High‐performance integrated mid‐infrared filter arrays

A static filter array is developed based on Fabry–Perot cavities operating in the mid-infrared range from 2 to 4.5 µm, matching absorption region of several gases relevant for air quality monitoring. The filters include two distributed Bragg reflectors and a high-index tuning element with varying thickness between. display high peak transmittance ( > 80 % $>80\%$ ) controllable width. robustness, ease fabrication possibility tune optical response specific application make integrated arrays suitable compact sensing systems.