Optimization of gain-assisted waveguiding in metal–dielectric nanowires

Abstract

We theoretically demonstrate that, for a given diameter of the core-pumped metal-dielectric nanowire, there is an optimum thickness of the metallic cladding that provides the maximum propagation length of the lowest-order surface plasmon polariton (SPP) modes. If the nanowire is fabricated with the optimum cladding thickness, the lowest pumping power is required to fully compensate for the SPP propagation losses. We also show that a strong confinement of SPPs within the nanowire can be achieved, but at the expense of either high optical gains or large nanowire diameters. For example, a gain of 565 cm(-1) would suffice to make up for the decay of SPPs in a 250-nm-thick silver-GaAs nanowire; the confinement of optical power within such nanowires exceeds 90%, which makes them ideal interconnects for nanophotonic circuitry.

Optimizing the design of planar heterostructures for plasmonic waveguiding

“…We assume that the difference in the pump and signal wavelengths is much larger than their bandwidths, and we neglect the interference between them. We model gain by assuming a negative imaginary part for the dielectric permittivity [14,26], i.e.,…”

“…Thus, for efficient operation of the waveguide, it is essential to enhance the propagation length of the SPPs by providing optical gain to the dielectric. To achieve gain, one may optically pump the doped dielectric layer in the x direction, in cases where the metal is sufficiently thin [26]. In Ref.…”

“…In our previous work, we optimized the design of cylindrical composite nanowires to minimize the gain requirement [14,26]. In this paper, we optimize the design of planar composite plasmonic waveguides to ensure efficient waveguiding of surface plasmon polaritons (SPPs).…”

Guided Plasmon Modes of a Graphene-Coated Kerr Slab

“…The surface conductivity of graphene (σ g ) can be effectively modulated via tuning its chemical potential (μ) through chemical doping, or electrostatic or magnetostatic gating [1]. For Im σ g > 0, graphene behaves as a very thin metal layer capable of supporting transverse magnetic (TM) surface plasmons (SPs) [7][8][9][10][11][12][13]. Tunability of plasmon resonance through the variation of μ, together with a relatively large propagation length and a small localization scale of SPs in the infrared (IR) and terahertz (THz) ranges, are key advantages of graphene SPs over those supported by noble metals like silver and gold [7].…”

Low-loss dielectric-loaded graphene surface plasmon polariton waveguide based biochemical sensor

“…A metal-dielectric waveguide structure supports SPPs that can be used to probe biological substances by measuring the mode amplitude, with a resolution around 0.5-1 lRIU. [9][10][11][12] To improve the performance further, several different SPP waveguide configurations have been considered in recent years. [13][14][15][16][17][18] But most of them do not have long enough propagation length to be practical as a biosensor.…”