Influence of unsymmetrical periodicity on extraordinary transmission through periodic arrays of subwavelength holes

Quadrate hole array is explored to study the influence of unsymmetrical periodicity on extraordinary optical transmission through periodic arrays of subwavelength holes. It is found that the transmission efficiency of light and the ratio between transmission efficiencies of horizontal and vertical polarized light can be continuously tuned by rotating the quadrate hole array. We can calculate out the transmission spectra (including the heights and locations of peaks) for any rotation angle $\theta$ with a simple theoretical model.