We design two types of reflectors by using subwavelength high-index contrast gratings, which exhibit similar high focusing capabilities at normal incidence with a TE-polarized plane wave. One type has bars of different heights, whereas the other has bars of different depths. Both grating reflectors are designed to be approximately 22 \mu m in structural length and 10 \mu m in focal length, at an operating wavelength of 1.55 \mu m. Both achieve a full-width-half-maximum of 0.9 \mu m at the focal plane, which is fairly close to the diffraction limit. Their reflectance reach as high as 94% and 91%.
© 2014 Chinese Optics Letters
(050.2770) Diffraction and gratings : Gratings
(050.5080) Diffraction and gratings : Phase shift
(230.4040) Optical devices : Mirrors
(050.6624) Diffraction and gratings : Subwavelength structures
Diffraction and Gratings
Ting Ma, Xiaodong Yuan, Weimin Ye, Wei Xu, Shiqiao Qin, and Zhihong Zhu, "High focusing grating reflectors with TE-polarized normal incidence," Chin. Opt. Lett. 12, 020501- (2014)