Concentric circular focusing reflector realized using high index contrast gratings

摘要

A non-periodic concentric circular high index contrast grating (CC-HCG) focusing reflector on 500 nm silicon on-insulator (SOI) platform is fabricated and experimentally demonstrated. The proposed mirror is realized with phase modulation of wave front in a high reflectivity region. The circular structure based HCG focusing reflector has a spot of high concentration at the 10.87 mm with normal incidence for radially polarization, along with the center wavelength set at 1550 nm. The FWHM spot size of the focusing beam decreases to 260 mu m, and the intensity increases to 1.26 compared with the incident beam. The focusing efficiency of about 80% is observed at 1550 nm in the experimental measurement. (C) 2017 Published by Elsevier B.V.