Differential method for modeling dielectric-loaded surface plasmon polariton waveguides

Active metal strip hybrid plasmonic waveguide with low critical material gain

An active metal strip hybrid plasmonic waveguide (MSHPW) using gain materials as loss compensation is proposed with an extremely simple fabrication procedure. Gain materials are introduced either in the low-index layer or in the high-index layer of MSHPW. The effects of waveguide dimensions and material gain coefficients on loss compensation are analyzed at the communication wavelength. For one configuration presented here, a critical material gain as low as 3.8cm(-1) is sufficient for fully compensation of the loss when using a high-index gain material. The active MSHPW with low critical material gain opens up opportunities for practical plasmonic devices in active applications such as amplifiers, sources, and modulators.

Excitation of a one-dimensional evanescent wave by conical edge diffraction of surface plasmon

The experimental observation of a one-dimensional evanescent wave supported by a 90◦ metal edge is reported. Through a measurement of in-plane momenta, we clearly demonstrate the dimensional character of this surface wave and show that it is non-radiative in the superstrate. Excitation conditions, lateral extension and polarization properties of this wave are discussed. Finally, we explore the effect of the surrounding dielectric medium and demonstrate that a single edge can sustain distinct excitations.

Numerical investigation of mode characteristics of nanoscale surface plasmon-polaritons using a pseudospectral scheme

This study uses a full vector pseudospectral scheme in the frequency domain to investigate the mode characteristics of surface plasmon-polariton (SPP) waveguides. The wave equations solved in this study are based on the transverse magnetic field components, and thus the spurious modes are removed due to the constraint of divergence-free magnetic vector. The waveguide dimension dependences on the mode confinement and propagation length of the dielectric-loaded surface plasmon-polariton waveguide (DLSPPW) are extensively studied and characterized. The numerical results of the DLSPPW show that the proposed scheme is highly efficient and yields accurate complex effective indices while requiring much less memory than the commonly used finite element method. This study also analyzes the propagation characteristics and figures of merit of an inverted metal slot waveguide (IMSW) in detail. The IMSW achieves a propagation loss an order of magnitude lower than nanoparticle chains with comparable degrees of lateral confinement.

Refractive micro-optical elements for surface plasmons: from classical to gradient index optics

Controlling the propagation of surface plasmons along a metal-dielectric interface is a key feature for the development of surface plasmon based circuits. We have designed various two-dimensional refractive dielectric optical elements for surface plasmons (SP) and characterized their capacity to route SP, using near- or far-field techniques. We first present basic devices analogous to usual optical components and the associated challenges for SP optics. We then use a metamaterial approach to locally vary the refractive index and fabricate gradient index structures for SP circuitry.

Gain-assisted propagation in a plasmonic waveguide at telecom wavelength

The spatial confinement of surface plasmon polaritons is a promising route for realizing optical on-board interconnects. However, mode losses increase with the confinement factor. To overcome this road block, we investigate propagation assisted by stimulated emission in a polymer strip-loaded plasmonic waveguide doped with nanocrystals. We achieve 27% increase of the propagation length at telecom wavelength corresponding to a 160 cm(-1) optical gain coefficient. Such a configuration is a step toward integrated plasmonic amplifiers.