negative index/refraction & fabrication + application

Negative Index/Refraction &

Fabrication + Application

EE235 2nd presentation

May 4th, 2009

Jun Rho

Cloaking & Invisible Man

Refraction & Snell’s law

1 1 2

2 2 1

sin

sin

v n

v n

1 2

1

sinc

n

n

Snell’s law

Total Internal Reflection

metals , ionic crystals

most dielectrics

no natural materials

negative materials

1 2 1 1 2 2 1 2 2 1

1 2

1 2

( ) ( )n n in i

where

i

i

Refractive Index

1

2

S k

RHM

LHM

1

2S k

RHM

RHM |

n

n|p

n

n

sin

sin

1

2

1

2

2

1

Snell’s Law

(p = -1 for LHM)

n1

n2 n2

n1 “Practical Applications” SuperLens HyperLens Cloaking

Negative Index Metamaterials

Superlens: Principle

X. Zhang et al, Vol. 308, pp 435-441, Nature Materials, 2008

Diffraction limit w/o superlens

Diffraction limit w superlens

~2

~5 6

Superlens: Experiment

N. Fang et al, Vol. 308, pp1534-5376, Science, 2005

Resolution achieved about 60-90nm

At wavelength = 365nm

Superlens: Fabrication

N. Fang et al, Vol. 308, pp1534-5376, Science, 2005

1. Cr deposition on a quartz substrate

2. Focused Ion Beam (FIB) patterning

3. Planarization

4. PMMA spacer layer deposition

5. Ag layer deposition

6. Near field photolithography

Images after hyperlens

Diffraction limit w/o hyperlens

22 pairs (R1: 400nm, R2: 1940nm)

-1500 -1000 -500 0 500 1000 15000

0.02

0.04

0.06

d (nm)

130nm

140nm150nm

160nm

0.04

|H|

0

0.02

45pairs 10nmAg/10nm Ta2O5(R1:100nm,R2:1000nm)

Object: 50nm separation, 20nm opening

Wavelength: 405nm

Hyperlens: Principle

Diffraction limit w/ hyperlens

At wavelength = 365nm

1.22 1.22 365155

2 2 1.44

nmnm

NA

1.22 1.22 365120

1.5 2.5

nmnm

NA M

Theoretically, diffraction limit is overcame. (120m < 150nm)

Experimental resolution limit?

Hyperlens: Experiment

130nmJ. Liu et all, Vol. 315, p 1686, Science, 2007

Hyperlens: Fabrication

1. Cr deposition on the quartz surface

2. Focused Ion Beam (FIB) patterning.

3. HF (BOE) wet etching

4. Remove mask layer

5. Multilayer deposition of Ag and Al2O3 by E-beam evaporator. Finally, the last Cr layer deposition is followed

Superlens & Hyperlens

X. Zhang et al, Vol. 308, pp 435-441, Nature Materials, 2008

Conventional lens Superlens

(Near field)

Superlens

(Far field)Hyperlens

Metamaterials: Principle & Fab.

RLC Circuit

Negative Permeability (µ) Negative Permittivity (ε) Negative Index (LHM)

Wire Grid Polarizer

k H

Ek H

E

S. Zhang, PRL, 2005S. Zhang, Opt. Exp., 2005

J. Valentine et al, Nature, 2008

Cloaking: Fab. & Experiment

J. Valentine et al, pp 1-5, Nature, 2008

Superlens More applications

Hyperlens Overcoming diffraction limit in visible wavelength Application to Bio-Engineering

Cloaking Bulk-metamaterials characteristics Manufacturing Issues

Future steps

Questions?