Polarization-independent and reciprocity-unbroken multifunctional device with composite symmetrical structure.

ABSTRACT

A design method for a dynamically tunable multifunctional device, which is insensitive to polarization while maintaining unbroken reciprocity, is proposed. The device utilizes a multilayer composite symmetrical structure incorporating vanadium dioxide (VO2). This design enables dynamic switching among the functions of linear polarization conversion, filtering, and absorption. In the polarization conversion state, the device achieves orthogonal deflection of incident waves at any polarization angle, with a polarization conversion ratio (PCR) exceeding 95%. When switched to the filtering function, a band-stop filter with a -20 dB bandwidth of 0.56 THz is obtained. In the absorption function, the device exhibits a peak absorption efficiency of up to 99%. Furthermore, the paper discusses the potential for a dual-band device based on the proposed structure. The device maintains reciprocity in all functions and effectively handles incident waves from both positive and negative directions. This adaptability and flexibility make it suitable for various applications, including switches, sensors, and modulators.