Holistic characterization of complex transmittances generated by infrared sub-wavelength gratings

We present a characterization technique of wide-area sub-wavelength structures. The optical bench is based on lateral shearing interferometry, which allows an accurate complex transmittance (phase and amplitude) measurement. The experimental validation is made in the long-wavelength infrared domain; more precisely we work in the integrated 8-9 μm spectral range. Measurements of the transmitted amplitude and phase shift reveal a good agreement with respectively experimental results based on Fourier Transform infrared spectrometry, and theoretical simulations.