Highly birefringent metamaterial structure as a tunable partial polarizer.

We consider a highly anisotropic metamaterial structure, composed of parallel metal nanostripes, and show that a thin layer of the material can be used as a tunable partial polarizer. The transmittance of the structure for TE-polarized waves depends strongly on the incidence angle, while for TM-polarized waves, it stays high and essentially constant. In particular, using the structure, the degree of polarization of a partially polarized or unpolarized light can be tuned by changing the incidence angle. The TE-wave transmittance drops from, c.a., 1 to 0 when the incidence angle increases by 5 deg only, owing to the presence of an unusual higher-order odd-symmetric TM mode that we have revealed in the structure. The tuning can be made smoother by introducing another layer of a similar metal-nanostripe structure on top of the first one. The new design allows the TE-wave transmittance to decrease gradually towards 0 with the incidence angle increasing from 0 to about 30 deg. Our structures serve as an essential optical component for studies involving partially polarized light.

Optical wave retarder based on metal-nanostripe metamaterial.

Wave retarders, including quarter- and half-wave plates, are used in many optical systems for polarization conversion. They are usually realized with anisotropic crystalline materials. However, much thinner and possibly also less expensive wave plates can be made of micro- and nanostructures. We present a new way to create thin-film optical retarders based on a highly birefringent metamaterial. The wave plate is capable of low-loss, broadband operation, which we verify both numerically and experimentally. Owing to the remarkable simplicity of our design, the wave plates operating on the proposed principle can meet the requirements of large-scale production and find widespread application in optics and photonics.