Angle Tolerant Mid-Infrared Notch Filters using Two-Dimensional Amorphous Germanium High Index Contrast Sub-Wavelength Gratings

We experimentally demonstrated polarization independent, angle tolerant mid-infrared notch filters using amorphous-Germanium 2D high contrast gratings. Centered at 7.42 μm wavelength, the filter exhibits wide field-of-view notch filtering characteristics across 0 to 30° incidence angles.