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Speckle characteristics of a broad-area VCSEL in the incoherent emission regime |
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| Authors: | Falko Riechert Guy Verschaffelt Georg Bastian Ingo Fischer |
| Institution: | a Light Technology Institute, Universität Karlsruhe (TH), Engesser Str. 13, D-76131 Karlsruhe, Germany b Department of Applied Physics and Photonics, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium c Faculty of Engineering, University of Applied Sciences Trier, Postfach 1826, D-54208 Trier, Germany |
| Abstract: | We present a technique to reduce the speckle contrast of a NIR broad-area VCSEL based on the spatially incoherent emission regime that can be obtained when using the proper driving conditions. We evaluate the efficiency of this technique to reduce the speckle contrast by comparing it with the speckle characteristics in multimode emission under cw operation. Depending on the illumination setup, the incoherent emission regime can lead to a strongly reduced speckle contrast down to 1.3%. This is in agreement with estimates of the expected speckle contrast reduction when three contrast reducing effects are taken into account. These low contrast values make the investigated sources attractive for several applications that suffer from speckle noise. |
| Keywords: | (250 7260) (030 6140) (110 6150) (030 1640) (030 1670) |
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