B.Dagens, Journées thématiques GdR Ondes, Grenoble, 17 et 18 janvier 2013 1 Plasmonique intégrée pour circuits photoniques à haute densité Mickaël Février,

B.Dagens, Journées thématiques GdR Ondes, Grenoble, 17 et 18 janvier 2013 1

Plasmonique intégrée pour circuits photoniques à haute densité

Mickaël Février, Lukas Halagacka, Matthias Grangier, Yida Wen, Philippe Gogol, Abdelhanin Aassime, David Bouville, Navy Yam, Robert Megy, Béatrice Dagens

Coll: LNIO (UTT) et CEA-LETI


Integrated plasmonic : why ?

µfluidic channel

Optical source Optical detectorSensor area

Integrated bioplasmonic sensor

Specific functions, miniaturized functionsEfficient excitationSpatial separation of « active function » and excitation/detection system

Complex circuits Efficient devices

Optical interconnects, optical circuitry, nanoantennasIsolators, circulators

Isolator

Circulator

Principle: enhanced properties thanks to nanostructuration and guiding effects


Outline

• Integrated plasmonic : why ?

• State of the art

• Localized surface plasmon chains

• SOI - LSP chain interfacing

• From long to short plasmonic chains

• Back to waveguide coupling

• Chain mode harmonics

• Application to biosensing

Gold nanoparticles

SOI waveguide


State of the art : interfacing SOI and plasmonic waveguide

• reflexionslosses• Coupling efficiency between 15%

and 30%

Chen et al, Opt. Lett., 31, 2133, 2006

Tian et al, APL, 95, 013504, 2009

Briggs et al, Nano. Lett., 10, 4851, 2010


• State of the art• Localized

surface plasmon chains

• SOI- LSP chain interfacing





Butt-joint coupling


State of the art : interfacing SOI and plasmonic waveguide

Sederberg et al, APL 96, 121101, 2010

Delacour et al, Nano. Lett., 10, 2922, 2010• Reduced reflections• Coupling efficiency: 60% to 70%

Evanescent coupling










State of the art : localized surface plasmons nanoparticles deposited on a waveguide

Quidant et al, PRB 69, 085407 (2004)

• successive metallic NP: correlated excitation through underlying dielectric waveguide (like in Bragg grating)

• but no direct coupling between NP

Bragg grating made of metallic nanoparticles










Localized surface plasmon (LSP) chains

Simsek, Optics Express , 18, 1722, 2010

Plasmonic resonance generated by an

electromagnetic excitation in a metallic nanoparticle

(subwavelength dimension)

Excited particle= oscillating dipole

Near field excitation of the nearest particle:

electromagnetic energy propagation

Plasmonic resonance controlled by the

size, shape, position of nanoparticles










Ellipsoidal MNP polarisability

Response of MNP to electromagnetic field depends on polarisability a (for isolated MNP or for MNP assembly)

Ep d

04

Polarisability a includes static response (dielectric cstt, shape of the ellipsoid)

But also radiative effects (dimensions of the NP with respect to wavelength, retardation effects, …)

)(33,0

dmud

dmzyxu Laaa

1

2

2

3

3

,0 3

21

vavi

uuu

with

0 2/1

,,

22 )()(2

zyxmmu

zyxu

qaqa

dqaaaL

zyxu aaaa

zyxu

,,

,,

x

zy

(ellipse semi-axis)









ed

em


Ellipsoidal MNP polarisability

polarisability a is sensitive to MNP environment, shape and dimensions

ay= 40110 nm

Po

lari

sab

ilit

y (i

mag

par

t)

ax=40nm, az=15nm









x

zy

ay

ed

em

Eext


(LSP) chains design

Weber et al, PRB, 70, 125429, 2004Koenderink et al, PRB, 74,033405, 2006

3 2 330

/( ) 14

ˆ ˆ3( )1 ˆ ˆ( )² m mm mN i n md c

m n

extn n

i n m dc n m d c n m d

e

r p r p p r p rp E

Model “Couple Dipole Approximation” (in homogeneous medium)

• each nanoparticle = one point, with polarisability a

• radiative losses, NP geometry, gold index (Drude model)

• long and short distance interaction

P: dipolar moment

E: external excitation

α: polarisability

ω: pulsation

d: interparticle distance

Contribution of other MNP 1/r, 1/r² and 1/r3 interactions

Gives the excitation profile along the finite chain (|pn|²~dissipated ohmic power)

Defines collective oscillation of chain dipoles of the infinite or finite chain : eigenmodes (En

(ext)=0) in homogeneous medium: dispersion curve










(LSP) chains modelling (in homogeneous medium)

Dispersion curves of the infinite chain :

Dispersion curves of the finite chain :









20 MNP chain in homogeneous media


Designed and realized device

• Design: analytical and then FDTD models• Telecom wavelength, TE mode: ellipsoidal shape• E-beam lithography (alignment) + lift-off process• 30 nm thick gold nanorods

2 ax

2 ay

2 ay~ 220 nm

2 ax~ 80 nm

Localized surface plasmon excitation ? Chain = waveguide ?










20 MNP: transmission spectrum

• Resonance transmission minimum• « noise »: FP modes• FDTD simulation (experimentally fitted Drude model): 5dB extra losses









Transmission setup(IEF)

Chain excitation ? Coupling mechanisms ?


Near-field : traNSNOM(LNIO, UTT)










M. Fevrier et al. Nano Lett. 12, 1032, 2012

(a)(b) (c)

(a)

(b)

(c)










Dispersion curves

FDTD calculation extracted dispersion curve of the 20 MNP chain on SOI

Coupled modes (anticrossing) chain=waveguide









Dispersion curves of a chain in homogeneous medium and of the SOI waveguide


From 5 to 50 MNP chain

10 MNP

20 MNP 50 MNP

5 MNP

- transmission: similar spectral shape, wider for longer chains- much lower transmission at 5MNP: cavity effect










From 5 to 50 MNP chain

l=1475 nm

5MNP, 1325 nm

20MNP, 1475 nm 50MNP, 1465 nm

10MNP, 1321 nm

Intensity profiles at transmission minimum

- 20 and 50 MNP: clear waveguide coupling- 10 MNP: intermediate case- 10 to 50 MNP: same coupling length

- 5 MNP: too short for re-coupling ; total energy transfer into the fourth MNP (<500nm)










Dipole excitation: experimental validation

5MNP, 1325 nm

20MNP, 1475 nm

Very short chains (5MNP) sufficient to implement plasmonic functions










Record coupling length

2LcLc ≈ 560 nmκ ≈ 2805 mm-1

Waveguides Coupling length (Lc)

SOI/nanoparticle chain ≈ 560 nm (measure, Fevrier et al. Nano Lett.)

SOI/delocalized plasmonic waveguide

≈ 1 µm (measure, Delacour et al. Nano Lett.)

2 dielectric waveguides ≈ 100 µm (theory, Sun et al. Optics Lett.)










LSP chain on Si3N4 waveguide

Waveguide coupling Longer coupling length in Si3N4 waveguide case









M. Février et al, submitted to JLT


Excitation near or far of the light line









Lc = λ/[2(neff antisym − neff sym)]


Strong interaction due to device geometry

Mode distortion, especially in dielectric waveguide



Excitation up to « non guided » mode

Low guiding in Si3N4

Antisymmetric supermode with index higher than material index











Excitation up to « non guided » mode

appears on transmission curve










Guiding based on resonances and near-field coupling

1rst Brillouin zone

chain

SOI

dkb

kb=2pd

d=150 nm

Spatial harmonics : - generated by chain periodicity - includes decreasing phase contribution- may be as intense as fundamental

component










Specific collective chain modes

FDTD

1rst et 2nd Brillouin zones

Strong excitation of spatial harmonics in chain waveguide

-

2,561,6

Heterodyne SNOM (LNIO, UTT)

-40 -30 -20 -10 0 10 20 30 40

NeffA. Appuzzo, accepted for publication in Nano Letters










Biochips : plasmonics waveguides

Silice Si02

SAM thiol/orSAM silane

/ SiO2or

Bio-plasmonics for molecular interaction with localized plasmons

Possible detection in transmission

Compatibility with further integration with “lab-on-chip” systems: thiols molecules grafting on gold; thiols can “capture” element to be detected

Plasmonics response strongly modified by the presence of these elements (molecules, ...)










Toward biosensing

Calculation: chain of 5 gold nanoparticles coated with dielectric material.

experiment

Mickaël Février, et al, « Integration of short gold nanoparticles chain on SOI waveguide toward compact integrated bio-sensors, » Optics Express Vol. 20, Iss. 16, pp. 17402–17409 (2012)


Conclusion and perspectives

• Integration of localized plasmon waveguide on SOI demonstrated, at telecom wavelength

• Several efficient excitation and propagation regimes identified• Very short chains (5MNP) sufficient to implement plasmonic functions• Similar behaviours with SiN guide (compatible with visible wavelength)

Short chain = reduced losses, compactness Plasmonic= energy concentration (non-linear functions, sensing, …) Toward magneto-plasmonic (Au/Co/Au)


Thanks for your attention

Documents

B.Dagens, Journées thématiques GdR Ondes, Grenoble, 17 et 18 janvier 2013 1 Plasmonique intégrée pour circuits photoniques à haute densité Mickaël Février,