Surface relief resonant Brewster filters with multiple channels

In this paper, a new type of resonant Brewster filters (RBF) withsurface relief structure for the multiple channels is firstpresented by using the rigorous coupled-wave analysis and the$S$-matrix method. By tuning the depth of homogeneous layer which isunder the surface relief structure, the multiple channels phenomenonis obtained. Long range, extremely low sidebands and multiplechannels are found when the RBF with surface relief structure isilluminated with Transverse Magnetic incident polarization lightnear the Brewster angle calculated with the effective media theoryof sub wavelength grating. Moreover, the wavelengths of RBF withsurface relief structure can be easily shifted by changing the depthof homogeneous layer while its optical properties such as lowsideband reflection and narrow band are not spoiled when the depthis changed. Furthermore, the variation of the grating thickness doesnot effectively change the resonant wavelength of RBF, but have aremarkable effect on its line width, which is very useful fordesigning such filters with different line widths at desiredwavelength.