Integrated Optical Components Utilizing Long-Range Surface Plasmon Polaritons

New optical waveguide technology for integrated optics, based on propagation of long-range surface plasmon polaritons (LR-SPPs) along metal stripes embedded in dielectric, is presented. Guiding and routing of electromagnetic radiation along nanometer-thin and micrometer-wide gold stripes embedded in polymer via excitation of LR-SPPs is investigated in the wavelength range of 1250-1650 nm.

LR-SPP guiding properties, such as the propagation loss and mode-field diameter, are investigated for different stripe widths and thicknesses. A propagation loss of ~6 dB/cm, a coupling loss of ~0.5 dB (per facet), and a bend loss of ~5 dB for a bend radius of 15 mm are evaluated for 15-nm-thick and 8-mm-wide stripes at the wavelength of 1550 nm.

LR-SPP-based 3-dB power Y-splitters, multimode interference waveguides, and directional couplers are demonstrated and investigated. At 1570 nm, coupling lengths of 1.9 and 0.8 mm are found for directional couplers with, respectively, 4- and 0-mm-separated waveguides formed by 15-nm-thick and 8-mm-wide gold stripes.

LR-SPP-based waveguides and waveguide components are modeled using the effective-refractive-index method, and good agreement with experimental results is obtained.