Fundamental Surface Plasmon Polariton Mode Research Articles

Strong Purcell effect in deep subwavelength coaxial cavity with GeSn active medium.

We propose a deep subwavelength plasmonic cavity based on a metal-coated coaxial structure with Ge0.9Sn0.1 as the active medium. A fundamental surface plasmon polariton mode is strongly confined on the sidewall of the metal core, with the quality factor up to 5×103 at 10 K. By reducing the cavity dimension to a few nanometers, this cavity mode shows a strong plasmon binding with the mode volume down to 8×10-10 (λ/n)3, and significant size-dependent damping caused by the non-local optical response. The Purcell factor is achieved as high as 2×109 at 10 K and 7×108 at 300 K. This cavity design provides a systematic guideline of scaling down the cavity size and enhancing the Purcell factor. Our theoretical demonstration and understanding of the subwavelength plasmonic cavity represent a significant step toward the large-scale integration of on-chip lasers with a low threshold.

Graphene-based hybrid plasmonic waveguide for highly efficient broadband mid-infrared propagation and modulation.

In this paper, a graphene-based hybrid plasmonic waveguide is proposed for highly efficient broadband surface plasmon polariton (SPP) propagation and modulation at mid-infrared (mid-IR) spectrum. The hybrid plasmonic waveguide is composed of a monolayer graphene sheet in the center, a polysilicon gating layer, and two inner dielectric buffer layers and two outer parabolic-ridged silicon substrates symmetrically placed on both sides of the graphene. Owing to the unique parabolic-ridged waveguide structure, the light-graphene interaction and subwavelength SPPs confinement of the fundamental SPP mode for the hybrid waveguide can be significantly increased. Under the graphene chemical potential of 1.0 eV, the proposed waveguide can achieve outstanding SPP propagation performance with long propagation length of 12.1-16.7 μm and small normalized mode area of ~10-4 in the frequency range of 10-20 THz, exhibiting more than one order smaller in the normalized mode area while remaining the propagation length almost the same level with respect to the hybrid plasmonic waveguide without parabolic ridges. By tuning the graphene chemical potential from 0.1 to 1.0 eV, we demonstrate the waveguide has a modulation depth greater than 51% for the frequency ranging from 10 to 20 THz and reaches a maximum of nearly 100% at the frequency higher than 18 THz. Benefitting from the excellent broadband mid-IR propagation and modulation performance, the graphene-based hybrid plasmonic waveguide may open up a new way for various mid-IR waveguides, modulators, interconnects and optoelectronic devices.

Femtosecond Pulse Propagation through Au and Ag Nanowires

We examine the pulse reshaping of femtosecond pulses propagating through the fundamental surface plasmon polariton mode guided along Au and Ag nanowires. It is observed that the contribution of loss dispersion of the mode to the total dispersion is extremely significant and might exceed the contribution of the group velocity dispersion. In the case of Ag nanowires, beyond a certain critical wavelength, depending on the initial pulse width, a characteristic propagation distance is shown to exist, at which the pulse broadening is zero and up to which the pulse gets compressed instead of broadened. A simple analytical expression for zero dispersion distance is also derived giving its dependence on the initial pulse width. The study should find applications in selecting the wavelength of operation, initial pulse width, and the parameters of Au and Ag nanowires used in connection with ultra-short pulse propagation.

Low-Threshold near-Infrared GaAs–AlGaAs Core–Shell Nanowire Plasmon Laser

We demonstrate plasmonic lasing from metal–organic chemical vapor deposition (MOCVD)-grown GaAs–AlGaAs core–shell nanowires (NWs) with subdiffraction limit diameters of ∼150 nm placed directly on a silver thin film. The absence of a low-index dielectric spacer layer between the NW and the metal layer allows for surface plasmon polariton (SPP) lasing using a nonhybridized plasmonic mode. Unlike previously reported plasmonic NW lasers using the fundamental SPP mode, we demonstrate for the first time plasmonic NW lasing under pulsed optical excitation by using the higher order SPP mode. The higher order mode allows us to alleviate the high losses associated with the fundamental plasmonic mode. We observed lasing at temperatures up to 125 K. Our demonstration of a plasmonic laser based on GaAs emitting in the near-infrared region will be useful for the on-chip integration of nanophotonic and electronic devices and the development of GaAs-based plasmonic devices.

Low-threshold optical bistability in metal-nonlinear dielectric multilayer nanostructure

We numerically investigate the optical bistability with highly confined surface plasmon polaritons (SPPs) modes excitation in a metal-nonlinear dielectric multilayer nanostructure. We find that the field distribution forms a standing wave through the excitation of coupled SPPs in nanomultilayers caused by the Fabry-Perot interferometer. In addition, the average field amplitude is increased by a factor of ∼20.6 compared to that of the incident beam. A very low bistability threshold of 2.75 MW/cm2 is obtained with a fundamental SPPs mode excitation at the telecommunication wavelength of 1550 nm.

Polarization detection analysis of dual-channel surface plasmon resonance sensing for silicone oils based on the D-shaped fiber with a central hole

We present and numerically characterize a dual channel surface plasmon resonance (SPR) sensor based on a D-shaped fiber with a central hole for silicone oil detections. The proposed design incorporates two metalized channels to facilitate the simultaneous detection of one group of silicone oils, which can consist of two different species. It has been demonstrated that the p-polarized input light can induce two peaks among surface plasmon resonance places, which come from the coupling between the core-guided mode and the fundamental surface plasmon polariton (SPP) modes at the D-shaped surface and around the central hole surface. However, the s-polarized input light can only induce one peak among surface plasmon resonance places, which comes from the coupling between the core-guided mode and the fundamental SPP mode around the central hole surface. The simulation results show that the characteristic responses of two channels independently correspond to the refractive index variations in the silicone oils with which they are in contact. A maximum sensitivity of 3500nm/RIU (refractive index unit) and 4400nm/RIU are achieved for channel A and B, respectively. This kind of sensor structure and polarization related demodulation method is promising in the simultaneous multi-analytes sensing applications in the future.