DUAL-BAND CIRCULAR POLARIZER AND ASYMMETRIC SPECTRUM FILTER USING ULTRATHIN COMPACT CHIRAL METAMATERIAL

A compact chiral metamaterial is proposed and compre- hensively investigated that can achieve circularly polarized wave emis- sion from linearly polarized incident wave (giant circular dichroism) over dual bands and near Diodelike asymmetric transmission of lin- early polarized waves. The chiral metamaterial also features exception- ally strong optical activity. For veriflcation, two proof-of-concept slab samples are designed, fabricated and measured at microwave frequen- cies. Numerical and experimental results agree well, indicating that the former dual-band circular polarizer features high conversion e-ciency around 8.1 and 9.9GHz in addition to large polarization extinction ra- tio of more than 16dB, while the latter chiral sample enables the near 90% cross-polarization transmission in one direction and almost 10% transmission in the opposite direction. The block \meta-atom" that utilized to build the ultrathin CMM slab is less than ‚0=6:73 evalu- ated at operating frequency. Good performances of the two chiral slabs with simple and compact package suggest promising applications in the circular polarizers (circulators) and transparent linear polarization transformers or spectrum fllters (isolators) that need to be interpreted with other compact devices.