Planar long-period grating filter based on long-range surface plasmon mode of buried metal stripe waveguide.

We propose a planar long-period grating filter based on coupling between the long-range surface plasmon mode and a cladding mode of a fully buried metal stripe waveguide. Using a 2.5-mm-long corrugation grating produced along the surface of an epoxy-clad aluminum stripe waveguide, we achieve a rejection band with a contrast of approximately 18 dB at the wavelength approximately 1500 nm, which can be tuned by approximately 25 nm with a temperature change of approximately 30 degrees C. The experimental results agree closely with the simulation results. The filter could find applications in surface-plasmon-based integrated-optic circuits and biosensors.