Broadband achromatic phase retarder based on metal-multilayer dielectric grating
Li Na1, 2, Kong Wei-Jin1, 3, †, Xia Feng1, Yun Mao-Jin1, 3
       

(color online) Designed MMDG characteristics spectrum with TE and TM waves, showing wavelength-dependent (a) phase retardation and (b) diffraction efficiency.