Enlarging the spectral accessibility of photonic zero-modes in coupled Photonic Crystal cavities through "image barrier" engineering

Photonic modes resistant to imperfections or perturbations are of paramount importance in many photonic applications. In this context, zero-modes have several advantages. Unfortunately, they are often difficult to observe. In this work, focusing on coupled photonic crystal cavities, we propose and demonstrate a technique that allows control of inter-cavity coupling without introducing concomitant frequency mismatch, thus allowing observation of zero-modes in a non-Hermitian system and testing of their robustness against asymmetries of coupling. This is done through an original "image barrier" engineering approach