Vertical Cavity Surface Emitting Laser (VCSEL) for the UV Range
Ultraviolet laser-light can be implemented in a broad spectrum of applications due to its unique properties. For instance, the short wavelength of ultraviolet light can be used in optical data storage to further increase the data density. This would continue the trend in optical data storage technology of using shorter wavelengths to increase the data storage density. Currently the entertainment industry uses blue light within the Blu-ray-Technology. The next step of increasing the data density would apply ultraviolet light with even shorter wavelengths.
Furthermore, the high energetic ultraviolet laser-light can be utilized in spectroscopy and could be used in medical fields for the local and specific activation of active ingredients.
For the mentioned applications, a spectrally pure ultraviolet laser-light is required. In addition to that, an economic production and compact design of the laser-structure is desirable, in order to implement the lasers into mass devices.
The research project “Komplex-gekoppelte vertikal-emittierende Hybrid-Mikrokavitätslaser mit organischen, aktiven Halbleitermaterialien für den UV-Bereich”1, which is funded by the Deutsche Forschungsgemeinschaft(DFG) is realizing laser-structures, that face the mentioned challenges.
The idea of the new complex-coupled laser-structure is based on conventional index-coupled VCSELs (Vertical-Cavity Surface-Emitting Laser). In contrast to the index-coupled VCSELs, where the active material is located in the cavity between two Bragg-mirrors, the active material becomes also part of the mirrors in the complex-coupled VCSEL. Thus active and passive layers alternate periodically in this new type of laser structure, which is supposed to result in a lower laser threshold and a better side-mode-suppression-ratio (SMSR).
Three cooperating workgroups at the University of Kassel aim for the realization of the complex-coupled UV-emitting VCSEL. The structure of the later laser will be produced by the work group Technological Electronics in the cleanroom of the Institute of Nanostructure Technologies and Analytics. The active organic semiconductor will be synthesized by the work group Macromolecular Chemistry and Molecular Materials under the direction of Prof. Dr. Salbeck. Furthermore an optimal laser design will guaranteed by the theoretical simulations of the Computational Electronics and Photonics work group under the direction of Prof. Dr. Witzigmann.