Kouki ICHIHASHI^*, Yasuhiro MIZUTANI, and Tetsuo IWATA

Institute of Technology and Science, The University of Tokushima, Tokushima 770-8506, Japan

(Received March 28, 2014; Revised May 13, 2014; Accepted June 2, 2014)

To carry out precise measurements of refractive indices of nanocomposite materials, we propose a metal-diffraction-grating-based surface plasmon resonance (SPR) sensor (G-SPRS). In the G-SPRS, two SPR dips on the angular spectrum produced by two diffracted lights, the orders of which are first and negative second are utilized in a differential manner to enhance sensitivity in measurements. The principle of the G-SPRS is explained with reference to the dispersion relation of the surface plasmon induced on the metal grating. To improve precision in measurements, the fill factor of the rectangular-grooved grating is optimized. The effect of the depth of the groove on the precision is also discussed. From numerical simulations based on the rigorous coupled-wave analysis (RCWA) method, we found that the sensitivity of the proposed sensor was enhanced more than 3 times in comparison with that of the conventional sensor.

Key words: surface plasmon resonance, sensor, diffraction grating, sensitivity, RCWA

^*E-mail address: ichihashi.kouki@jp.panasonic.com