Tunable beam direction and transmission of light using photonic crystal waveguide

A two-dimensional (2D) square photonic crystal (PC) waveguide with the surface being modified by tubes is proposed to tune beam direction and transmission distributions. The beam direction and the transmission distribution of PC waveguide are sensitive to the surface morphology, which can be modified by filling the tubes with different organic liquids. Therefore the different beam patterns and the transmission spectrum of light from vacuum into PC waveguide can be tuned. In addition, if the tubes are filled with different liquids asymmetrically one can find an interesting off-axis directional beam phenomenon.