Inverse design of cavities for Bloch Surface Waves interfaced to integrated waveguides

The design of functional elements for Bloch Surface Waves (BSW) is challenging because of the relatively low index contrast offered by the respective platforms. Here, we design a supporting photonic nanostructure that extracts as much light as possible from a quantum emitter into a waveguide in an integrated BSW architecture. The inverse problem is solved using topology optimization. Emphasis is put on discussing the algorithm’s emerging strategies for the design to enhance the Purcell factor, the coupling efficiency, or both for different index contrasts. Fully three-dimensional simulations of an explicit device show the benefits of our devices and pave the way for integrating such unconventional photonic elements into future fully-integrated BSW devices.