Digital resonance tuning of high-Q∕Vm silicon photonic crystal nanocavities by atomic layer deposition

We propose and demonstrate the digital resonance tuning of high-Q∕Vm silicon photonic crystal nanocavities using a self-limiting atomic layer deposition technique. Control of resonances in discrete steps of 122±18pm/hafnium oxide atomic layer is achieved through this postfabrication process, nearly linear over a full 17nm tuning range. The cavity Q is maintained in this perturbative process, and can reach up to its initial values of 49 000 or more. Our results are highly controllable, applicable to many material systems, and particularly critical to matching resonances and transitions involving mesoscopic optical cavities.