Optical perfectly matched layers based on the integration of photonic crystals and material loss.

Perfectly matched layer (PML) is a virtual absorption boundary condition adopted in numerical simulations, capable of absorbing light from all incident angles, which however is still lacking in practice in the optical regime. In this work, by integrating dielectric photonic crystals and material loss, we demonstrate an optical PML design with near-omnidirectional impedance matching and customized bandwidth. The absorption efficiency exceeds 90% for incident angle up to 80°. Good consistence is found between our simulations and proof-of-principle microwave experiments. Our proposal paves the road to realize optical PMLs, and could find applications in future photonic chips.