Dual-band switchable mid-infrared emitter based on In₃SbTe₂ for gas detection application

As a highly energy-efficient and sensitive radiation source, narrowband thermal emitters provide an ideal solution for non-contact gas detection, enabling the widespread application of mid-infrared “molecular fingerprint” technology. However, most narrowband thermal emitters lack reconfigurability, limiting their adaptability in practical applications. In this study, we propose a novel dual-band switchable narrowband thermal emitter in the mid-infrared region. The emitter consists of an aperiodic Ge/SiO₂/Ge/SiO₂ (GSGS) structure and a phase change material In₃SbTe₂ (IST). When IST is in the crystalline state, the emitter achieves narrowband emission peaks at wavelengths of 3.79 μm and 6.12 μm, corresponding to the “on” state. However, when IST transitions to the amorphous state, the dual-band high emission disappears and it features angle- and polarization-independent behavior, representing the “off” state. Furthermore, we verify the physical mechanism behind the high emission through phase and amplitude calculations as well as electric field distribution analysis. Notably, the introduction of the IST provides an additional degree of freedom for tunability. Furthermore, by adjusting the thickness of the spacer layer, the emitter can be precisely tuned to match the characteristic absorption peaks of various mid-infrared gases, such as CH₄, CO₂, CO, and NO, enabling multi-gas detection in mixed gas environments. The proposed thermal emitter serves as an effective and low-cost alternative for dual-band narrowband mid-infrared light sources, contributing to the advancement of multi-gas detection strategies.