Active perfect absorber based on planar anisotropic chiral metamaterials.

Active chiral plasmonics have attracted a considerable amount of research interest for their power to switch the handedness of chiral metamaterials and the potential applications in highly integrated polarization sensitive devices, stereo display fields, and so on. In this work, we propose a kind of active chiral metamaterial absorber (ACMA) composed by planar anisotropic chiral metamaterials (PACMs) and a metal layer. Our in-depth theoretical analysis indicates that the circular conversion dichroism (CCD) from PACMs plays a crucial role to achieve the active chiroptical effect. The CCD effect can enable a differentiated microcavity-interference effect between the left and right circular incident lights and results in a chiroptical effect related to the equivalent optical length between the PACMs and the metal layer. In simulations, a high-performance ACMA, which are composed by the 'Z'-shaped PACMs, is designed, and the maximum reflection CD from ACMA can reach 0.882. Meanwhile, the minimum reflection CD can reach to 0, resulting a very large adjustable range of from 0 to 0.882. The maximum modulation sensitivity, which is defined as M=∂CD/∂n and M=∂CD/∂d, can reach to about 1368.252 for d=100um and 0.06157 nm for n=4.5,respectively. In addition to the active chiroptical effect, the designed ACMA also shows excellent performance as a sensor, such as when it is being used as a highly-sensitive temperature sensor. In that case, the minimum detected precision can reach approximately 3.067 * 10 °C, if VO is used to fill the FP cavity.