Research Article Designs and Performance Characteristics ...downloads.hindawi.com/journals/ijap/2015/345137.pdfat optical frequencies can exhibit a surface plasmonic char-acter. Nanostructures

Research ArticleDesigns and Performance Characteristics ofCoated Nanotoroid Antennas

Sami Ur Rehman1 Junping Geng1 Richard W Ziolkowski2 Ying Wang3

Xianling Liang1 and Ronghong Jin1

1Department of Electronic Engineering Shanghai Jiao Tong University No 800 Dongchuan Road Shanghai 200240 China2Electrical and Computer Engineering Department University of Arizona 1230 E Speedway Tucson AZ 85721-0104 USA3Ministry of Information of the Navy Command No 19 West Sanhuan Road Beijing 100036 China

Correspondence should be addressed to Junping Geng gengjunpsjtueducn

Received 16 February 2015 Accepted 27 May 2015

Academic Editor Xianming Qing

Copyright copy 2015 Sami Ur Rehman et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

The electromagnetic properties of a toroidal coated nanoparticle (T-CNP) antennawith an active core (dopedwith rare earth erbiumEr3+ ions) are investigated It is demonstrated that the active T-CNP acts as a strong dipole radiator at its resonance frequency whenit is excited by a plane wave or an electric Hertzian dipole (EHD) radiating element It is shown that in comparison to being a passivestructure the planewave scattering cross section of the T-CNP can be increased by nearly 108 dBsm at its resonance frequencywhenit is active Moreover it is further demonstrated that the maximum peak of the power radiated by an EHD element in the presenceof a properly designed active T-CNP is more than 120 dB over its value when radiating in free space that is its Purcell factor is 1012

1 Introduction

Because they behave as negative epsilon (ENG)mediametalsat optical frequencies can exhibit a surface plasmonic char-acter Nanostructures which incorporate metals includingnanoparticles and arrays of them have shown attractiveproperties [1ndash4] for applications in the areas of biology andmedicine [1 4ndash6] efficient solar cells [7ndash9] optical commu-nications [10] high resolutionmicroscopy [11 12] and sensor[1 13] technologies By combining themwith dielectricmediadoped for instance with the rare earth erbium ion Er3+ theresulting nanosized plasmonic particles can be designed toachieve highly subwavelength amplifiers and lasing elements[14ndash16]

Coated nanoparticles (CNP) which consist of sphericalor cylindrical metallic nanoshells surrounding passive andactive dielectric cores as well as their complementary con-figurations have been studied in almost all of their possiblecombinations They can be designed to have novel opticalproperties that are geometrically tunable If the core is filledwith a lossless or lossy dielectric the particle is called a passive

CNP the model of which has been discussed completelyfor example in [13] When a passive CNP is excited by aplane wave its performance can be naturally characterizedby the maximum absorption (ACS) scattering (SCS) andextinction (ECS) cross sections all of which depend on theradius of the core and the thickness of the metal film of thepassiveCNPWhen theCNP is electrically small the resultingradiated power distribution resembles that of a symmetricaldipole excited by the same electromagnetic wave In additionto a variety of studies of exciting passiveCNPs by planewavesthe electric Hertzian dipole (EHD) is another excitationchoice that has also been studied extensively (eg [17])

On the other hand metals at optical frequencies showstrong loss properties which suppress for instance the SCSpeak at the resonance frequency To overcome the intrinsiclosses associated with plasmonic structures gain materialhas been incorporated into the dielectrics composing themThe resulting active CNPs have been studied extensively fortheir use as nanoamplifiers and nanolasers [14ndash16 18ndash23]Theattractive features offered by active CNPs include not onlyradiated power enhancements but also suppression effects

Hindawi Publishing CorporationInternational Journal of Antennas and PropagationVolume 2015 Article ID 345137 11 pageshttpdxdoiorg1011552015345137

2 International Journal of Antennas and Propagation

thmsr

dd

y

xz

(a) Overhead view

y

z x

(b) Lateral view

Figure 1 Basic T-CNP model geometry

[18 23 24] Besides the CNP-based dipole radiators a varietyof other nanoantenna structures have been investigated overthe past few years These include optical dipoles [20 25ndash31]monopoles [32 33] bow-tie nanoantennas [31 34ndash36] Yagi-Uda nanoantennas [37 38] V-shaped nanoantennas [39]dimers as nanoantennas [40ndash44] dipole nanoantennas withmatched loads [45 46] and tunable nanoantennas [47ndash49]

The analyses of many of these basic nanoantenna struc-tures have been based on the solutions of canonical problemsand numerical simulations Many of these structures remainfar from practical realizations because of the lack of the nec-essary fabrication technologies Nonetheless these analysesprovide much needed physical understanding As nanofab-rication techniques become more and more sophisticatedalongwith an increase in desired functionalitymore complexcoated structures (eg [50]) are now being consideredThesemore sophisticated nanostructures have far more complexmaterial and structural characteristics They can be modeledaccurately with proven numerical simulators

In this paper a novel toroidal structure consisting of again impregnated silica core that is surrounded by a silvernanoshell coating is studied Both plane wave and electricHertzian dipole (EHD) excitations are considered It is shownthat both the passive and active electrically small toroidalcoated nanoparticles (T-CNPs) can be designed to be reso-nant and that they radiate a basic dipole mode when they areresonant yielding a strong linearly polarized field Parameterstudies of these designs are used to delineate the variousproperties of these optical nanoantennas especially theirenhancements of the total radiated power

2 T-CNP Model

The basic T-CNP geometry is shown in Figure 1 The core isassumed to be silica (SiO

2) doped with rare earth erbium

Er3+ ions The nanoshell is assumed to be silver The T-CNP

is excited by both plane waves and the fields radiated by anEHD source

21 Numerical Model To simulate the T-CNP design shownin Figure 1 a commercial software package CST MicrowaveStudio was used It is a computational electromagneticssimulation tool set which solves Maxwellrsquos equations in thetime domain based on the finite integration in time (FIT)technique and in the frequency domain based on the finiteelement method (FEM) [51 52] Time domain methodsare most suitable for wide band problems while frequencydomainmethods aremore appropriate for narrow band prob-lems Dispersive effects must be taken into account for anylossy real or artificial materials The silver coating layer hasproperties that can be described by a thickness-dependentDrude model between 200 nm and 1800 nm [14] In partic-ular the permittivity is decomposed into a size-dependentDrude response and an interband transition responseTo incorporate this model into the CST solver it wasexpressed in terms of a basic Drude permittivity in [21] Thegainmodel which had to be implemented in CSTrsquos frequencydomain solver was described in detail in [19 20] The gainmaterial is described in the frequency-domain CST solver bya modified Lorentz model of the permittivity [19 20]

22 Plane Wave Excitation For a plane wave excitation ofthe T-CNP the behavior of the resulting scattered fields canbe described by the scattering (SCS) and absorption (ACS)cross sections The SCS is defined as the total integratedpower contained in the scattered field normalized by theirradiance of the incident field The ACS is defined by the netflux through a surface surrounding the T-CNPnormalized bythe incident field irradiance [20] Using Poyntingrsquos theoremand the total power scattered and absorbed by the structureboth the SCS andACS can be expressed in terms of the ratio ofthe scattered and absorbed powers to the incident irradiance119868inc [20]

International Journal of Antennas and Propagation 3

550 560 570 580 590 600 610 620 630 640 650

Max

imum

scat

terin

g cr

oss s

ectio

n

Frequency (THz)

minus150

minus148

minus146

minus144

minus142

(a)

550 560 570 580 590 600 610 620 630 640 650

Max

imum

abso

rptio

n cr

oss s

ectio

n

Frequency (THz)

minus144

minus142

minus140

minus138

minus136

(b)

Figure 2 Excitation of the passive T-CNP by a plane wave polarized along the axis of the toroid Maximum values of the (a) scattering (SCS)and (b) absorption (ACS) cross sections as a function of the excitation frequency

23 EHD Excitation Similarly the response of the EHD-excited T-CNP system can be characterized by the totalradiated power

119875tot

= lim119878rarrinfin

∯119878

Re 12tot (119903 120579 120593) times

lowast

tot (119903 120579 120593) sdot 119889119878

(1)

where 119878 is a closed surface that completely surrounds theEHD and the scatter This quantity is readily calculatednumerically using a cube surrounding the EHD and T-CNPsystem [21] The total power radiated by an EHD of length119889 and current moment 119901

119904= 1198680119889 alone in free space has the

well-known value [53]

119875EHD =1205780120587

3

10038161003816100381610038161003816100381610038161003816

1199011199041198960

2120587

10038161003816100381610038161003816100381610038161003816

2=1205780120587

3

10038161003816100381610038161003816100381610038161003816

1198680119889

120582

10038161003816100381610038161003816100381610038161003816

2 (2)

where 1205780 and 1198960 are respectively the free space wave impe-dance and wave number The behavior of the EHDT-CNPnanoantenna system can then be described by the radiatedpower ratio that is the Purcell factor

PR =119875tot119875EHD

(3)

3 Results for the Plane Wave Excitation

31 Passive T-CNP Excited by a z-Polarized Plane Wave Thesilver coating layer in Figure 1 has a thickness denoted asdd The inner radius of the torus is denoted as sr The totalthickness of the silver and the passive SiO

2core medium is

denoted as thm The axis of the torus was taken to be alongthe 119911-axis The T-CNP was excited by a vertically polarizedplane wave that is the electric field vector is parallel to the 119911-axis and is propagating along the 119909-axis as shown in Figure 1The incident plane wave field is given as

997888119864 = 119864

0cos (120596119905 minus 119896119909) (4)

The electric field amplitude 1198640is assumed to be 10 Vm

throughout this paper On the basis of previous results andnumerical models used to describe the behaviors of thepassive and active spherical CNPs in [20] and the cylindrical-shaped CNPs (CC-CNPs) in [21] the thickness of the silvercoating was set to dd = 60 nm During the parameter sweepsit was also observed that the peak location of the SCS infrequency changed as the parameters sr and thmwere variedThe maximum SCS and ACS peaks were found to occurfor sr = 11 nm and thm = 41 nm The maximum SCS andACS values for this optimized passive T-CNP as functions ofthe excitation frequency are shown in Figure 2 These resultsdemonstrate that the resonance peak for the SCS is around600THz as expected from prior studies In particular thepeak value of the SCS is minus14224 dBsm at 599 THz

The predicted results of the electric field power densitycurrent density and the electric and magnetic field energydensities for the passive T-CNP at its lowest order resonancefrequency are shown in Figure 3 The total electric fielddistribution as shown in Figure 3(a) is almost symmetricbut is not quite because it also includes the incident fielddistribution It demonstrates that the scattered field generatedby the resonant T-CNP dominates the near-field behaviorThe power flow distribution in Figure 3(b) shows how theresonant T-CNP has an SCS that is much larger than itsgeometrical size It shows the electromagnetic power beingchanneled into the resonant T-CNP from all directions faraway from its middle The bulk currents are shown inFigure 3(c)They are flowing strongly in the silver shell of theresonant T-CNP with a pattern that radiates the fundamentalelectric dipole mode The TM dipole mode of this T-CNPstructure is oriented in the same direction as the polarizationof the incident electric field This feature also explains theelectric field distribution in Figure 3(a) Similar effects areillustrated with the electric and magnetic field energy densitydistributions in Figures 3(d) and 3(e) The generation of theelectric dipole mode at the resonance frequency is again


(a) (b)

(c) (d)

(e)

Figure 3 Simulated field distributions in the 119883-plane at 119891 = 599THz for the passive T-CNP with sr = 11 nm and thm = 41 nm (a) Electricfield (b) power flow (c) current density (d) electric field energy density and (e) magnetic field energy density

confirmed with the three-dimensional (3D) SCS plot givenin Figure 4

32 Active T-CNP Excited by a z-Polarized Plane Wave Theconfiguration for the active T-CNP is geometrically the sameas in the passive case and shown in Figure 1 The thicknessof its silver metal shell is kept the same as that in the passivecase that is dd = 6 nm The excitation source is again the 119911-polarized plane wave given by (4) Thus the T-CNP axis isagain parallel to the electric field of the incident plane waveThe silver model is identical to the one used in the passivecase the gain model is identical to the one used previously in[19ndash22] Following the same steps as those used in the passivecase the maximum response was achieved by optimizing thegeometry and material parameters that is by sweeping theparameters sr and thm the maximum response of the T-CNP was foundThose parameter sweeps (with dd = 60 nm)indicated that the maximum response is achieved with thevalues sr = 11 nm and thm = 43 nm It was also assumedthat the gain medium is depletion-free that is that all atomsin the gain region contribute to the scatteringradiation

process However in reality and because of depletion theactual number of atoms contributing to the gain processmay decrease in time Consequently our simulation resultsrepresent upper (lower) bounds on the scattering responsesof the T-CNPs Furthermore only the coherent responsesof the system are taken into consideration Again in a realexperiment there may be a strong luminescence responsearising from incoherent processes as the active medium ispumpedThis background response can mask small coherentresponses of interest [21] Nevertheless because our modeltakes into account the gain to produce the backgroundresponse levels and our coherent response is several ordersof magnitude above those levels we expect that the predictedsuper resonance responses reported in this work would bereadily observed in any active T-CNP scattering experiments

The simulated maximum values of the SCS and ACSas functions of the excitation frequency for the optimizedgeometry are given in Figure 5 The SCS results shown inFigure 5 indicate that the resonance frequency occurs at59974 THz where the peak SCS value is minus10811 dBsm Thisresult is significantly (sim3413 dBsm) higher than the peak


x y

z

Figure 4 3D plot of the far-field SCS behavior of passive T-CNP at the 599 THz resonance frequency

550 560 570 580 590 600 610 620 630 640 650Frequency (THz)

Max

imum

scat

terin

g cr

oss s

ectio

n

minus154

minus147

minus140

minus133

minus126

minus119

minus112

minus105

sr = 104 thm = 44

sr = 110 thm = 43

sr = 110 thm = 435

sr = 110 thm = 4333

(a)

Frequency (THz)5995 5996 5997 5998 5999 6000

Max

imum

scat

terin

g cr

oss s

ectio

n

minus140

minus133

minus126

minus119

minus112

minus105

sr = 104 thm = 44

sr = 110 thm = 43

sr = 110 thm = 435

sr = 110 thm = 4333

(b)

Frequency (THz)550 560 570 580 590 600 610 620 630 640 650

Max

imum

abso

rptio

n cr

oss s

ectio

n

minus187

minus170

minus153

minus136

sr = 104 thm = 44

sr = 110 thm = 43

sr = 110 thm = 435

sr = 110 thm = 4333

(c)

5990 5995 6000 6005 6010Frequency (THz)

Max

imum

abso

rptio

n cr

oss s

ectio

n

minus187

minus170

minus153

minus136

sr = 104 thm = 44

sr = 110 thm = 43

sr = 110 thm = 435

sr = 110 thm = 4333

(d)

Figure 5 Simulated results for the optimized active T-CNP (a) Maximum SCS values over a large frequency window (b) zoom-in of (a) nearthe resonance frequency and (c) maximum ACS values over a large frequency window (d) zoom-in of (c) near the resonance frequency


(a) (b)

(c) (d)

(e)

Figure 6 Simulated field distributions in the119883-plane at 119891 = 59974 THz for the active T-CNP with sr = 11 nm and thm = 43 nm (a) Electricfield (b) power flow (c) current density (d) electric field energy density and (e) magnetic field energy density

value for the passive case shown in Figure 2 Similarly theACS values also decrease by a similar significant amount(6316 dBsm) when compared with the passive case shown inFigure 2

The simulated distributions of the electric field powerdensity current density and the electric and magnetic fieldenergy densities at the resonant frequency 59974 THz areshown in Figure 6The electric field and power flow distribu-tions in Figures 6(a) and 6(b) respectively along with the far-field 3D SCS pattern given in Figure 7 clearly demonstratethat the active T-CNP is radiating in the electric dipolemode at its resonance frequency but at much higher levels ascompared to the passive case values Figure 6(c) indicates thata large current density is generated in the core and a strongcurrent loop is formed in the surrounding metal shell atresonance The resonant current in the core is a combinationof the conduction anddisplacement currentsThe conductioncurrent occurs in the core of the active T-CNP because ofthe conductivity (associated with the loss term) introducedby the gain model This behavior in the active T-CNP is

xy

z

Figure 7 3D plot of the far-field SCS behavior of the active T-CNPat its resonance frequency 59974 THz


a significant contrast to the much weaker currents that onlyflow in the metallic shell at nonresonant frequencies and inall of the passive cases As a consequence the strong currentsdominate the radiation process and as shown in Figure 6(b)the power is clearly flowing away from the center of T-CNPThe electric and magnetic field energy distributions shownrespectively in Figures 6(d) and 6(e) also confirm the electricdipole nature of the behavior of active T-CNP at its resonancefrequency

Note that when the amplification becomes significantlylarge as it does at the resonance frequency the electric fieldsin the core region are extremely large The T-CNP as anelectrically small resonator like its spherical and cylindricalcounterparts is facilitated and formed by the juxtapositionof the ENG and regular double positive (DPS) materials Themetallic coated core is purposely chosen to emphasize thisresonator effect The complementary structure has a muchweaker field confinement and thus requires more gain toachieve amplification [54] Because of these large fields andthe presence of the effective conductivity introduced by theloss component of the gain model the conduction currentsare large in the core as noted previously Furthermorebecause of the difference in signs of the permittivity in thecore and in the shell the current densities in both regions areof opposite direction as illustrated in Figure 6(c)

33 T-CNP Excited by an EHD After establishing the res-onance frequency and the fundamental dipole radiationprocess of the passive and active T-CNP under plane waveexcitation the behavior of the active structure was examinedusing an EHD as the source of excitation The impact on theT-CNP nanoamplifier performance arising from differencesin the location of the EHD was of particular interest It wasexpected that the outcomes of these studies would accentuatehow well the T-CNP would act as a nanoamplifier in a nano-sensor application For instance a fluorescing atom ormolecule would act as a dipole in its transition from anexcited to a lower energy state [20 21] By tuning the reso-nance of the T-CNP to the corresponding transition fre-quency one would then achieve a significant amplificationof the fluorescent response of that atom or molecule Onthe other hand if the atom or molecule would fall intothe center of the toroid or just outside of it the T-CNPwould still produce a significantly amplified emission signalIf the amplification level was essentially independent of thelocation of the effective EHD theT-CNPwouldmake an idealnanoamplifier for the resulting nanosensor system

The dimensions and material properties of the active T-CNP were kept exactly the same for the EHD excitation asthose utilized in the optimized plane wave excitation casethat is sr = 11 nm thm = 43 nm and dd = 60 nm It wasexpected that the resonance frequency associated with theEHD excitation would be the same or only slightly differentfrom its plane wave excitation value The fluorescing emitterwas assumed to be an EHD oriented along the axis of thetoroid to achieve its maximum response It was realizednumerically as a small 119911-directed current element (orientedparallel to the axis of the toroid) located at all of the locations

A B C D E

z

x

Figure 8 The EHD locations along the horizontal center lineof the toroidal structure which were scanned to determine theimpact of the source location on the active T-CNP performancecharacteristics As illustrated the EHD is oriented along the axis ofthe toroid

shown in Figure 8 The current dipole moment of the EHDwas held fixed in all cases to 119868

0119889 = 2 times 10

minus12 A-m Not onlywere the center-of-the-toroid and just outside-the-toroidlocations considered but also locations in the shell andwithin the core Again these were selected as comparisoncases to establish how well the active T-CNP would act as ananoamplifier

The response of the active T-CNP excited by the EHDwascharacterized by the total power radiated by the system usinga cube surrounding the overall (EHD and T-CNP) system[21] The power radiated by the EHD alone was obtained inthe same manner The calculated radiated power ratios (3)for the EHD location points A B C D and E indicated inFigure 8 as functions of the excitation frequency are shownin Figure 9 The EHD locations starting from the geometriccenter of the T-CNP were precisely 119909 = 0 (A) 119909 = 14 nm(B) 119909 = 325 nm (C) 119909 = 435 nm (D) and 119909 = 57 nm (E)It is clear from these radiated power ratio results that thereis a large resonance peak close to 600 THz In fact all of theresonances occur at 59974 THz the same frequency as foundfor the plane wave excitation caseThemaximum value of theradiated power ratio is 12847 dB when the T-CNP is excitedby the EHD at point D inside the core but offset from the corecenter and closer to the inside wall of the silver shellThis off-center result is very similar to the EHD results obtained forthe active cylindrical CNP [21] The peak value at point A is11314 dB at point E is 11221 dB While these peak values arenot as large as the one obtained when the EHD was locatedin the core they are nonetheless very large and emphasizethe usefulness of the active T-CNP as a nanoamplifier As onewould expect the peak values decrease as the EHD locationmoves further away for the T-CNP where the coupling of theEHD to it would be much less

The field distributions and vector fields when the EHD islocated at the offset point D and excites the active T-CNP atits resonance frequency 59974 THz are shown in Figure 10Again the electric field power density current density andthe electric and magnetic field energy densities are displayedNote that they are all symmetric and have the anticipateddipole mode form The local electric field in Figure 10(a) hasthe expected dipolar form The power is radiating stronglyoutward away from the active T-CNP in Figure 10(b) Bulkcurrents at the resonance frequency are again clearly flowingin the gain material in Figure 10(c) as well as in the opposite


707580859095

100105110115120125130

Pow

er ra

tio (d

B)

Frequency (THz)585 588 591 594 597 600 603 606 609 612 615

x = 0

x = 325

x = 14

x = 4325

x = 57

(a)Po

wer

ratio

(dB)

Frequency (THz)

70

80

90

100

110

120

130

5994 5995 5996 5997 5998 5999 6000

x = 0

x = 325

x = 14

x = 4325

x = 57

(b)

Figure 9 Results for radiated power ratio (Purcell factor) for the active T-CNP as a function of the frequency for the different EHD locationsshown in Figure 8 (a) Large frequency window and (b) zoom-in near the resonance frequency

(a) (b)

(c) (d)

(e)

Figure 10 Simulated field distributions in the119883-plane at 119891 = 59974 THz for the active T-CNP excited with the EHD at position D with sr =11 nm and thm = 43 nm (a) Electric field (b) power flow (c) current density (d) electric field energy density and (e) magnetic field energydensity


xy

z

Figure 11 3D plot of the far-field behavior at 119891 = 59974 THz ofT-CNP excited by an EHD at point D

direction in the silver shell The field energy densities areconcentrated in and around the gain-impregnated core Asshown in Figure 11 the 3D directivity pattern is clearly aresult of the electric dipole mode dominance of the radiationprocess The same behaviors are realized for all of thelocations AndashE of the EHD

4 Conclusions

An investigation of the electromagnetic behavior of passiveand active toroid shaped and coated nanoparticles was pre-sented Using an experimentally validated frequency domainsimulator results for the plane wave excitation of both passiveand active T-CNPs were considered It was shown that theactive T-CNP dramatically enhances the SCS and ACS valuesat its resonance frequency An EHD excitation of the active T-CNPwas also considered and studied by varying the locationsof the EHD It was demonstrated that whether the activeT-CNPs were excited by plane wave or EHD fields theycould be designed to be resonant and their radiated fieldresponse was that of the fundamental electric dipole modeThe scattering cross section for the optimized T-CNP excitedby a plane wave was increased by 108 dBsm at resonance fromthe background The maximum of the total radiated powerratio (Purcell factor) for the corresponding EHD excitationwas increased by 120 dB These results confirm the potentialusefulness of active T-CNPs for nanosensor applications

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

This work was supported by the National Natural ScienceFoundation (61201058 61471240) the Research and Inno-vation Project of Shanghai Education Commission (12Z1120

30001) and the Scientific Research Foundation for ReturnedOverseas Chinese Scholars the State Quality InspectionAdministration of Science and Technology Project underGrant 2013QK127 State Education Ministry and the Projectof ldquoSMC Excel lent Young Facultyrdquo

References

[1] P K Jain X Huang I H El-Sayed and M A El-Sayed ldquoNoblemetals on the nanoscale optical and photo thermal proper-ties and some applications in imaging sensing biology andmedicinerdquo Accounts of Chemical Research vol 41 no 12 pp1578ndash1586 2008

[2] J A Gordon and R W Ziolkowski ldquoCNP optical metamateri-alsrdquo Optics Express vol 16 no 9 pp 6692ndash6716 2008

[3] B Garcıa-Camara F Moreno F Gonzalez and O J F MartinldquoLight scattering by an array of electric and magnetic nanopar-ticlesrdquo Optics Express vol 18 no 10 pp 10001ndash10015 2010

[4] N J Halas ldquoPlasmonics an emerging field fostered by nanolettersrdquo Nano Letters vol 10 no 10 pp 3816ndash3822 2010

[5] A W H Lin N A Lewinski J L West N J Halas and RA Drezek ldquoOptically tunable nanoparticle contrast agents forearly cancer detection model-based analysis of gold nano-shellsrdquo Journal of Biomedical Optics vol 10 no 6 Article ID064035 2005

[6] X Liu and Q Huo ldquoA washing-free and amplification-freeone-step homogeneous assay for protein detection using goldnanoparticle probes and dynamic light scatteringrdquo Journal ofImmunological Methods vol 349 no 1-2 pp 38ndash44 2009

[7] K R Catchpole and A Polman ldquoPlasmonic solar cellsrdquo OpticsExpress vol 16 no 26 pp 21793ndash21800 2008

[8] R A Pala J White E Barnard J Liu and M L BrongersmaldquoDesign of plasmonic thin-film solar cells with broadbandabsorption enhancementsrdquo Advanced Materials vol 21 no 34pp 3504ndash3509 2009

[9] H A Atwater andA Polman ldquoPlasmonics for improved photo-voltaic devicesrdquoNatureMaterials vol 9 no 3 pp 205ndash213 2010

[10] G Shvets S Trendafilov J B Pendry and A Sarychev ldquoGuid-ing focusing and sensing on the subwavelength scale usingmetallic wire arraysrdquo Physical Review Letters vol 99 no 5Article ID 053903 4 pages 2007

[11] A Grbic L Jiang and R Merlin ldquoNear-field plates subdiffrac-tion focusing with patterned surfacesrdquo Science vol 320 no5875 pp 511ndash513 2008

[12] S Kawata Y Inouye and P Verma ldquoPlasmonics for near-fieldnano-imaging and superlensingrdquoNature Photonics vol 3 no 7pp 388ndash394 2009

[13] J A Gordon and R W Ziolkowski ldquoInvestigating functional-ized active coated nano-particles for use in nano-sensing appli-cationsrdquo Optics Express vol 15 no 20 pp 12562ndash12582 2007

[14] J A Gordon and R W Ziolkowski ldquoThe design and simulatedperformance of a coated nano-particle laserrdquoOptics Express vol15 no 5 pp 2622ndash2653 2007

[15] M I Stockman ldquoThe spaser as a nanoscale quantum generatorand ultrafast amplifierrdquo Journal of Optics A Pure and AppliedOptics vol 12 no 2 Article ID 024004 2010

[16] I Liberal I Ederra R Gonzalo and R W Ziolkowski ldquoInduc-tion theorem analysis of resonant nanoparticles design of aHuygens source nanoparticle laserrdquo Physical Review Appliedvol 1 no 4 Article ID 044002 2014


[17] S Arslanagic R W Ziolkowski and O Breinbjerg ldquoRadiationproperties of an electric Hertzian dipole located near-by con-centric metamaterial spheresrdquo Radio Science vol 42 Article IDRS6S16 2007

[18] S Arslanagic and R W Ziolkowski ldquoActive coated nano-par-ticle excited by an arbitrarily located electric Hertzian dipole-resonance and transparency effectsrdquo Journal of Optics A Pureand Applied Optics vol 12 no 2 Article ID 024014 2010

[19] J Geng R W Ziolkowski S Cambell R Jin and X LiangldquoStudies of nanometer antennas incorporating gain materialusing CSTrdquo in Proceedings of the IEEE International Symposiumon Antennas and Propagation and USNCURSI National RadioScience Meeting (APSURSI rsquo11) pp 1624ndash1627 Spokane WashUSA July 2011

[20] J Geng R W Ziolkowski R Jin and X Liang ldquoNumericalstudy of the near-field and far-field properties of active opencylindrical coated nanoparticle antennasrdquo IEEE Photonics Jour-nal vol 3 no 6 pp 1093ndash1110 2011

[21] J Geng R W Ziolkowski R Jin and X Liang ldquoDetailed per-formance characteristics of vertically polarized cylindricalactive coated nano-particle antennasrdquo Radio Science vol 47Article ID RS2013 2012

[22] J Geng D Chen R Jin X Liang J Tang and RW ZiolkowskildquoStudy of active coated nano-toroid antennasrdquo in Proceedings ofthe International Workshop on Antenna Technology (iWAT rsquo13)pp 154ndash157 Karlsruhe Germany March 2013

[23] S Arslanagic and R W Ziolkowski ldquoInfluence of active nanoparticle size and material composition on multiple quan-tum emitter enhancements their enhancement and jammingeffectsrdquo Progress in Electromagnetics Research vol 149 pp 85ndash99 2014

[24] S Arslanagic and R W Ziolkowski ldquoJamming of quantumemitters by active coated nan-oparticlesrdquo IEEE Journal onSelected Topics in Quantum Electronics vol 19 no 3 Article ID4800506 2013

[25] J N Farahani D W Pohl H-J Eisler and B Hecht ldquoSinglequantum dot coupled to a scanning optical antenna a tunablesuperemitterrdquo Physical Review Letters vol 95 no 1 Article ID017402 2005

[26] E Cubukcu E A Kort K B Crozier and F Capasso ldquoPlas-monic laser antennardquo Applied Physics Letters vol 89 no 9Article ID 093120 2006

[27] S Kuhn U Hkanson L Rogobete and V SandoghdarldquoEnhancement of single-molecule fluorescence using a goldnanoparticle as an optical nano antennardquo Physical Review Let-ters vol 97 no 1 Article ID 017402 2006

[28] L Novotny ldquoEffective wavelength scaling for optical antennasrdquoPhysical Review Letters vol 98 no 26 Article ID 266802 2007

[29] J AizpuruaGWBryant L J Richter F J Garcıa deAbajo B KKelley and T Mallouk ldquoOptical properties of coupled metallicnanorods for field-enhanced spectroscopyrdquo Physical Review Bvol 71 no 23 Article ID 235420 pp 235ndash420 2005

[30] P Muhlschlegel H-J Eisler O J F Martin B Hecht and DWPohl ldquoResonant optical antennasrdquo Science vol 308 no 5728pp 1607ndash1609 2005

[31] H Fischer andO J FMartin ldquoEngineering the optical responseof plasmonic nanoantennasrdquo Optics Express vol 16 no 12 pp9144ndash9154 2008

[32] TH Taminiau R JMoerland F B Segerink L Kuipers andNF van Hulst ldquo1205824 Resonance of an optical monopole antennaprobed by singlemolecule fluorescencerdquoNano Letters vol 7 no1 pp 28ndash33 2007

[33] T H Taminiau F B Segerink andN F vanHulst ldquoAmonopoleantenna at optical frequencies single-molecule near-field mea-surementsrdquo IEEE Transactions on Antennas and Propagationvol 55 no 11 pp 3010ndash3017 2007

[34] D P Fromm A Sundaramurthy P James Schuck G Kinoand W E Moerner ldquoGap-dependent optical coupling of singlelsquobowtiersquo nanoantennas resonant in the visiblerdquoNano Letters vol4 no 5 pp 957ndash961 2004

[35] LWang SM Uppuluri E X Jin and X Xu ldquoNanolithographyusing high transmission nanoscale bowtie aperturesrdquo NanoLetters vol 6 no 3 pp 361ndash364 2006

[36] A Sundaramurthy P J Schuck N R Conley D P Fromm GS Kino and W E Moerner ldquoToward nanometer-scale opticalphotolithography utilizing the near-field of bowtie opticalnanoantennasrdquo Nano Letters vol 6 no 3 pp 355ndash360 2006

[37] J Li A Salandrino and N Engheta ldquoShaping light beams inthe nanometer scale a Yagi-Uda nano antenna in the opticaldomainrdquo Physical Review B vol 76 no 24 Article ID 2454032007

[38] T H Taminiau F D Stefani and N F Van Hulst ldquoEnhanceddirectional excitation and emission of single emitters by a nano-optical Yagi-Uda antennardquo Optics Express vol 16 no 14 pp10858ndash10866 2008

[39] J Yang J Zhang XWu and Q Gong ldquoElectric field enhancingproperties of the V-shaped optical resonant antennasrdquo OpticsExpress vol 15 no 25 pp 16852ndash16859 2007

[40] L Rogobete F Kaminski M Agio and V Sandoghdar ldquoDesignof plasmonic nanoantennae for enhancing spontaneous emis-sionrdquo Optics Letters vol 32 no 12 pp 1623ndash1625 2007

[41] O L Muskens V Giannini J A Sanchez-Gil and J G RivasldquoStrong enhancement of the radiative decay rate of emitters bysingle plasmonic nanoantennasrdquo Nano Letters vol 7 no 9 pp2871ndash2875 2007

[42] R M Bakker A Boltasseva Z Liu et al ldquoNear-field excitationof nanoantenna resonancerdquo Optics Express vol 15 no 21 pp13682ndash13688 2007

[43] O L Muskens V Giannini J A Sanchez-Gil and J GomezRivas ldquoOptical scattering resonances of single and coupleddimer plasmonic nanoantennasrdquo Optics Express vol 15 no 26pp 17736ndash17746 2007

[44] A Alu and N Engheta ldquoHertzian plasmonic nanodimer as anefficient optical nanoantennardquo Physical Review BmdashCondensedMatter and Materials Physics vol 78 no 19 Article ID 1951112008

[45] A Alu and N Engheta ldquoTuning the scattering response ofoptical nanoantennaswith nanocircuit loadsrdquoNature Photonicsvol 2 no 5 pp 307ndash310 2008

[46] M L Brongersma ldquoPlasmonics engineering optical nanoan-tennasrdquo Nature Photonics vol 2 no 5 pp 270ndash272 2008

[47] G Leveque and O J F Martin ldquoTunable composite nanoparti-cle for plasmonicsrdquoOptics Letters vol 31 no 18 pp 2750ndash27522006

[48] K H Su Q H Wei and X Zhang ldquoTunable and augmentedplasmon resonances of AuSiO

2Au nanodisksrdquoApplied Physics

Letters vol 88 no 6 Article ID 063118 2006[49] JMerleinMKahl A Zuschlag et al ldquoNanomechanical control

of an optical antennardquo Nature Photonics vol 2 no 4 pp 230ndash233 2008

[50] B Khlebtsov E Panfilova V Khanadeev et al ldquoNanocom-posites containing silica-coated gold-silver nanocages and Yb-24-dimethoxyhematoporphyrin multifunctional capability of


IR-luminescence detection photosensitization and photother-molysisrdquo ACS Nano vol 5 no 9 pp 7077ndash7089 2011

[51] httpswwwcstcomProductsCSTMWSSolvers[52] T Weiland ldquoTime domain electromagnetic field computation

with finite difference methodsrdquo International Journal of Numer-icalModelling ElectronicNetworks Devices and Fields vol 9 no4 pp 295ndash319 1996

[53] C A Balanis AntennaTheory Analysis and Design JohnWileyamp Sons New York NY USA 3rd edition 2005

[54] S D Campbell and R W Ziolkowski ldquoImpact of strong local-ization of the incident power density on the nano-amplifiercharacteristics of active coated nano-particlesrdquo Optics Commu-nications vol 285 no 16 pp 3341ndash3352 2012

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014


Active and Passive Electronic Components

Control Scienceand Engineering

Journal of



RotatingMachinery


Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design



Shock and Vibration


Civil EngineeringAdvances in

Acoustics and VibrationAdvances in



Electrical and Computer Engineering

Journal of

Advances inOptoElectronics


Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of


Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014


Chemical EngineeringInternational Journal of Antennas and

Propagation




Navigation and Observation



DistributedSensor Networks



thmsr

dd

y

xz

(a) Overhead view

y

z x

(b) Lateral view

Figure 1 Basic T-CNP model geometry

[18 23 24] Besides the CNP-based dipole radiators a varietyof other nanoantenna structures have been investigated overthe past few years These include optical dipoles [20 25ndash31]monopoles [32 33] bow-tie nanoantennas [31 34ndash36] Yagi-Uda nanoantennas [37 38] V-shaped nanoantennas [39]dimers as nanoantennas [40ndash44] dipole nanoantennas withmatched loads [45 46] and tunable nanoantennas [47ndash49]

The analyses of many of these basic nanoantenna struc-tures have been based on the solutions of canonical problemsand numerical simulations Many of these structures remainfar from practical realizations because of the lack of the nec-essary fabrication technologies Nonetheless these analysesprovide much needed physical understanding As nanofab-rication techniques become more and more sophisticatedalongwith an increase in desired functionalitymore complexcoated structures (eg [50]) are now being consideredThesemore sophisticated nanostructures have far more complexmaterial and structural characteristics They can be modeledaccurately with proven numerical simulators

In this paper a novel toroidal structure consisting of again impregnated silica core that is surrounded by a silvernanoshell coating is studied Both plane wave and electricHertzian dipole (EHD) excitations are considered It is shownthat both the passive and active electrically small toroidalcoated nanoparticles (T-CNPs) can be designed to be reso-nant and that they radiate a basic dipole mode when they areresonant yielding a strong linearly polarized field Parameterstudies of these designs are used to delineate the variousproperties of these optical nanoantennas especially theirenhancements of the total radiated power

2 T-CNP Model

The basic T-CNP geometry is shown in Figure 1 The core isassumed to be silica (SiO

2) doped with rare earth erbium

Er3+ ions The nanoshell is assumed to be silver The T-CNP

is excited by both plane waves and the fields radiated by anEHD source

21 Numerical Model To simulate the T-CNP design shownin Figure 1 a commercial software package CST MicrowaveStudio was used It is a computational electromagneticssimulation tool set which solves Maxwellrsquos equations in thetime domain based on the finite integration in time (FIT)technique and in the frequency domain based on the finiteelement method (FEM) [51 52] Time domain methodsare most suitable for wide band problems while frequencydomainmethods aremore appropriate for narrow band prob-lems Dispersive effects must be taken into account for anylossy real or artificial materials The silver coating layer hasproperties that can be described by a thickness-dependentDrude model between 200 nm and 1800 nm [14] In partic-ular the permittivity is decomposed into a size-dependentDrude response and an interband transition responseTo incorporate this model into the CST solver it wasexpressed in terms of a basic Drude permittivity in [21] Thegainmodel which had to be implemented in CSTrsquos frequencydomain solver was described in detail in [19 20] The gainmaterial is described in the frequency-domain CST solver bya modified Lorentz model of the permittivity [19 20]

22 Plane Wave Excitation For a plane wave excitation ofthe T-CNP the behavior of the resulting scattered fields canbe described by the scattering (SCS) and absorption (ACS)cross sections The SCS is defined as the total integratedpower contained in the scattered field normalized by theirradiance of the incident field The ACS is defined by the netflux through a surface surrounding the T-CNPnormalized bythe incident field irradiance [20] Using Poyntingrsquos theoremand the total power scattered and absorbed by the structureboth the SCS andACS can be expressed in terms of the ratio ofthe scattered and absorbed powers to the incident irradiance119868inc [20]


550 560 570 580 590 600 610 620 630 640 650

Max

imum

scat

terin

g cr

oss s

ectio

n

Frequency (THz)

minus150

minus148

minus146

minus144

minus142

(a)

550 560 570 580 590 600 610 620 630 640 650

Max

imum

abso

rptio

n cr

oss s

ectio

n

Frequency (THz)

minus144

minus142

minus140

minus138

minus136

(b)



119875tot


∯119878

Re 12tot (119903 120579 120593) times

lowast

tot (119903 120579 120593) sdot 119889119878

(1)




119875EHD =1205780120587

3

10038161003816100381610038161003816100381610038161003816

1199011199041198960

2120587

10038161003816100381610038161003816100381610038161003816

2=1205780120587

3

10038161003816100381610038161003816100381610038161003816

1198680119889

120582

10038161003816100381610038161003816100381610038161003816

2 (2)


PR =119875tot119875EHD

(3)



2core medium is


997888119864 = 119864

0cos (120596119905 minus 119896119909) (4)





(a) (b)

(c) (d)

(e)







x y

z


550 560 570 580 590 600 610 620 630 640 650Frequency (THz)

Max

imum

scat

terin

g cr

oss s

ectio

n

minus154

minus147

minus140

minus133

minus126

minus119

minus112

minus105

sr = 104 thm = 44

sr = 110 thm = 43

sr = 110 thm = 435

sr = 110 thm = 4333

(a)

Frequency (THz)5995 5996 5997 5998 5999 6000

Max

imum

scat

terin

g cr

oss s

ectio

n

minus140

minus133

minus126

minus119

minus112

minus105

sr = 104 thm = 44

sr = 110 thm = 43

sr = 110 thm = 435

sr = 110 thm = 4333

(b)

Frequency (THz)550 560 570 580 590 600 610 620 630 640 650

Max

imum

abso

rptio

n cr

oss s

ectio

n

minus187

minus170

minus153

minus136

sr = 104 thm = 44

sr = 110 thm = 43

sr = 110 thm = 435

sr = 110 thm = 4333

(c)

5990 5995 6000 6005 6010Frequency (THz)

Max

imum

abso

rptio

n cr

oss s

ectio

n

minus187

minus170

minus153

minus136

sr = 104 thm = 44

sr = 110 thm = 43

sr = 110 thm = 435

sr = 110 thm = 4333

(d)



(a) (b)

(c) (d)

(e)




xy

z







A B C D E

z

x



0119889 = 2 times 10





707580859095

100105110115120125130

Pow

er ra

tio (d

B)

Frequency (THz)585 588 591 594 597 600 603 606 609 612 615

x = 0

x = 325

x = 14

x = 4325

x = 57

(a)Po

wer

ratio

(dB)

Frequency (THz)

70

80

90

100

110

120

130

5994 5995 5996 5997 5998 5999 6000

x = 0

x = 325

x = 14

x = 4325

x = 57

(b)


(a) (b)

(c) (d)

(e)



xy

z



4 Conclusions




Acknowledgments



References






























































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










550 560 570 580 590 600 610 620 630 640 650

Max

imum

scat

terin

g cr

oss s

ectio

n

Frequency (THz)

minus150

minus148

minus146

minus144

minus142

(a)

550 560 570 580 590 600 610 620 630 640 650

Max

imum

abso

rptio

n cr

oss s

ectio

n

Frequency (THz)

minus144

minus142

minus140

minus138

minus136

(b)



119875tot


∯119878

Re 12tot (119903 120579 120593) times

lowast

tot (119903 120579 120593) sdot 119889119878

(1)




119875EHD =1205780120587

3

10038161003816100381610038161003816100381610038161003816

1199011199041198960

2120587

10038161003816100381610038161003816100381610038161003816

2=1205780120587

3

10038161003816100381610038161003816100381610038161003816

1198680119889

120582

10038161003816100381610038161003816100381610038161003816

2 (2)


PR =119875tot119875EHD

(3)



2core medium is


997888119864 = 119864

0cos (120596119905 minus 119896119909) (4)





(a) (b)

(c) (d)

(e)







x y

z


550 560 570 580 590 600 610 620 630 640 650Frequency (THz)

Max

imum

scat

terin

g cr

oss s

ectio

n

minus154

minus147

minus140

minus133

minus126

minus119

minus112

minus105

sr = 104 thm = 44

sr = 110 thm = 43

sr = 110 thm = 435

sr = 110 thm = 4333

(a)

Frequency (THz)5995 5996 5997 5998 5999 6000

Max

imum

scat

terin

g cr

oss s

ectio

n

minus140

minus133

minus126

minus119

minus112

minus105

sr = 104 thm = 44

sr = 110 thm = 43

sr = 110 thm = 435

sr = 110 thm = 4333

(b)

Frequency (THz)550 560 570 580 590 600 610 620 630 640 650

Max

imum

abso

rptio

n cr

oss s

ectio

n

minus187

minus170

minus153

minus136

sr = 104 thm = 44

sr = 110 thm = 43

sr = 110 thm = 435

sr = 110 thm = 4333

(c)

5990 5995 6000 6005 6010Frequency (THz)

Max

imum

abso

rptio

n cr

oss s

ectio

n

minus187

minus170

minus153

minus136

sr = 104 thm = 44

sr = 110 thm = 43

sr = 110 thm = 435

sr = 110 thm = 4333

(d)



(a) (b)

(c) (d)

(e)




xy

z







A B C D E

z

x



0119889 = 2 times 10





707580859095

100105110115120125130

Pow

er ra

tio (d

B)

Frequency (THz)585 588 591 594 597 600 603 606 609 612 615

x = 0

x = 325

x = 14

x = 4325

x = 57

(a)Po

wer

ratio

(dB)

Frequency (THz)

70

80

90

100

110

120

130

5994 5995 5996 5997 5998 5999 6000

x = 0

x = 325

x = 14

x = 4325

x = 57

(b)


(a) (b)

(c) (d)

(e)



xy

z



4 Conclusions




Acknowledgments



References






























































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










(a) (b)

(c) (d)

(e)







x y

z


550 560 570 580 590 600 610 620 630 640 650Frequency (THz)

Max

imum

scat

terin

g cr

oss s

ectio

n

minus154

minus147

minus140

minus133

minus126

minus119

minus112

minus105

sr = 104 thm = 44

sr = 110 thm = 43

sr = 110 thm = 435

sr = 110 thm = 4333

(a)

Frequency (THz)5995 5996 5997 5998 5999 6000

Max

imum

scat

terin

g cr

oss s

ectio

n

minus140

minus133

minus126

minus119

minus112

minus105

sr = 104 thm = 44

sr = 110 thm = 43

sr = 110 thm = 435

sr = 110 thm = 4333

(b)

Frequency (THz)550 560 570 580 590 600 610 620 630 640 650

Max

imum

abso

rptio

n cr

oss s

ectio

n

minus187

minus170

minus153

minus136

sr = 104 thm = 44

sr = 110 thm = 43

sr = 110 thm = 435

sr = 110 thm = 4333

(c)

5990 5995 6000 6005 6010Frequency (THz)

Max

imum

abso

rptio

n cr

oss s

ectio

n

minus187

minus170

minus153

minus136

sr = 104 thm = 44

sr = 110 thm = 43

sr = 110 thm = 435

sr = 110 thm = 4333

(d)



(a) (b)

(c) (d)

(e)




xy

z







A B C D E

z

x



0119889 = 2 times 10





707580859095

100105110115120125130

Pow

er ra

tio (d

B)

Frequency (THz)585 588 591 594 597 600 603 606 609 612 615

x = 0

x = 325

x = 14

x = 4325

x = 57

(a)Po

wer

ratio

(dB)

Frequency (THz)

70

80

90

100

110

120

130

5994 5995 5996 5997 5998 5999 6000

x = 0

x = 325

x = 14

x = 4325

x = 57

(b)


(a) (b)

(c) (d)

(e)



xy

z



4 Conclusions




Acknowledgments



References






























































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










x y

z


550 560 570 580 590 600 610 620 630 640 650Frequency (THz)

Max

imum

scat

terin

g cr

oss s

ectio

n

minus154

minus147

minus140

minus133

minus126

minus119

minus112

minus105

sr = 104 thm = 44

sr = 110 thm = 43

sr = 110 thm = 435

sr = 110 thm = 4333

(a)

Frequency (THz)5995 5996 5997 5998 5999 6000

Max

imum

scat

terin

g cr

oss s

ectio

n

minus140

minus133

minus126

minus119

minus112

minus105

sr = 104 thm = 44

sr = 110 thm = 43

sr = 110 thm = 435

sr = 110 thm = 4333

(b)

Frequency (THz)550 560 570 580 590 600 610 620 630 640 650

Max

imum

abso

rptio

n cr

oss s

ectio

n

minus187

minus170

minus153

minus136

sr = 104 thm = 44

sr = 110 thm = 43

sr = 110 thm = 435

sr = 110 thm = 4333

(c)

5990 5995 6000 6005 6010Frequency (THz)

Max

imum

abso

rptio

n cr

oss s

ectio

n

minus187

minus170

minus153

minus136

sr = 104 thm = 44

sr = 110 thm = 43

sr = 110 thm = 435

sr = 110 thm = 4333

(d)



(a) (b)

(c) (d)

(e)




xy

z







A B C D E

z

x



0119889 = 2 times 10





707580859095

100105110115120125130

Pow

er ra

tio (d

B)

Frequency (THz)585 588 591 594 597 600 603 606 609 612 615

x = 0

x = 325

x = 14

x = 4325

x = 57

(a)Po

wer

ratio

(dB)

Frequency (THz)

70

80

90

100

110

120

130

5994 5995 5996 5997 5998 5999 6000

x = 0

x = 325

x = 14

x = 4325

x = 57

(b)


(a) (b)

(c) (d)

(e)



xy

z



4 Conclusions




Acknowledgments



References






























































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










(a) (b)

(c) (d)

(e)




xy

z







A B C D E

z

x



0119889 = 2 times 10





707580859095

100105110115120125130

Pow

er ra

tio (d

B)

Frequency (THz)585 588 591 594 597 600 603 606 609 612 615

x = 0

x = 325

x = 14

x = 4325

x = 57

(a)Po

wer

ratio

(dB)

Frequency (THz)

70

80

90

100

110

120

130

5994 5995 5996 5997 5998 5999 6000

x = 0

x = 325

x = 14

x = 4325

x = 57

(b)


(a) (b)

(c) (d)

(e)



xy

z



4 Conclusions




Acknowledgments



References






























































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation














A B C D E

z

x



0119889 = 2 times 10





707580859095

100105110115120125130

Pow

er ra

tio (d

B)

Frequency (THz)585 588 591 594 597 600 603 606 609 612 615

x = 0

x = 325

x = 14

x = 4325

x = 57

(a)Po

wer

ratio

(dB)

Frequency (THz)

70

80

90

100

110

120

130

5994 5995 5996 5997 5998 5999 6000

x = 0

x = 325

x = 14

x = 4325

x = 57

(b)


(a) (b)

(c) (d)

(e)



xy

z



4 Conclusions




Acknowledgments



References






























































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










707580859095

100105110115120125130

Pow

er ra

tio (d

B)

Frequency (THz)585 588 591 594 597 600 603 606 609 612 615

x = 0

x = 325

x = 14

x = 4325

x = 57

(a)Po

wer

ratio

(dB)

Frequency (THz)

70

80

90

100

110

120

130

5994 5995 5996 5997 5998 5999 6000

x = 0

x = 325

x = 14

x = 4325

x = 57

(b)


(a) (b)

(c) (d)

(e)



xy

z



4 Conclusions




Acknowledgments



References






























































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










xy

z



4 Conclusions




Acknowledgments



References






























































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation






















































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation

















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation









Documents

Research Article Designs and Performance Characteristics ...downloads.hindawi.com/journals/ijap/2015/345137.pdfat optical frequencies can exhibit a surface plasmonic char-acter. Nanostructures