We show that, with judicious choice of opto-geometrical parameters, oscillatory waves guided by generalized left-handed slab waveguides can attain zero group velocity. Advantages compared to previous methods of slowing or stopping light are concisely discussed. © 2006 Optical Society of America.

The authors present an exact, analytic study of oscillatory modes guided by generalized asymmetric two-dimensional planar heterostructures with negative refractive index in either the core or the cladding. It is shown that, in sharp contrast to normal dielectric configurations, these waveguides always possess a frequency region where the second-order oscillatory mode may exist alone and allow for attaining zero group velocity under weak guidance conditions. In addition the mode has a field distribution that renders it excitable with an end-fire approach, making such structures attractive for applications requiring slow light. Advantages compared to previous methods of slowing or stopping light are discussed. © 2006 American Institute of Physics.

Three-dimensional full-wave electromagnetic analysis of a travelling-wave heterojunction phototransistor (HPT) is presented. Employing the finite-difference time-domain method and run on a fast, parallel processing machine the simulation herein allowed, for the first time to our knowledge, the simultaneous investigation of the optical and electrical characteristics of the travelling-wave structure. Snapshots of the field propagation inside the device provide valuable insight into its passive behaviour and conclusively demonstrate the velocity mismatch between the optical wave and the photogenerated electrical signal. Numerical results are presented for the device's output characteristic impedance, photocurrent and effective refractive indices of the optical and electrical signal that quantify the difference in the velocities of the two waves. Moreover, results obtained from the method's initial test in the simulation of an asymmetric planar optical waveguide, similar to the one integrated within the HPT's structure, compare very favourably with the theory. © 2006 IOP Publishing Ltd.

We present a detailed analytical study of surface plasmon polaritons (SPPs) in generalized asymmetric slab waveguides with a core of negative permittivity and permeability. Profiting from the duality principle, we confine ourselves to the analysis of p -polarized (TM) SPP eigenmodes, which also occur in thin metallic films. It is shown that the left-handed (LH) structures considered here support a richer variety of SPPs when compared to their metallic counterparts. Depending on the refractive index distribution, the permittivity of each medium and the thickness of the core, a total of 30 solutions to the involved characteristic equation are identified in a unified manner and classified systematically. In order to identify conclusively all SPPs, we follow an analytical methodology based directly on the solution constraints inherent in the associated transcendental equation. This treatment reveals striking features of the formed SPP eigenmodes, such as the existence of "supermodes" when no SPP is supported at one of the slab interfaces. Moreover, our study reveals the opening of gaps in the SPP dispersion diagrams, occurrence of monomodal propagation for specific choices of the material parameters, presence of SPPs with no cutoff thickness and coexistence of three eigenmodes, with double mode-degeneracy points occurring twice. The eigenmodes with negative energy flux that give rise to negative group velocity are identified via a closed-form expression for the time-averaged power flow P in the guide. For each eigenmode, we examine the variation of P with the reduced slab thickness and discuss key features of the effective index geometric dispersion diagram, most of which are unique to the generalized structures studied herein. © 2006 The American Physical Society.