Demonstration of integrated optics elements based on long-ranging surface plasmon polaritons.
ABSTRACT An experimental investigation of long-ranging surface plasmonpolariton waves guided along thin finite width Au structures embedded in a homogeneous background dielectric is reported. The operation of key passive integrated optics elements such as straight waveguides, s-bends, y-junctions and couplers is demonstrated at a free space optical wavelength of 1550 nm. The influence of some important design parameters on the performance of these elements is presented and discussed.
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ABSTRACT: The purely bound electromagnetic modes of propagation supported by symmetric wave guide structures comprised of a thin lossy metal film of finite width embedded in an infinite homogeneous dielectric have been characterized at optical wavelengths. The modes supported are divided into four families depending on the symmetry of their fields. In addition to the four fundamental modes that exist, numerous higher order ones are supported as well. A nomenclature suitable for identifying all modes is discussed. The dispersion of the modes with film thickness and width has been assessed and the effects of varying the background permittivity on the characteristics of the modes determined. The frequency dependence of one of the modes has been investigated. The higher order modes have a cutoff width, below which they are no longer propagated and some of the modes have a cutoff thickness. One of the fundamental modes supported by the structure exhibits very interesting characteristics and is potentially quite useful. It evolves with decreasing film thickness and width towards the transverse electromagnetic TEM wave supported by the background an evolution similar to that exhibited by the s b mode in symmetric metal film slab wave guides, its losses and phase constant tending asymptotically towards those of the TEM wave. Attenuation values can be well below those of the s b mode supported by the corresponding metal film slab wave guide. Low mode power attenuation in the neighborhood of 10 to 0.1 dB/cm is achievable at optical communications wavelengths, with even lower values being possible. Carefully selecting the film's thickness and width can make this mode the only long-ranging one supported. In addition, the mode can have a field distribution that renders it excitable using an end-fire approach. The existence of this mode renders the finite-width metal film wave guide attractive for applications requiring short propagation distances and two-dimensional field confinement in the transverse plane.Physical Review B 01/2000; 611(15). · 3.77 Impact Factor
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ABSTRACT: The purely bound electromagnetic modes of propagation supported by asymmetric waveguide structures, comprised of a thin lossy metal film of finite width on a dielectric substrate and covered by a different dielectric superstrate, have been characterized at optical wavelengths. The dispersion of the modes with film thickness and width has been assessed and the effects caused by varying the difference between the superstrate and substrate dielectric constants on the characteristics of the modes have been determined. The modes are quite different from those supported by corresponding slab structures or similar finite-width symmetric waveguides. Unlike these limiting cases, the dispersion with film thickness can exhibit an unusual oscillatory character which is explained by a switching or swapping of the constituent interface modes. In addition, the four fundamental modes supported can evolve such that none has a diminishing attenuation with diminishing film thickness. This rather complex evolution of modes is unique to asymmetric finite-width structures. Under certain conditions, a long-ranging mode having a field distribution that is suitable to excitation using an end-fire technique can be supported. The long-ranging mode has a cutoff thickness below which it is no longer propagated, and its attenuation near cutoff decreases very rapidly, much more so than the attenuation related to the long-ranging mode in a comparable symmetric waveguide. Furthermore, its cutoff thickness is larger than that of the s b mode in the corresponding asymmetric slab waveguide, which implies that decreasing the film width increases the sensitivity of the mode to the asymmetry in the structure. This result is interesting and potentially useful in that the propagation characteristics of the mode can be affected by a smaller change in the dielectric constant of the substrate or superstrate compared with the s b mode guided by the corresponding slab structure.Physical Review B 01/2001; 6320. · 3.77 Impact Factor
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ABSTRACT: Surface-plasmon polaritons guided by thin, lossy metallic films bounded by dissimilar dielectric media are investigated. New solutions to the dispersion relation are found, representing waves that are leaky (radiative) in one of the dielectrics. The new waves are interpreted in terms of the coupling of a damped surface plasmon at one interface with continuum modes at the other. Their excitation by end-fire coupling techniques is suggested.Physical review. B, Condensed matter 05/1986; 33(8):5186-5201.