High-resolution monitoring of wavelength shifts utilizing strong spatial dispersion of guided modes

A prism-coupled metal-dielectric-metal waveguide structure is presented to detect slight variations in wavelength. Strong spatial dispersion ability is exhibited at the guided-mode resonance, which leads to a rapid changing of the reflected beam shift with respect to the light wavelength. It is demonstrated to be an effective way to enlarge the lateral shift of the reflected beam by increasing the guiding layer thickness, which helps to improve the sensitivity of the wavelength-shift monitoring. A wavelength resolution as high as 0.027 pm is achieved in the experiment. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4740258]