We constructed a metallic grating on a deep-subwavelength scale and tested its plasmonic features in visible frequencies. The deep-subwavelength metallic grating effectively acts as an anisotropic homogeneous uniaxial form-birefringent metal, exhibiting different optical responses for polarizations along different optical axes. Therefore, this form-birefringent metal supports anisotropic surface plasmon polaritons that are characterized by directly imaging the generated plasmonic index ellipsoids in reciprocal space. The observed plasmonic index ellipsoids also show a rainbow effect, where different colors are dispersively distributed in reciprocal space.
© 2011 Optical Society of America
Original Manuscript: June 29, 2011
Manuscript Accepted: July 21, 2011
Published: September 9, 2011
Liang Feng, Zhaowei Liu, and Yeshaiahu Fainman, "Direct observation of plasmonic index ellipsoids on a deep-subwavelength metallic grating," Appl. Opt. 50, G1-G6 (2011)