Beam steering with graded index photonic crystal lens and liquid crystal

In this numerical study, a new compact and tunable beam-steering device composed of graded index photonic crystal lens and liquid crystal material has been presented and demonstrated. The beam-steering device can work in two modes: First, incident single wavelength beam steers by tuning the refractive index of the liquid crystal material. Second, by fixing the refractive index of the liquid crystal material, incident multi-wavelength beam steers with different off-axis angles for each wavelength. The numerical simulations with finite-difference time-domain method reveal that wide-angle, ±28.4°, beam steering can be achieved when the length of the liquid crystal layer equals 5.17 μm. Moreover, the wavelengths over λ = 1.518-1.553 μm or λ = 1.487-1.518 μm can be steered to different angles. A special characteristic of the presented structure gives an opportunity to be used as an efficient element in a high integrated optical device for miniaturisation and tuning purposes.