrn, Torsten Rabe, Thomas Riedl, Wolfgang Kowalsky

Proceedings Volume 6655, 66550T (2007) https://doi.org/10.1117/12.733686

KEYWORDS: Excitons, Absorption, Polarons, Semiconductor lasers, Signal attenuation, Atmospheric particles, Laser damage threshold, Organic materials, Refractive index, Electron transport

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Proceedings Article | 16 October 2007 Paper

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

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

Proceedings Volume 6655, 66551F (2007) https://doi.org/10.1117/12.733875

KEYWORDS: Doping, Molecules, Absorption, Thin films, Energy transfer, Luminescence, Waveguides, Molecular energy transfer, Molecular lasers, Optical pumping

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Proceedings Article | 17 November 2005 Paper

Organic semiconductor distributed feedback lasers

W. Kowalsky, T. Rabe, D. Schneider, H.-H. Johannes, C. Karnutsch, M. Gerken, U. Lemmer, J. Wang, T. Weimann, P. Hinze, T. Riedl

Proceedings Volume 6008, 60080Z (2005) https://doi.org/10.1117/12.637436

KEYWORDS: Laser damage threshold, Thin films, Semiconductor lasers, Luminescence, Resonators, Organic light emitting diodes, Absorption, Organic semiconductors, Doping, Molecules

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Compared to well established liquid based dye lasers, amplifying media based on amorphous organic thin films allow the realisation of versatile, cost effective and compact lasers. Aside from that, the materials involved are organic semiconductors, which in principle allow the fabrication of future electrically driven organic laser diodes. A highly promising, low-loss resonator geometry for these lasers is the distributed feedback (DFB) structure, which is based on a periodic modulation of the refractive index in the waveguide on the nanometer scale. By variation of the grating period Λ one may tune the laser emission within the gain spectrum of the amplifying medium. We will demonstrate organic lasers spanning the entire spectral region from 360-715 nm. Tuning ranges as large as 115 nm (λ = 598-713 nm) in the red spectral region and more than 30 nm (λ = 362-394 nm) in the UV render these novel lasers highly attractive for various spectroscopic applications. As the grating period Λ is typically between 100 nm and 400 nm the DFB resonators are fabricated by e-beam lithography. These gratings may, however, be used as masters to obtain an arbitrary amount of copies by nanoimprint lithography into plastic substrates. Therefore these lasers are very attractive even for single-use applications (e.g. in medicine and biotechnology). Today, the key challenge in the field is the realisation of the first electrically driven organic laser. Key pre-requisites are highly efficient amplifying material systems which allow for low threshold operation and charge transport materials that bring about the stability to sustain the necessary current densities, several orders of magnitude higher than in OLEDs. We will demonstrate diode structures operated electrically under pulsed conditions at current densities up to 760 A/cm² with a product of the current density and the external quantum effciency (J×η_ext) of 1.27 A/cm². Mechanisms deteriorating the quantum efficieny at elevated current densities will be discussed.

Proceedings Article | 10 November 2004 Paper

Highly efficient phosphorescent guest-host-systems for hybrid inverted organic light-emitting diodes with sputtered indium-tin-oxide anodes

Michael Kroeger, Thomas Dobbertin, Daniel Schneider, Torsten Rabe, Eike Becker, Hans-Hermann Johannes, Wolfgang Kowalsky

Proceedings Volume 5519, (2004) https://doi.org/10.1117/12.558913

KEYWORDS: Organic light emitting diodes, Luminous efficiency, Electrodes, Sputter deposition, Flat panel displays, Laser induced fluorescence, Organic materials, Silicon, Doping, Thin films

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Showing 5 of 9 publications

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