Inverse designed photonic crystals for spatial filtering

Zero incidence angle spatial filters of a compact design can be very useful, among others, for intracavity spatial filtering in high-power micro-lasers. Typically, micro-lasers, especially in high-power operation regimes, emit beams of low spatial quality due to the large aspect ratio of the laser resonator. A promising proposal for compact spatial filtering is the integration of the Photonic Crystals structures into the micro-resonator of the laser. Here, we report efficient spatial filters with desired filtering properties engineered by the inverse design. Such filters can be designed not only separately for both polarizations of the incident radiation but also simultaneously for both S and P polarizations. Moreover, we fabricate the inverse-designed structure by physical vapor deposition and highlight good correspondence of the angle-wavelength transmission map to the target one.