Lateral Leakage in Silicon Photonics: Theory, Applications, and Future Directions

This paper presents an overview of lateral leakage in silicon photonics due to polarization coupling between the guided mode of a ridge waveguide and unguided slab mode in the etched cladding. We explain the physical origins and provide insight into how this effect can be suppressed or harnessed. We show how lateral leakage can manifest as new resonant behaviour and explore this effect in the context of bound states in the continuum. We review a number of applications for devices based on lateral leakage and present outlook for a new generation of polarization manipulators, antennas and filters.