Peidong Yang

Department of Chemistry, University of California, Berkeley

Materials Science Division, Lawrence Berkeley National Laboratory

OneOne--Dimensional Nanostructures as Dimensional Nanostructures as Subwavelength Subwavelength

Optical Elements for Photonics IntegrationOptical Elements for Photonics Integration

Pushing the Size Limits of PhotonicsPushing the Size Limits of Photonics

S.Y. Lin et.al. Science 282, 274 (1998).

A. Birner et. al. Adv. Mat. 13, 377 (2001). V.L. Almeida et. al. Nature 431, 1081 (2004).R. Quidant et. al. Phys. Rev. B 69, 81402R (2004).

• Controlling the flow of light in small volumes – optical memory, logic, switching, etc.

Photonic Crystals (>1 μm) Slab/Slot Waveguides (<1 μm) Plasmonics (< 100 nm)

J.C. Krenn et. al. Phil. Trans. R. Soc. Lond. A 362, 739 (2004)Barnes et. al. Nature 424, 824 (2003).

K. Djordjev et. al. IEEE Phot. Technol. Lett., 14, 828 (2002).K.J. Vahala Nature (Insight Review), 424, 839 (2003). M. Paniccia et. al. Topics Appl. Phys., 94, 51 (2004).

OnOn--Chip Photonic IntegrationChip Photonic Integration

SOI fabrication approach

Heterogeneous Integration approachHeterogeneous Integration approach

H. Yan et al. Adv. Func. Mater. 12, 323,2002T. Kuykendall, P. Pauzauskie, et al. Nano. Lett. 3, 1063, 2003.

Single Crystalline, Single Domain, Single Crystalline, Single Domain, FacettingFacetting

VaporVapor--LiquidLiquid--Solid EpitaxySolid Epitaxy

Si Nanowire ArraysSi Nanowire Arrays

ZnO Nanowire ArraysZnO Nanowire Arrays

GaN Nanowire ArraysGaN Nanowire Arrays

P. Yang, Adv. Mater. 15, 353, 2003.Y. Wu et al. Chemistry, Euro. J. 8, 1260, 2002

M. Law et al. Annu. Rev. Mater. Sci. . 34, 83, 2004

Growth Direction ControlGrowth Direction Control

γ-LiAlO2 (100)< 1 1 0 > Alignment: GaN< 1 1 0 > Alignment: GaN

T. Kuykendall, P. Pauzauskie et al. Nature Mater. 3, 528,2004

< 0 0 1 >< 0 0 1 > Alignment: GaNAlignment: GaNSiC or MgO (111)SiC or MgO (111)

Superlattice

Interface within NanowiresInterface within Nanowires

Core-Sheath

Y. Wu et al.Nanolett, 2, 83, 2002. J. Goldberger et al. Nature, 422, 599, 2003 .

H. Choi et al. J. Phys. Chem. B 107, 8721, 2003.

Nanotube

M. Huang et al. Science, 292, 1897, 2001.

Semiconductor Semiconductor Nanowire MicrocavitiesNanowire Microcavities

Lasing Single ZnO NanowireLasing Single ZnO Nanowire

350 360 370 380 390 400 410 420

Wavelength (nm) J.C. Johnson et al. J. Phys. Chem B 105, 11387 (2001).

J. C. Johnson et al. J. Phys. Chem. B, 107, 8816, 2003.

H. Yan et al. Adv. Mater. 2004

)(2

2

λλ

λλ

ddnnL −

=Δ

GaN Nanowire NanolaserGaN Nanowire Nanolaser

Nature Materials 1, 101,2002

)(2

2

λλ

λλ

ddnnL −

=Δ

• Evidence for coherent laser pulses (GaN and ZnO)

Complex farComplex far--field emission patternfield emission pattern

Nanowire microcavity/laser

Highly Facetting/Single Crystalline

Lower limit λ/2n: r > 60 nm

Gth: 400 – 3000 cm-1

High-Q: 500-1500

Lower lasing threshold: ~ 70 nJ/cm2 (sub-ps pulses)

J. Phys. Chem. B, 107, 8816, 2003

Theoretical Simulation: Nanowire Lasers

C. Ning et al. APL, 83, 1237, 2003

th2e VCQ,Lre

Qn ⋅=×π×

=DS2

G

VLC

dVdI

⋅⎟⎠⎞

⎜⎝⎛⋅μ=

~ 50-200 cm2/V.s3181031 −×− cm

GaN Nanowire Transistor: nGaN Nanowire Transistor: n--typetype

Nano. Lett. 3, 1063, 2003.

pp--SOI/ nSOI/ n--GaN Nanowire Matrix LEDGaN Nanowire Matrix LED

H. Yan, J. Goldberger, Unpublished Results

pp--SOI/ nSOI/ n--GaN Nanowire Matrix LEDGaN Nanowire Matrix LED

H. Yan, J. Goldberger, Unpublished Results

Addressable UV LED ArrayAddressable UV LED Array

0.00E+00

5.00E-06

1.00E-05

1.50E-05

2.00E-05

2.50E-05

3.00E-05

3.50E-05

4.00E-05

4.50E-05

5.00E-05

0 2 4 6 8 10 120

20000

40000

60000

300 400 500 600 700 800Wavelength (nm)

Inte

nsity

(a.u

.)

Electroluminescence

Photoluminescence

Subwavelength oxide Nanoribbon Waveguides and Optical Elements

500 nm

Dimensions: Length > 1.5 mm Width 200 – 500 nm Thickness 100 – 300 nm

Aspect ratios > 1000

1 μm

1 μm

1 μm

1 μm

1 μm

Low-Loss Optical Waveguiding

excite

collect50 μm 350 400 450 500 550 600 650 700 750

5 K

300 K

Inte

nsity

(a.u

.)Wavelength (nm)

460 480 500

Inte

nsity

(a.u

.)

Wavelength (nm)

Propagation losses: 1 – 8 db/mm(NSOM)

400 500 600 700 800

Inte

nsity

(a.u

.)

Wavelength (nm)

22.5 kW/cm2

18.3 kW/cm2

11.8 kW/cm2

7.1 kW/cm2

4.7 kW/cm2

2.3 kW/cm2

0.4 kW/cm2

Dimensions: 715 μm x 350 nm x 245 nm

50 μm

500 nm

M. Law and D.J. Sirbuly et al. Science 305, 1269 (2004).

Non-Resonant Waveguiding

Cavity Manipulation

100 μm 25 μm200 nm

10 μm

ZnO nanowire

W tip

Manipulation size limits:

Wires: < 3 μm length< 50 nm dia.

Particles < 50 nm dia.

Used to cut, flip, bend, Used to cut, flip, bend, rotate, position, etc.rotate, position, etc.

3 μm 5 μm 1 μm

Shape Manipulation

300 400 500 600 700 800

PL SnO2

WG SnO2

WG ZnO

PL ZnO

Inte

nsity

(a.u

.)

Wavelength (nm)

Optical Optical HeterojunctionsHeterojunctions: : Evanescent wave coupling

1 μm

ZnO

SnO2

25 μm

Pump

Junction

Collect

The nanoribbon imprints its mode spectrum on the ZnO PL.

Subwavelength Optical Junctions and NetworksSubwavelength Optical Junctions and Networks

~ 50% of light energy couples through junction –evanescent waves

1

2

3

4

25 μm

1 2 & 3 1 & 42

CrossCross--Bar Assembly Bar Assembly –– Coupling Scattered LightCoupling Scattered Light

25 μm

200 nm

1

2

3

4

5

6

7

Pump

Intensity Variations: 1 >> 6 > 4 ≈ 7 > 3 > 5 >2

300 400 500 600 700 800

580 nm

527 nm

514 nm

492 nm

465 nm

Inte

nsity

(a.u

.)

Wavelength (nm)

300 400 500 600 700 800

Inte

nsity

(a.u

.)

Wavelength (nm)

Increasing pump –probe distance

PL

Size Effect on Waveguiding

Short-pass filters:580 nm 375 x 140 nm (0.052 μm2)

527 nm 250 x 225 nm (0.056 μm2)

514 nm 350 x 115 nm (0.040 μm2)

492 nm 280 x 120 nm (0.034 μm2)

465 nm 310 x 100 nm (0.03 μm2)

2/122 )( clco nndV −=λπ

2/122 )(405.2 −− −= clcooffcut nnd λ

π

405.20 <<VSingle-mode operation:

V-parameter:

λcut-off Dimensions

Filtering White Light (MultiFiltering White Light (Multi--Channel)Channel)

210 x 135 nmλcut-off = 478 nm

260 x 175 nmλcut-off = 502 nm

350 x 140 nmλcut-off = 543 nm

single mode cut-off (cylindrical step-index fiber) Diameter (nm)543 nm 274 nm502 nm478 nm

253 nm241 nm

0.05896

Area (um2)

0.05027

0.045617

Exp. Area (um2)0.04900

0.04550

0.02835

Waveguiding Nanowire Laser Pulses Waveguiding Nanowire Laser Pulses -- GaNGaN

350 360 370 380 390 400

10

20

30

40

WG Lasing

GaN Lasing

WG PL

GaN PL

norm

aliz

ed in

tens

ity (a

.u.)

wavelength (nm)

GaN

SnO2

25 μm

ZnO

GaN

SnO2

350 360 370 380 390 400 410

Inte

nsity

(a.u

.)

Wavelength (nm)

ZnO

GaN

Dual Nanowire Laser InjectionDual Nanowire Laser Injection

Wave Mixing?

132213 ωωωωωω −=+=

Detect

50 μm

Waveguiding in Liquids Waveguiding in Liquids –– High Index NanowiresHigh Index Nanowires- Local bio-medicinal probe/spectroscopy (in vivo)- Micro/nanofluidics, PDT, chemical photo-release,

integrated bio-chip, etc.

100 μm

Glycoln = 1.45

Watern = 1.33

25 μm

Excite 442 nm

10 μm

540 μm x 240 nm x 260 nm

• Inject resonant light to induce local fluorescence at the end or along the length of the ribbon.

Local Fluorescence Scheme

• Probe direct or back-guided fluorescence.

3 pL

1 mM R6G

D.J. Sirbuly and M. Law et al. PNAS (2005).

Nanowire Evanescent Subwavelength SpectrometryNanowire Evanescent Subwavelength Spectrometry

400 500 600 700 800

535 nm

Inte

nsity

(a.u

.)

Wavelength (nm)

Dry Ribbon Pure Solvent 50 μM R6G 1.6 mM R6G

Inject broad light source and probe waveguided photons.

Utilize evanescent field to detect molecules. 50 μm

1.6 mM R6G

V ~ 1 pL

430 μm x 240 nm x 260 nm

Detect

Generate PL

sub-picoliter probe volumes

path lengths of 1-50 microns

detection of 103 molecules is achievable

Local Absorption Scheme

Nanowire Evanescent Subwavelength SpectrometryNanowire Evanescent Subwavelength Spectrometry

Semiconductor Nanowires as Semiconductor Nanowires as Subwavelength Photonics IntegrationSubwavelength Photonics Integration

OnOn--Chip Heterogeneous Photonic IntegrationChip Heterogeneous Photonic IntegrationPushing the Size Limits of PhotonicsPushing the Size Limits of Photonics

Precise 1-dimensional nanostructure synthesis and assemblySelf-Organized Optical Cavity

Nanowire based optical cavity, UV coherent light sourcesFrom Fabry-Perot cavity to ring laserFrom optical pumping to light emitting diodes, and laser diodesSubwavelength optical waveguidesOptical waveguiding in solution, interface with microfluidicsSubwavelength optical spectroscopy (absorption, PL…)

Acknowledgements Acknowledgements

Dr. Michael HuangDr. Yiying Wu

Dr. Heonjin ChoiHaoquan YanDr. Justin Johnson (Saykally Group)

Dr. Don SirbulyPeter PauzauskieMatt LawJosh GoldbergerTev Kuykendall

Dr. Alex Maslov (NASA Ames)Collaborators Prof. Richard Saykally (UCB)Dr. Cun-Zheng Ning (NASA Ames)

FundingDOE, NSF, DARPA

Beckman Foundation