Dual Metamaterial With Large Birefringence

Strong birefringence and a large phase delay are highly desirable for high-efficiency and compact wave plates. In order to enhance the phase delay, we combine a semiconductor metamaterial (SMM) and split-ring resonators (SRRs) into a novel dual metamaterial, which exhibits two types of resonance response, i.e., one type is mainly induced by the SMM for one polarization component of the incident wave, and the other is mainly induced by the SRRs for the other orthogonal polarization component. The unique resonance characteristics lead to large birefringence and, hence, a considerable phase delay, enabling the realization of a very compact quarter-wave plate in the middle-infrared spectrum. The concept of the dual metamaterial has the potential for developing ultracompact high-performance microoptical/nanooptical components.