Large-Area Dual-Band Hybrid Metagrating Thermal Emitter for Gas Detection

Metasurface thermal emitters offer an energy-efficient, compact and sensitive option for non-contact gas detection radiation sources, which make "molecular fingerprints" accessible to a wide range of applications from medical diagnostics to environmental monitoring. However, the majority of narrow band emitters suffer from designing for a single target gas, hindering the miniaturization of multi-gas detection system. In this work, a one-dimensional hybrid metagrating emitter is adopted to realize dual-band polarization-distinguishable emission spectra by the excitation of metal-assisted guided mode resonance and surface plasmon polaritons and easily match the two different absorption peaks of gases CH ₄ , CO ₂ , CO, NO, and NH ₃ ) in the 3-6 μm range to reduce the effect of the gas mixture on measurements. Compared to conventional metal-dielectric-metal structures, a calculated higher Q-factor and more significant change of the directional radiation intensity can be achieved due to less material loss with single metal layer, enabling highly sensitive gas detection. In addition, the proposed metagratings are fabricated on a large scale by maskless lithography and are measured experimentally to verify the validity of our design. This work provides a promising method to the miniaturization and integration of multi-gas channel detection and promotes a more accurate and sensitive sensing strategy.