An electro-optic controllable polarization rotator based on the GaN/Al0.3Ga0.7N superlattice waveguide

III-N group material (GaN, AlN and their alloys) exhibits a promising application for infrared integrated passive photonic devices due to its unique advantages. We use wurtzite GaN/Al0.3Ga0.7N superlattices in the group material to propose an electro-optic controllable polarization rotator with the periodically left-right alternate top electrodes and a bottom electrode. By an operating voltage of 43.1 V applied on the electrodes, the rotator can realize arbitrary 90º polarization rotation. By an adjustable voltage in the ±4.9 V deviation range, the rotator can also make polarization rotation freely controlled in a full 0º~ 90º range. Due to the periodical top electrode structure of the rotator, polarization rotation is possibly controlled by choosing a different top electrode period number. As a basic function device on III-N group material, the rotator offers a simple way to control polarization in photonic integrated circuits. It can find important applications in a type of polarization-insensitive semiconductor optical amplifiers, polarization control systems, etc.