Broadband polarization independent light absorption using ultrathin plasmonic super absorbers

K. Aydin, V. E. Ferry, R. M. Briggs, and H. A. Atwater California Institute of Technology

Achievement: We have demonstrated an ultrathin (260 nm) plasmonic super absorber consisting of a metal-insulator-metal stack with a nanostructured top silver "lm composed of crossed trapezoidal arrays. The super absorber yields broadband and polarization-independent resonant light absorption over the entire visible spectrum with an average measured absorption of 0.71 and simulated absorption of 0.85. Our metallo-dielectric absorber employs a structure of subwavelength thickness whose constituent materials are lossless dielectrics and highly re$ective metals. Signi!cance: Metallic nanostructures with broadband plasmonic resonances may enhance the absorption in solar cells over a broad wavelength range, and enable broadband absorption and photocarrier generation in active semiconductors. Nanostructured absorbers could also play a significant role in thermophotovoltaics and thermoelectrics.

Ag SiO2

Ag

Experiment Theory

Extinction

500 nm 100 nm

Aydin et al., Nature Communications, 2, 517 (2011)

October 2011 Research Highlight