Actively Tunable Angle-Independent Mid-Infrared Optical Filters Using GST Fabry-Perot Resonators

Germanium antimony telluride (GST) properties and experimental results of mid-infrared optical filter are demonstrated. Incorporating sub-wavelength gratings of GST-Ag, Fabry-Perot resonators produce transmission peak are observed. Active tuning by, thermal excitation, of GST shifts refractive index from 3.48-4.61 while maintaining angular independence up to 60°.