Compact Z-add-drop wavelength filters for long-range surface plasmon polaritons

We design, fabricate and investigate compact Z-add-drop (ZAD) filters for long-range surface plasmon polaritons (LR-SPPs) at telecom wavelengths. The ZAD filter for LR-SPPs consists of two ridge gratings formed by periodic gold thickness modulation at the intersections of three zigzag-crossed gold stripes embedded in polymer. We investigate influence of the grating length and crossing angle on the filter characteristics and demonstrate a 10 degrees-ZAD filter based on 80-mu m-long gratings that exhibit a 15-dB dip (centered at similar to 1.55 mu m) in transmission of the direct arm along with the corresponding similar to 13-nm-wide transmission peak in the drop arm. (C) 2005 Optical Society of America.