High-Q all-dielectric thermal emitters for mid-infrared gas-sensing applications.

A simple all-dielectric thermal emitter unit cell for narrowband gas-sensing application is proposed, providing large Q-factors compared to its plasmonic counterpart. It consists of a high-index dielectric-based elliptical puck on top of a back-reflector, providing narrowband thermal emission. Using full-wave simulations, it is demonstrated that the achievable Q-factors in this structure are orders of magnitude larger than what have been shown for plasmonic cells, thanks to their low-loss electrical characteristics. Furthermore, the thermal emission properties can be engineered by manipulating the geometry of the unit cell, whereby it is shown that these unit cells can provide polarized thermal emission simultaneously in two separate frequency bands, with identical Q-factor characteristics, depending on their ellipticity parameter.