Electromechanical tuning of double-membrane Photonic Crystal Cavities

Photonic crystal cavities (PCCs) can provide subwavelength field confinement with very high quality factors Q, enabling new applications in the field of solid-state quantum information processing (QIP). However, the precise control of their resonant wavelength is difficult and methods for tuning it over several 10s of nm, keeping a high Q factor, are needed. In this work, a new device structure which can fulfill all these requirements was developed. It is based on the electromechanical actuation of two parallel InGaAsP membranes. Tuning is achieved by changing the effective index of the double slab waveguide displacing one of the membranes with an electrostatic field. Such a mechanism was implemented using a nanoelectromechanical structure (NEMS) based on the reverse biasing of a p-i-n junction. The main advantages of this tuning method compared to existing approaches are the potentially large tuning range, the conservation of the cavity´s quality factor and the compatibility with low-temperature operation.