Reversed design of selective infrared emitter based on the combination of equivalent medium theory and A-star algorithm.

• The strategy based on the combination of equivalent medium theory and A-star algorithm implemented the customization of the selective emitters. • A-star algorithm was adopted for efficient and enlightening optimization of 2 or 3 parameters. • Based on the critical coupling theory, the mechanism of parameters and material changes on the performance of MDM structures were expounded. Metal-dielectric-metal (MDM) structure can selectively emit infrared wave because of the local plasma resonance; it has attracted intensive attentions in sensor, radiative cooling and many other fields. However, it remains challenging to efficiently design a customized near-ideal selective emitter. In this work, a concise design method that combined equivalent medium theory with A-star algorithm was developed for the reversed design of the MDM structure. This strategy for designing and optimizing the MDM structure, implemented the customization of the selective emitters. Meanwhile, design efficiency was improved by ∼10 times. A variety of near-ideal selective infrared emitters at 6 μm were designed based on different materials. The essence of structural parameter or material change was to adjust the radiation damping and dissipative damping of the structure to regulate the spectral radiation characteristics, such as emissivity peak and full width at half maximum (FWHM). The Q-factor of the high-performance selective emitter depends on the higher loss tangent of metals. Both the computational method and the concluded results of this work would provide enlightenment for future design of MDM structures intended for many cutting-edge applications, such as infrared sensing and radiative cooling. [ABSTRACT FROM AUTHOR]