Microstructured light guides overcoming the two-dimensional concentration limit

Light guides are employed to homogenize an illumination distribution, to translate cross-sectional beam shapes, and to provide concentration. Microstructures enhance the performance of light guides based on the selective mixing of direction vector components in the two-dimensional phase space (etendue) that is perpendicular to the systemʹs optical axis. For linear concentrators we find that the microstructured light guide beats the two-dimensional concentration limit and roughly allows for a three-dimensional concentration ratio. This result is verified in simulation and experiment.