Plasmonic Grating Based on Insulator-Metal-Insulator Structure at Telecom Wavelengths

A telecom-wavelength plasmonic grating based on an insulator-metal-insulator (IMI) structure is investigated numerically. The effective refractive index of the IMI structure is obtained. Furthermore, Bragg grating and phase-shifted Bragg grating are formed by introducing periodic thickness variation and a defect, respectively, in the width of the metal layer. The spectra can be easily tuned through changing the geometrical parameters. A high-Q factor of 890 is obtained in the plasmonic phase-shifted grating thanks to low loss and dispersion of the IMI structure. This letter develops the surface plasmon polaritons technology in metallic waveguide structures, and will lead to more optoelectronic applications.