Related Experiment Video
Updated: Jun 11, 2026
Fabrication of High Contrast Gratings for the Spectrum Splitting Dispersive Element in a Concentrated Photovoltaic System
Published on: July 18, 2015
Planar high-numerical-aperture low-loss focusing reflectors and lenses using subwavelength high contrast gratings
Fanglu Lu1, Forrest G Sedgwick, Vadim Karagodsky
1Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, CA 94720, USA.
Abstract:
We propose planar, high numerical aperture (NA), low loss, focusing reflectors and lenses using subwavelength high contrast gratings (HCGs). By designing the reflectance and the phase of non-periodic HCGs, both focusing reflectors and lenses can be constructed. Numerical aperture values as high as 0.81 and 0.96 are achieved for a reflector and lens with very low losses of 0.3 and 0.2 dB, respectively. The design algorithm is also shown to be readily extended to a 2D lens. Furthermore, HCG optics can simultaneously focus the reflected and transmitted waves, with important technological implications. HCG focusing optics are defined by one-step photolithography and thus can be readily integrated with many devices including VCSELs, saturable absorbers, telescopes, CCDs and solar cells.
