Nanjing University CEAS D ielectric S uperlattice L aboratory Nat. Lab. Microstructures Dr. Tao Li [email protected]@nju.edu.cn vector near-field Plasmonic

Nanjing University CEAS

Dielectric Superlattice Laboratory

Nat. Lab. Microstructures Dr. Tao Li [email protected]

Tao Li（李涛）[email protected]

National Laboratory of Solid State Microstructures, College of Engineering and Applied Sciences

Nanjing University

KITPC, Beijing, 2015-10




Introduction

Plasmonic switch by composite interference

Plasmonic simulator for condensed matter physics

Conclusion




Surface Plasmon Polariton (SPP)

Sub-wavelength Field enhancement

Vectorial configuration of SPP field




Polarization converter Polarized active display Near-field interference

Metasufaces and Berry phaseChiral SPP in nanowire







Michelson interference

Unidirectional excitation of SPP

Science 340, 328 (2013)

Quantum interference and

quantum walkPRL 108, 023601 (2012)

Far field to near field

Classical to quantum




Plasmonic nanowire systemProf. Xu HX group,Nat. Comm. 2, 387 (2011)

Slot SPP waveguideProf. Gong QH group,Nano Lett. 12, 5784 (2012)




Degiorgio relation, δL+δR=π unidirectional beam,In symmetric system ， δL=δR=π/2

With a phase difference of π/2，Beam will be selectively routed to either right or left “switch”!

透反干涉T-R interference

Appl. Phys. Lett. 81, 1762 (2002)




For external modulation




Port I

Port II

III

IV

input

output

An ~80% interference depth is achieved

25 micro




6 micro

Switch between two outputs




Anti-synchronous

Shift! Why?




23 3 3 1 2 1 2| | , ( ) (1 )( )t r t tI E E E E E E

24 4 4 2 1 1 2| | , ( ) (1 )( )t r t tI E E E E E E

T-R 干涉 Field superposition

1 0 1 0cos( ), cos( )2t rE E t E E t

2 0 2 0cos( ), cos( )2t rE E t E E t

How to verify it?

Synchronous interference

Remove the BS to eliminate T-R part

No interference!?




Synchronousinterference!Reflection is

suppressed




Dependence to the strip width(simulation results)

In the case of non-reflection,how does interference take place?




Constructive interference

Ez

E//




w=2 um




1 1 1 1 1 1cos( ), cos( )2t rE t E t E r E t

2 2 2 2 2 2cos( ), cos( )2t rE t E t E r E t

3 4 1 2

1(1 )( )

2s sE E E E

23 3 3 1 2 3| | , t r sI E E E E E

24 4 4 2 1 4| | , t r sI E E E E E

T-R proportion

T-R interfer

Field superpositioninterfer







Compact SPP switch is achieved based on the

composite interference.

Two kinds of interferences are exploited in waveguide

system.

Vector field in slit-waveguide plays an important role.

Laser & Photonics Reviews 8, L47 (2014) (DOI: 10.1002/lpor.201300200)







Plasmonic waveguides Guiding the light

Waveguide array (lattice) Simulating quantum and condensed matter Physics

OE (2010)Nature Common (2013)Nature (2007)




Coupled mode equation in binary waveguide array

0 2 2 1 2 1

0 2 1 2 2 2

0

0

n n n

n n n

i E C E C Ez

i E C E C Ez

C

C

0( )K

C

0 1

1 0

i

i

A AeK

B Be

2 2 2 21 2 cos ( 1)K Dispersion equation:

Hamiltonian: 1 3

1( 1)

1waH

1C

C

1WAH

22

1 32D

mc cpH cp mc

cp mc

Dirac Hamiltonian: 1DH cp

massless

m=0




Non-dispersive splitting of optical wave




APL 103,141101(2013) PRL 109,023602(2012)

OE 35,11 (2010)

w

hg

Vector field




parameters ：lambda=633nm width=60nm height=120nm gap1=67nm gap2=146nm kappa=0.0177/-0.01775




60 nm

100 nmkappa=0.02515/-0.02545

kappa=0.0177/-0.01775




soliton

Topological soliton:lower energy (< bulk mode)fractional chargerobust against disorder

polyethylene chain

SSH model




strong Coupling

Weak Coupling

S0

S1

S2

kink

anti-kink

strong coupled defect

weak coupled defect

defectless

Coupled waveguide system:bonds coupling strength




Plasmonic counterpart

C1=0.188 , C2= 0.0332

Width=300nm

Top viewInput Simulation

Output

Coupling coefficient




Experiment Results

S0 S1 S2?




Theory analysisNotes:Excitation: Wave Packet Number: 79 Structure: S0, S1, S2

, 1 1 , 1 1( ) ( ) ( ) ( ) 0n n n n n n n ni a z C a z C a zz

S0 S1 S2




eigenvalue

eigenvector

Band structure and zero mode




Gaussians1 Gaussians2

As With the S1, S2 Also Processes the Topological Properties.

realistic excitation




Excitation ConditionsEigen mode Amplitude Resultant

Mode Symmetry

Eigen State↓

Amplitude Profile↓

Resultant Mode

S1

S2




S1 S2




Eigen mode Amplitude Amplitude with lossRobustness

S1Introduce randomness in coupling strengths C1 and C2

S2




S2

topological property ↔ robust against disorder

Laser & Photonics Reviews 9, 392 (2015) (DOI 10.1002/lpor.201400462)




Alternative coupling coefficients are modeled in the plasmonic ridge waveguide arrays, demonstrating the linear dispersion of massless Dirac Fermion.

SSH model is simulated in PWA system with an in-depth understanding of the topological interface state, and the influence of the excitation condition.




Vector field of SPP plays an important role in wave guiding




Grants: NSFC, 973 Project

http://dsl.nju.edu.cn/litao

Thank you!Thank you!

Yulin Wang, Qingqing Cheng, Beibei Xu, S.N. Zhu

Documents

Nanjing University CEAS D ielectric S uperlattice L aboratory Nat. Lab. Microstructures Dr. Tao Li [email protected]@nju.edu.cn vector near-field Plasmonic