Wankerl, Heribert and Wiesmann, Christopher and Kreiner, Laura and Butendeich, Rainer and Luce, Alexander and Sobczyk, Sandra and Stern, Maike Lorena and Lang, Elmar Wolfgang (2022) Directional emission of white light via selective amplification of photon recycling and Bayesian optimization of multi-layer thin films. SCIENTIFIC REPORTS, 12 (1): 5226. ISSN 2045-2322
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Over the last decades, light-emitting diodes (LED) have replaced common light bulbs in almost every application, from flashlights in smartphones to automotive headlights. Illuminating nightly streets requires LEDs to emit a light spectrum that is perceived as pure white by the human eye. The power associated with such a white light spectrum is not only distributed over the contributing wavelengths but also over the angles of vision. For many applications, the usable light rays are required to exit the LED in forward direction, namely under small angles to the perpendicular. In this work, we demonstrate that a specifically designed multi-layer thin film on top of a white LED increases the power of pure white light emitted in forward direction. Therefore, the deduced multi-objective optimization problem is reformulated via a real-valued physics-guided objective function that represents the hierarchical structure of our engineering problem. Variants of Bayesian optimization are employed to maximize this non-deterministic objective function based on ray tracing simulations. Eventually, the investigation of optical properties of suitable multi-layer thin films allowed to identify the mechanism behind the increased directionality of white light: angle and wavelength selective filtering causes the multi-layer thin film to play ping pong with rays of light.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | EMITTING-DIODES; GAUSSIAN-PROCESSES; DESIGN; ENHANCEMENT |
| Subjects: | 500 Science > 570 Life sciences 600 Technology > 600 Technology (Applied sciences) |
| Divisions: | Biology, Preclinical Medicine > Institut für Biophysik und physikalische Biochemie > Prof. Dr. Elmar Lang |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 07 Feb 2024 09:27 |
| Last Modified: | 07 Feb 2024 09:27 |
| URI: | https://pred.uni-regensburg.de/id/eprint/56961 |
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