IR color separation in transmission through gratings on (110) silicon: FTIR experiment versus theory

TL;DR

This study investigates IR color separation in silicon gratings by combining FTIR measurements and rigorous simulations, revealing high-contrast filtering effects and strong agreement between theory and experiment.

Contribution

It provides a comprehensive comparison of experimental FTIR data with rigorous full-vector simulations for IR filtering in silicon gratings.

Findings

High transmission modulation ratio observed in experiments.

Quasi-periodic bright and dark spectral bands identified.

Excellent agreement between theory and experiment achieved.

Abstract

The phenomenon of filtering in zero-diffraction order is studied for transmission through 1D-periodic structures on a silicon wafer. Our study combines FTIR spectrometry in the range from 2.5 to 25 microns, and a rigorous full-vector simulation. The phenomenon exhibits itself as 'bright' and 'dark' bands in the spectra of normal transmission through grating samples, which replace each other quasi-periodically with respect to wave number, at wavelengths smaller than the grating period. The transmission modulation ratio is extremely high for two-side polished samples. Good agreement between the rigorous theory and experiment both in the range of the transmission oscillations and in the region of enhanced absorption is obtained