Creating tunable negative refractive effect in two-dimensional photonic crystals composed of liquid crystal infiltrated air holes in Si background

In this study, we have considered a two-dimensional triangular lattice photonic crystal composed of liquid crystal infiltrated air holes in Si background. Then, we investigate the band structure, equifrequency contours, and the field intensity distribution for different values of structural parameter; using plane wave expansion and finite-difference time-domain methods. In the following, it is found that for the optimum values of geometrical parameters the structure represents a similar behavior with a system with a negative refractive index for a relatively wide frequency range. The negative refractive index causes that in a specified frequency width, the image of a light source appears perfectly on another side of the designed photonic crystal. In the end, the effect of an externally applied voltage on liquid crystals is studied. Our simulations reveal that applying the external electric filed changes the refractive index of structure and can be used for tuning the negative refractive effect.