We propose a refractive index sensor based on the interference of two surface-plasmon waves on both surfaces of a gold film with a two-slit structure. The phase of the interference was solved, and the dispersion relation of the real part of Au dielectric function was considered. The sensor was performed with NaCl−H2O solutions of different concentrations and exhibited a linear response and a high sensitivity of 4547 nm/RIU (refractive index unit) to the refractive index change.
© 2009 Optical Society of America
Original Manuscript: September 12, 2008
Revised Manuscript: December 12, 2008
Manuscript Accepted: December 12, 2008
Published: January 30, 2009
Xiaofei Wu, Jiasen Zhang, Jianjun Chen, Chenglong Zhao, and Qihuang Gong, "Refractive index sensor based on surface-plasmon interference," Opt. Lett. 34, 392-394 (2009)