Enhancement of antireflection characteristic of resonant sinusoidal grating

Broadband antireflective characteristic is frequently achieved by sinusoidal grating in the sub-wavelength domain. Also, in the resonance domain the enhancement of antireflection for broadband spectrum and wide-angle spectrum can be obtained. For external reflection grating, the total transmittance can reach to 99.9% when the aspect ratio is larger than 1.5 for both incident polarization states. For internal reflection grating, the antireflective property in relatively narrow broadband spectrum is revealed for TE polarization. But for TM polarization, broadband antireflection at appropriate grating period and groove depth is shown. It is found that the aspect ratio of grating is a significant parameter for improving antireflection performance.