Hybrid 2D‐Material Photonics with Bound States in the Continuum

Abstract Integration of 2D materials on dielectric planar optical waveguides can make available new functionalities from the 2D materials' enhanced optoelectronic properties, such as nonlinearity, light emission, modulation, photodetection, and saturable absorption. However, the conventional integration schemes involving either the transfer of 2D materials onto prepatterned nonplanarized topology of photonic integrated circuits (PICs) or the growth and patterning of dielectric materials on 2D materials can degrade the properties of either the dielectric or the 2D material. Here, a fundamentally new and practical scheme is introduced for integrating 2D materials with PICs on a planar surface. The scheme can maintain large optical overlap with the 2D material by harnessing bound states in the continuum. This approach applies to integration of any 2D material on any single‐crystal dielectric substrate, and inherently offers strong light–matter interactions. Here, the approach is demonstrated with various hybrid photonic devices including thermo‐optic switches and filters, ultrafast photodetectors with 40‐GHz detection bandwidth, and ultrafast electro‐optic modulators with 5‐GHz modulation bandwidth. Therefore, the new platform will significantly expand the hybrid integration between 2D materials and single‐crystal dielectrics to achieve unexpected photonic functionalities.