Ultra-high-efficiency metamaterial polarizer

• DOI: 10.1364/optica.1.000356
• Publication Date: 2014-11-20T13:32:42Z
• Authors: Bing Shen; Peng Wang; Randy Polson; Rajesh Menon
• Keywords: 02 engineering and technology; 0210 nano-technology; 7. Clean energy

Conventional polarizers operate by rejecting undesired polarization, which limits their transmission efficiency to much less than 50% when illuminated by unpolarized light. We designed, fabricated, and characterized a multilevel metamaterial linear polarizer that rotates light with polarization perpendicular to its principal axis by 90 deg. Light with polarization parallel to its principal axis is transmitted undisturbed. Thereby, such a polarizer is able to output linearly polarized light from unpolarized input with a transmission efficiency that is substantially higher than the theoretical upper limit of 50%. A nonlinear optimization algorithm was used to design the polarizer, while multilevel focused-ion-beam lithography was used to fabricate it in silicon for the vacuum wavelength, λ0=1550 nm. We experimentally confirmed that the fabricated device enhances the transmission of the desired linear polarization by 100% compared to an unpatterned film, corresponding to a transmission efficiency of ∼74% at the design wavelength. Since our method allows for the generalized manipulation of the amplitude, phase, and polarization of light with high transmission efficiency using ultrathin elements, it should enable the efficient generation of complex vector distributions of light.