Nanostructured Optical Coatings for Spatial Filtering and Polarization Control

In micro-lasers, especially in high power emission regimes, the spatial quality of laser light beam deteriorates. Typically, a confocal arrangement of lenses with a diaphragm in the focal plane is used for intracavity spatial filtering. Such conventional filtering requires access to the far-field domain. In microlasers, however, conventional filtering is impossible due to the lack of space in micro-resonators to access the far-field. Therefore, a novel concept for more compact and efficient spatial filtering is necessary.