Optimal design of broadband antireflective subwavelength gratings for solar applications

We present an optimal design model with consideration of the maximum polychromatic integral transmission efficiency (PITE) for the subwavelength structure at the solar receivers surface. The integration of subwavelength structure onto the surface of the solar silica receivers leads to maximum PITE over the entire solar spectrum. With careful design optimization, for different polarization state, the optimal structure parameters are different, but the PITEs are almost the same. For TE polarization, a better average transmission efficiency can be obtained, about 99.2962%. When we consider the natural light, the structure parameters that decided by the TE polarization could be better. The optimal design method can be used to optimal the subwavelength structure to obtain maximum PITE over broad band wavelength.