We observe and theoretically analyze the plasmonic analog of the critical angle phenomenon in optical transmission through subwavelength gratings milled in an optically thick metal film. The total transmission from a denser medium to a less dense one vanishes while the total reflection holds very strong, providing the incidence angle increases past the plasmonic critical angle (PCA). The conditions and physical origins of the total internal reflection above the PCA are clarified.
© 2011 Optical Society of America
Diffraction and Gratings
Original Manuscript: July 27, 2011
Revised Manuscript: October 16, 2011
Manuscript Accepted: October 19, 2011
Published: November 25, 2011
Zhonghua Wang, Guangyuan Li, Feng Xiao, Fan Lu, Kun Li, and Anshi Xu, "Plasmonic critical angle in optical transmission through subwavelength metallic gratings," Opt. Lett. 36, 4584-4586 (2011)