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Frontiers of Optoelectronics

Front. Optoelectron.    2014, Vol. 7 Issue (3) : 320-337     DOI: 10.1007/s12200-014-0469-4
REVIEW ARTICLE |
A review of recent progress in plasmon-assisted nanophotonic devices
Jian WANG()
Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China
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Abstract

Plasmonics squeezes light into dimensions far beyond the diffraction limit by coupling the light with the surface collective oscillation of free electrons at the interface of a metal and a dielectric. Plasmonics, referred to as a promising candidate for high-speed and high-density integrated circuits, bridges microscale photonics and nanoscale electronics and offers similar speed of photonic devices and similar dimension of electronic devices. Various types of passive and active surface plasmon polariton (SPP) enabled devices with enhanced deep-subwavelength mode confinement have attracted increasing interest including waveguides, lasers and biosensors. Despite the trade-off between the unavoidable metal absorption loss and extreme light concentration, the ever-increasing research efforts have been devoted to seeking low-loss plasmon-assisted nanophotonic devices with deep-subwavelength mode confinement, which might find potential applications in high-density nanophotonic integration and efficient nonlinear signal processing. In addition, other plasmon-assisted nanophotonic devices might also promote grooming functionalities and applications benefiting from plasmonics.

In this review article, we give a brief overview of our recent progress in plasmon-assisted nanophotonic devices and their wide applications, including long-range hybrid plasmonic slot (LRHPS) waveguide, ultra-compact plasmonic microresonator with efficient thermo-optic tuning, high quality (Q) factor and small mode volume, compact active hybrid plasmonic ring resonator for deep-subwavelength lasing applications, fabricated hybrid plasmonic waveguides for terabit-scale photonic interconnection, and metamaterials-based broadband and selective generation of orbital angular momentum (OAM) carrying vector beams. It is believed that plasmonics opens possible new ways to facilitate next chip-scale key devices and frontier technologies.

Keywords plasmonics      surface plasmon polariton (SPP)      nanophotonic devices      plasmonic waveguide      photonic interconnection      metamaterials     
Corresponding Authors: Jian WANG   
Online First Date: 25 August 2014    Issue Date: 09 September 2014
 Cite this article:   
Jian WANG. A review of recent progress in plasmon-assisted nanophotonic devices[J]. Front. Optoelectron., 2014, 7(3): 320-337.
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http://journal.hep.com.cn/foe/EN/10.1007/s12200-014-0469-4
http://journal.hep.com.cn/foe/EN/Y2014/V7/I3/320
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Fig.1  Typical operation speed and critical device dimension of different chip-scale device technologies (plasmonics, photonics, electronics and the past)
Fig.2  Schematic illustration of field distribution of surface plasmon polariton (SPP) at the interface between a conductor (metal) and a dielectric
Fig.3  Illustration of surface science enabled waveguides (slot, hybrid plasmonic, long-range hybrid plasmonic, long-range DMD, MDM) with their super modes hybridized from the surface modes at the high-contrast-index dielectric-dielectric interface or/and at the metal-dielectric interface. DMD: dielectric-metal-dielectric; MDM: metal-dielectric-metal
Fig.4  Schematic illustration of 3-D structure of the long-range hybrid plasmonic slot (LRHPS) waveguide [31]
Fig.5  Schematic structures of (a) traditional dielectric-metal-dielectric (DMD) waveguide, (d) vertical slot waveguide, (f) proposed long-range hybrid plasmonic slot (LRHPS) waveguide, and distributions of main transverse electric field component Ex for (b) long-range surface plasmon polariton (SPP) mode and (c) short-range SPP mode of DMD waveguide, (e) vertical slot mode of vertical slot waveguide, (g) long-range hybrid (LRH) mode and (h) short-range hybrid (SRH) mode of LRHPS waveguide. The curves sketched in (b), (c), (e), (g) and (h) show the Ex(x,0) distribution in the waveguides. The arrows plotted in the mode field represent the direction and relative amplitude of transverse electric field component Ex [31]
Fig.6  Normalized phase and attenuation constants of the long-range hybrid (LRH) and short-range hybrid (SRH) modes of long-range hybrid plasmonic slot (LRHPS) waveguide. The dotted line corresponds to a conventional hybrid plasmonic waveguide (a silver, a Si-nc slot and a Si strip from left to right on a silica substrate) with a metal width of 300 nm [31]
Fig.7  (a) 3D structure illustration of the designed plasmonic microresonator; (b) energy density distribution and contour plot under certain geometrical parameters [32]
Fig.8  (a) Schematic illustration of 3D structure for the designed active hybrid plasmonic ring resonator; (b) cross section of the hybrid plasmonic ring resonator; energy flux density distributions and contour plots for the hybrid plasmonic (HP) mode (c) and fundamental photonic (PH) mode (d); normalized energy flux density for the HP mode along y direction (e) and r direction (f) [33]
Fig.9  Gap height (Hg) dependence of the Q factor and mode volume at a resonance in the lasing wavelength band of CdS for the hybrid plasmonic (HP) mode and fundamental photonic (PH) mode (Rc = 100 nm, Rr = 800 nm) [33]
Fig.10  Cross section radius (Rc) dependence of (a) effective refractive index (neff) and (b) resonance wavelength for the hybrid plasmonic (HP) and fundamental photonic (PH) modes (Hg = 10 nm, Rr = 800 nm) [33]
Fig.11  Ring radius Rr dependence of (a) Qtotal, Qrad, Qabs, mode volume and (b) Purcell factor and threshold gain for the HP mode (Hg = 5 nm, Rc = 50 nm) [33]
Fig.12  (a) Structure of hybrid plasmonic waveguide; electric field distributions in cross section of the waveguide at (b)WSi = 500 nm and (c) WSi = 300 nm, respectively; (d) evolution of electric field distribution propagating along the waveguide; (e) scanning electron microscopy (SEM) image of fabricated hybrid plasmonic waveguide [34]
Fig.13  (a) Schematic structure of metamaterials for generating orbital angular momentum (OAM)-carrying vector beams; (b) geometric parameters: the radii are ri = (i + 6.3) × 700 nm (i = 0, 1) and the orientation angle is α(φ) = lφ + α0 (l = 2, α0 = 0 as an example) with respect to the x axis. The rectangular aperture has a dimension of 600 nm × 140 nm; (c) illustration of generating OAM-carrying vector beam (OAM charge number: 2, polarization order: 2) [35]
Fig.14  Spatial distributions of phase, power and polarization of generated orbital angular momentum (OAM)-carrying vector beams (σ = 1: left circularly polarized input beam, σ0 = 0: along the direction of e1(φ)) [35]
Fig.15  Wavelength-dependent (a) extinction ratio (ER) and (b) purity for the generation of orbital angular momentum (OAM)-carrying vector beams. Insets in (b) show weight as functions of OAM charge number (left) and polarization order number (right) at 1550 nm [35]
Fig.16  (a) Schematic structure of metamaterials; (b) geometric parameters: the radius of the ring is ri = (2i + 0.3) × 700 nm, where i = 1, 2 and 3. The rectangular aperture has dimensions of 600 nm × 140 nm and an orientation angle of αi(φ) = iφ + αi0 with respect to the x axis [36]
Fig.17  (a) Wavelength-dependent extinction ratio for three OAM-carrying vector beams; (b) dependence of extinction ratio on the initial orientation angle α20 (second ring); (c) spatial distributions of phase, power components and polarization [36]
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