Tunable Wavelength filters Based on Long-Range Surface-Plasmon-Polatiton waveguides

We design and fabricate a novel tunable wavelength filter, which utilizes long-range surface plasmon-polaritons excited along nm-thick-metal strips. A gold metal strip, with similar to cm length, 20 nm thickness, and 5,amwidth, is embedded in thick thermo-optic polymer films supported by a silicon wafer. A dielectric Bragg grating structure is placed on the metal strip, so that transmission signals at telecom wavelength are selected bythermal effect of the thereto-optic polymer. High extinction ratio of 25 dB and total insertion loss of similar to 25 dB/cm can be measured by single-mode coupling of optical fibers. We also verify that wavelength tuning of the long-range surface plasmon-polariton filters can be achieved by electric current directly applied to the metal-strip waveguides.