We report broadband reflectance in the long-wavelength infrared (LWIR, 8-12 μm) utilizing suspended-Si, high-index-contrast subwavelength gratings (HCGs). Iterative design optimization using finite element analysis software has been performed accounting for silicon’s wavelength-dependent index of refraction and extinction coefficient. Grating arrays were fabricated using commercial silicon-on-insulator (SOI) substrates, photolithography and reactive ion etching; subsequent selective wet etching of SiO₂ was used to provide suspended Si/air gratings. Fourier transform infrared (FTIR) spectroscopy demonstrates broadband, polarization–dependent reflectance between 8.5 and 12 μm, which agrees with the simulated response.

Date Published: 15 March 2013
PDF: 7 pages
Proc. SPIE 8633, High Contrast Metastructures II, 863310 (15 March 2013); doi: 10.1117/12.2014532

Published in SPIE Proceedings Vol. 8633:
High Contrast Metastructures II
Connie J. Chang-Hasnain; Fumio Koyama; Alan Eli Willner; Weimin Zhou, Editor(s)