Absorptive frequency-selective transmission/reflection metamaterials with angular-insensitive and switchable octave absorption

Abstract

Absorptive frequency-selective transmission/reflection (AFST/AFSR) metamaterials (MMs) embedded with yttrium-iron-garnet are proposed, capable of achieving angular-insensitive and switchable octave absorption. The season optimization algorithm is utilized to optimize the structural parameters of the MM, thus achieving exceptional angular stability. By adjusting the discrete decreasing magnetic field applied to the MM, it can freely switch between double, triple, quadruple, and fivefold octave absorptions. Incorporating reflection layers into two symmetrical AFST MMs, which individually handle electromagnetic waves in forward and backward incidence cases, the Janus feature is realized. This accomplishment led to the achievement of the Janus AFSR MM, enabling angular-insensitive and switchable octave absorption. AFST and AFSR MMs demonstrate stable performance for TE waves under various oblique incidence angles up to 53°. The AFST/AFSR MMs showcase a novel approach to achieving angular-insensitive and switchable octave absorption, and hold significant application value in fields such as electromagnetic computing, RCS reduction, and information processing.