Direct thermal testing of aperiodic all-dielectric structures is presented, and its high-Q and emissivity properties are experimentally demonstrated for carbon dioxide (CO 2) gas sensing applications. Using a 7-layer dielectric stack consisting of alternating layers of silicon (Si) and silicon dioxide (SiO 2), backed by a metallic ground plane, an emissivity of 0.7 and a Q-factor of 113 are achieved at 70 ° C. Although this structure was already proposed in the literature, this is the first time direct thermal testing is reported, thereby showing narrowband emission properties of such structures when heated above room temperatures. An all-dielectric stack is thus found to be a simple, deposition-based structure that does not require any lateral mask preparation as frequency selectivity is achieved using an aperiodic arrangement of alternating dielectrics with contrasting permittivity. Superior performance over the periodically stacked structure is also demonstrated using numerical examples.

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Journal Journal of Applied Physics
Botros, J. (Joseph), Ali, M.O. (Muhammad O.), Tait, R.N. (R. Niall), Amaya, R.E. (Rony E.), & Gupta, S. (2020). Direct thermal emission testing of aperiodic dielectric stack for narrowband thermal emission at mid-IR. Journal of Applied Physics, 127(11). doi:10.1063/1.5140010