Plasmonics, Metamaterials and Their Applications in Light Manipulations

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(ECE) Material Science Engineering (MSE) Center for Magnetic

1 Plasmonics, Metamaterials and Their Applications in Light Manipulations Zhaowei Liu Electrical & Computer Engineering (ECE) Material Science Engineering (MSE) Center for Magnetic Recording Research (CMRR) University of California, San Diego (UCSD)

2 Light Manipulation Nanoscale Nanolithography Energy harvesting Bioimaging & sensing LEDs and detectors High resolution High speed High sensitivity High efficiency Nanophotonics Plasmonics Nano-materials Light matter interactions

3 Optical Materials (a) (b) y 0, 0 Ag, Au 0, 0 Most materials Strong Anisotropic Media Negative Index Media 0, 0 Fe, Co 0, 0 x New materials properties provide new possibilities!

4 Optical Imaging Systems Telescope Eye Microscope 3D imaging system

5 Optical Microscope 1590 s 1900 s 1998

6 The Foundations of Optical Microscopy The light illumination The material -- glass The theoretical limit August Köhler ( ) Otto Schott ( ) Ernst Abbe ( ) The diffraction limit

7 What is Diffraction Limit image E( x, y, z) E0e ik x x e ik y y e ik z z object z Propagating waves θ x evanescent waves k n k k c z ( ) ( x y ) k x2 +k y2 <(nω/c) 2 k z is real propagating waves big features of the object k x 2 +k y2 >(nω/c) 2 k z is imaginary Amplitude exponentially decay evanescent waves small features of the object Evanescent waves are lost at the image plane Diffraction limited resolution

8 Methods to Improve Resolution x / nsin( ) Reduce working λ Light Increase n Air EUV X-ray Electron beam Ion beam Oil immersion ( ) Solid immersion (n=1.5~2)

$Perfect Lens Theory A slab of negative refractive index material (NRIM) can perform as a$ Pendry Imperial College n=1 n=-1 n=1 Object plane n=-1 Evanescent waves image plane Fresnel

Pendry Imperial College n=1 n=-1 n=1 Object plane n=-1 Evanescent waves image plane Fresnel

9 Perfect Lens Theory A slab of negative refractive index material (NRIM) can perform as a perfect lens air air n 0 =1 n = 1 n 0 =1 0 Propagating waves Snell s law sin sin 0 1 John Pendry Imperial College n=1 n=-1 n=1 Object plane n=-1 Evanescent waves image plane Fresnel equation T p ( k, d) x t01t12 exp( ik d) r r exp( ik d) z z1 Phys. Rev. Lett. 85, (2000).

10 What are Metamaterials? A metamaterial (or meta material) is a material which gains its properties from its structure rather than directly from its composition. Nature Materials Metamaterials 1nm 10 nm -100 m Unit: atoms Unit: Meta atoms Artificial nanostructures

11 Metamaterials at MW NIM, UCSD, Science, 2001 Boeing, bulk NIMs High n, KAIST, Nature, 2011

Metamaterials: from MW to Optical Optical Metamaterials More bulky and less lossy 0 0 xx 0 yy 0 0 0 zz FOM: order of magnitude

12 Metamaterials: from MW to Optical Optical Metamaterials More bulky and less lossy 0 0 xx 0 yy zz FOM: order of magnitude improvement Fabrication: order of magnitude easier Practical Optical Metamaterials: Plasmonic metamaterials μ=1 Science, Dec. 2010

Superlens Imaging Using Metal 40nm Ag film @3.

13 Superlens Imaging Using Metal 40nm Ag Simulated resolution <80nm J. B. Pendry, Phys. Rev. Lett, 2000

Permittivity New Imaging Paradigm: Plasmon Optics Surface plasmons (SPs)

dielectric k z z E z ~e - k z z -20-30 -40 2 + + + + + + 1 H y metal K x E

8 1 Wavelength (um) Main features of SPs k Shorter wavelength (comparing

14 Permittivity New Imaging Paradigm: Plasmon Optics Surface plasmons (SPs) are collective free electron oscillations at a conductor surface Ag 0-10 E dielectric k z z E z ~e - k z z H y metal K x E z Wavelength (um) Main features of SPs k Shorter wavelength (comparing with excitation light) Bound to the surface Propagation along the surface Evanescent enhancement H. Raether, Surface Plasmons, (1988).

15 Evanescent Enhancement by Metal Film RATR setup (a) E E Schematics silver Evanescent field enhancement increase with increasing silver film thickness. Loss play an important role when the film is thicker than 50nm Z. Liu, et al, Appl. Phys. Lett. 83, 5184 (2003)

Ag superlens Image without Ag superlens The

16 First Optical Superlens Demonstration N. Fang, et al. Science, 2005 SEM of an object superlens Image with Ag superlens Image without Ag superlens The super-resolution image only exist at the near-field of the lens

Liu, et al, Nano. Lett. 7, 403 (2007) S.

17 Far-field Superlens Far-field Superlens: Image with super resolution at far field (a) Evanescent Propagating Evanescent -k Λ -nk 0 0 nk 0 k Λ k x (b) -k Λ -nk 0 0 nk 0 k Λ k x λ=405nm (c) a b c Ag d (e) (d) (f) 100nm Z. Liu, et al, Nano. Lett. 7, 403 (2007) S. Durant, Z. et Liu, al, JOSAB, et al, Opt. 2006, Express Z. Liu, 15, et al, 6947 Nano (2007) Lett S. Durant, Z. Liu, et al, J. Opt. Soc. Am. B. 23, 2383, (2006) Y. Xiong, Z. Liu, et al, Nano. Lett. 7, 3360 (2007)

18 Optical Hyperlens Evanescent Propagating Evanescent k x -k 0 0 k 0 Compress the wavevector from evanescent to propagating

19 Principle of Optical Hyperlens Support wave propagation with very high wavevector k 2 x y k 2 y x k 2 0 0, 0 x y x 0, 0 y k y k y x k 0 x k 0 y k 0 k x k x n 2.4 No naturally existing materials

20 An Example Artificial Metamaterials with extraordinary material properties Metal: Dielectrics: - ε + ε Metal/dielectrics multilayer y x Effective Media: d d x m m d d ( d d ) /( d d ) y m d m d d m m d x 0, 0 y

21 Optical Hyperlens Compress the wavevector by geometry d m d d k r k 0, 0 k r 2 2 r 2 k0 Hyperbolic dispersion r Rk Constant propagating k θ There is no cut-off for k θ k θ gets compressed with increasing R k θ finally can be propagating (Engheta, PRB, 2006 and Narimanov, Opt. Express, 2006)

$a sub-diffraction limited object into a$

22 Optical Hyperlens Anisotropic metamaterial: Metal/dielectrics multilayer R2 R1 A Hyperlens can magnify a sub-diffraction limited object into a diffraction limited image

23 Experimental Demonstration Z. Liu, et al. Science, 315, 1686 (2007)

24 Sample Fabrication 1. Cr coating 2. FIB mask fab. 3. Wet etching Quartz 4. Remove Cr 5. Ag/Al 2 O 3 deposition -- Hyperlens 6. Cr deposition -- Object 7. FIB object fab H. Lee, and Z. Liu, et al. Opt. Express, 15, (2007)

25 Experimental Demonstration (a) (b) (c) 1μm SEM Image 130nm λ=365nm λ=410nm Science 315, 1686 (2007), Nature Communications 1, 143 (2010)

26 Flat Hyperlens Y. Xiong, et al. Appl. Phys. Lett. 94, (2009) A. V. Kildishev and V. M. Shalaev, Opt. Lett. 33, 43 (2008) S. Han, et al. Nano Lett. 8, 4243 (2008)

27 High Speed High Resolution Bio-imaging Neurontransmitter Dynamics Cell membrane dynamics

28 Nanowires Based Bulky Plasmonic Metamaterials -Positive Phase Index, Broadband and Low Loss Indefinite medium sample Yao, Liu et., al., Science 2008 Nanowire array y (H) x y z x z Collaboration with Prof. Angelica Stacy, Berkeley Top view Side view

$Refraction Angle (degree) Experimental Results Negative Refraction n TE =2.$ 0 λ=660nm TE θ=-30 λ=780nm TE θ=-30 10 λ=780nm TM mode TE mode TM θ=30 TM θ=30

29 Refraction Angle (degree) Experimental Results Negative Refraction n TE =2.2 n TM =-4.0 λ=660nm TE θ=-30 λ=780nm TE θ= λ=780nm TM mode TE mode TM θ=30 TM θ=30 0 θ=0 θ= Lateral position (μm) Lateral position (μm) Incident Angle (degree) Yao, et., al., Science 321, 930, (2008)

$Wavelength (nm) Wavelength (nm) Negative Refraction Flat Lens @$ 5 B 400 0 2 4 6 8 wave vector / (k // (m -1 )) x 10 7 300

5 A No focal length can be defined Flat metamaterial lens

30 Wavelength (nm) Wavelength (nm) Negative Refraction Flat VIS 300 (a) nm Full-wave Simulation B wave vector / (k // (m -1 )) x Effective Slab 350 (c) x 10 7 Collaboration with wave vector Prof. / (k // Yuh-Lin (m -1 )) Wang, Academia Sinica A No focal length can be defined Flat metamaterial lens Material supports super resolution, but impossible to achieve in the flat geometry J. Yao, et al. Opt. Express, 17, (2009)

31 A Recent Advance?

32 New Optical Phenomena

33 Invisibility & Illusion Harry Potter

$Plane wave focusing (OFT) Imaging x / NA 1 s1 s2 f 2 Resolution: diffraction limited 1 1 1 Imaging Equation$

34 Conventional Optical Lens Lens: the most fundamental transformation element s 1 s 2 f object real image f f Plane wave focusing (OFT) Imaging x / NA 1 s1 s2 f 2 Resolution: diffraction limited Imaging Equation

35 Superlenses air n 0 =1 0 n = 1 air n 0 =1 Propagating waves Coordination Transformation Object plane n=-1 image plane Evanescent waves Perfect lens concept J. B. Pendry, PRL 85, 3966 (2000) Near-field superlens N. Fang et al., Science 308, 534 (2005) Hyperlens Z. Liu et al., Science 315, 1686 (2007); Z. Jacob et al., Opt. Express 14, 8247 (2006) Super resolution - high k-vector included in image. No plane wave focusing - no Fourier transform (FT)

To Make a Lens by Plasmonic Metamaterials To develop three phase compensation mechanisms in the Metalens (a) (b) (c) Air Air Air Air Metal Metamaterial

$super resolution is enabled by the metamaterial properties. The hyperbolic metalens (i.e. the plasmonic metamaterial has hyperbolic dispersion) experiences negative refraction at air/metamaterial interface C.$

36 To Make a Lens by Plasmonic Metamaterials To develop three phase compensation mechanisms in the Metalens (a) (b) (c) Air Air Air Air Metal Metamaterial Metamaterial shaping Metamaterial Plasmonic waveguide array to introduce phase modulation Inhomogeneous Metamaterial Gradient index metamaterial The super resolution is enabled by the metamaterial properties. The hyperbolic metalens (i.e. the plasmonic metamaterial has hyperbolic dispersion) experiences negative refraction at air/metamaterial interface C. Ma, and Z. Liu, Appl. Phys. Lett. 96, (2010) C. Ma, and Z. Liu, Opt. Express, 18, 4838, (2010)

Metamaterial Immersion Lenses (MIL) The most fundamental property of a lens

Air Hyperbolic MIL Plane wave (i) Air (ii) θ Metamaterial k z kx Elliptic

37 Metamaterial Immersion Lenses (MIL) The most fundamental property of a lens plane wave focusing (Fourier transform) Metamaterial + interface shaping (a) Air Hyperbolic MIL Plane wave (i) Air (ii) θ Metamaterial k z kx Elliptic Dispersive Metamaterial (ε x > 0, ε z > 0) 7.2 um ~ λ/9 6.7 um 3.0 um Δx = 310 nm C. Ma and Z. Liu, Opt. Express 18, 4838 (2010) (iii) x Air z Hyperbolic Dispersive (ε x > 0, ε z < 0) Metamaterial 3 um ~ λ/ um 0.77 um (iv) Δx = -120 nm θ

Metalenses To introduce precise phase modulation by introducing a

(iii) Metal (iv) FWHM = 59 nm ~ λ/6 FWHM = 52 nm ~ λ/6 Hyperbolic

9 μm Metamaterial 3.6 μm 117 nm Metamaterial 2.8 μm 210 nm C. Ma and Z.

38 Metalenses To introduce precise phase modulation by introducing a plasmonic waveguide array (i) (ii) Elliptic Dispersive Metamaterial (iii) Metal (iv) FWHM = 59 nm ~ λ/6 FWHM = 52 nm ~ λ/6 Hyperbolic Dispersive Metamaterial Metamaterial (a) Air (b) (c) Air (d) 2.2 μm 1.9 μm Metamaterial 3.6 μm 117 nm Metamaterial 2.8 μm 210 nm C. Ma and Z. Liu, APL 96, (2010), C. Ma, and Z. Liu, J. Nanophotonics, 5, (2011)

B' ~λ/5 22 12 2-5 ε ε z ε x 0 (μm) 5 x 7.

39 GRIN Metalens x A O P 1 2 C A' O' z B Focus Converging region Diverging region B' ~λ/ ε ε z ε x 0 (μm) 5 x 7.2 μm Metamaterial 2.8 μm 1.4 Air 284 nm Metamaterial 165 nm C. Ma, M. Escobar, and Z. Liu, Phys. Rev. B 84, (2011)

40 An Intriguing Hyperbolic Metalens (a) (c) F m F d F m Janus God Air ' x ' 0, z 0 Metamaterial (c) (d) Janus Lens F d F d F m Air ' x ' 0, z 0 Metamaterial C. Ma, and Z. Liu, Opt. Express 20, 2581 (2012)

Conventional Lens Metalens (Comparison for imaging characteristics) For conventional optical lens Imaging equation Object Image Location Type Location Orientation Relative size > s o > 2f Real f< s i

41 Conventional Lens Metalens (Comparison for imaging characteristics) For conventional optical lens Imaging equation Object Image Location Type Location Orientation Relative size > s o > 2f Real f< s i < 2f Inverted Minified s o = 2f Real s i = 2f Inverted Same size f < s o < 2f Real > s i > 2f Inverted Magnified s o = f ± s o < f Virtual s i > s o Erect Magnified 1 s o 1 s i 1 f For Hyperbolic Metalens 3, 1205 (2012) Object Image Location Type Location Orientation Relative size > v d > 0 Real 0 < v m < f m Erect Minified > v m > 2f m Virtual 2f d < v d < f d Inverted Minified v m = 2f m Virtual v d = 2f d Inverted Same size f m < v m < 2f m Virtual - < v d < 2f d Inverted Magnified v m = f m ± v m < f m Real > v d > 0 Erect Magnified Subscription d and m means the location in either dielectrics or metamaterials ' ' ' ' 1 z / x z / x v v f d m ' ' 1/ vd ( z / x ) / vm 1/ fd m Metalens enables exotic imaging systems that previously thought impossible A review article in Nature Communications, 3, 1205 (2012)

42 Object in Air Real image always formed! a Object b Image Object Image Air F d F m Metamaterial Air F d F m ' ' ( x 0, z 0) Metamaterial Conventional optical lens f f

43 Compound kinoform plasmonic lenses Opt. Commun.291, 390 (2013)

44 Structured illumination Microscopy (SIM) Resolution improved twice in fluorescent microscopy without with Spatial Light Modulator (SLM) M. G. L. Gustafsson, J. Microsc. 198, 82 (1999) 44

45 Structured Illumination Microscopy Object Illumination Image (a) (b) (c) (a) (b) (c) k k Detection Illumination Image Info

46 SIM PSIM Light interference Surface plasmon wave interference (better resolution) ω Photon ω=ck metal 10μm ω 2 ω 1 Surface Plasmon 1μm λ=365nm λ=514nm k sp1 k sp2 kx Nano Lett. 2005, Nano Lett SIM PSIM k obs k light k sp

47 Resolution Issue Conventional OM x emi 2NA 1X Conventional SIM x emi 2NA 2NA emi / abs >2X emi Plasmonic SIM (PSIM) x >3X 2NA 2NA eff The NA eff is only determined by the plasmonic structure NOT the objective For instance, NA of the objective is 0.5 NA eff of the plasmonic structure can be 1.5 Current work (2): PSIM

Plasmonic Structured Illumination Microscopy mirror

Laser prism SIM PSIM NA lens glass metal object θ

resolution enhancement (50-100nm) Speed: >30

48 Plasmonic Structured Illumination Microscopy mirror lens lens DMD High speed light modulator OM lens Laser prism SIM PSIM NA lens glass metal object θ objective Plasmonic Structures CCD Resolution: >3X resolution enhancement (50-100nm) Speed: >30 frames/second (faster than real movie speed) Current work (2): PSIM

85 Resolution: ~80nm Enhancement factor: ~3.8 F.

49 PSIM: example design (1) PSIM excitation wavelengths: 442nm PSIM detection wavelength: 508nm Detection NA: 0.85 Resolution: ~80nm Enhancement factor: ~3.8 F. Wei, and Z. Liu, Nano. Lett. 10, 2531 (2010) Current work (2): PSIM

50 Super Resolution Lithography

51 Surface Plasmon Interference Nanolithography (SPIN) 3μm E x ~60nm E z E λ=365nm 10μm Metal: Al Working λ: 266nm Simulation λ=514nm Z. Liu, et al, Nano. Lett. 9, 462 (2009) Z. Liu, et al, Nano. Lett. 5, 957 (2005)

52 FSL for Lithography

53 For 2D Periodic Lithography (a) 2D transfer function for a 12 pairs of 35 nm Ag and 21 nm SiO 2 multilayer at a wavelength of 405 nm. (b) The simulated E field at the plane 3 nm after the multilayer.

54 Hyperlens for Lithography 54

55 Hyperlens for Lithography A simple design of flat hyperlens for lithography and imaging with half-pitch resolution down to 20 nm 55

56 Plasmonic Super Contrast Imaging Dark-filed Microscopy

57 Dark-Field Microscopy (a) (b) Can NOT be used for imaging

58 Plasmonic Dark-Field (PDF) Microscopy

59 Preliminary Imaging Results on PS Beads (a) Conventional dark field image Conventional dark field image (b) PDF image Plasmonic dark field image H. Hu, et al. Appl. Phys. Lett. 96, (2010)

60 OLED Based Plasmonic Dark Field Microscopy Opt. Lett. 2012

61 Experimental Results

62 LED Based PDF

63 Plasmonic Super Contrast Imaging Phase Contrast Microscopy

Phase Contrast Microscopy Current methods: Convert phase

features Differential Interference Contrast Microscope

64 Phase Contrast Microscopy Current methods: Convert phase information, via optical path differences, into intensity variation. Problem: Not practical for very thin samples or very fine features Differential Interference Contrast Microscope Phase Contrast Microscope Phase Contrast Microscopy Can the same be done with plasmonics? Simpler? Better?

65 Plasmonic Metamaterial Waveguide Nano. Lett. 10, 1 (2010), collbrated with O. G. Schmidt group at IFW Dresden, Germany

66 Plasmonic Metamaterial Waveguide Nano. Lett. 10, 1 (2010), collbrated with O. G. Schmidt group at IFW Dresden, Germany

67 Special Properties

68 Light Plasmonic Metamaterial Interactions Optical plasmonic metamaterials Quantum Efficiency (intensity) Plasmonic Enhancement Fluorescence molecules Semiconductor QW, WD Optical Pump Electrical Pump Life-time (speed) Fluorescence ~ns Plasmonics ~10-100fs

69 Plasmonic Enhanced PL Near field coupling between LED and SPs on metal film Surface structure convert SPs into free space photons Nature Materials (2004)

70 Plasmonic Enhancement APL, 2005; Nat. Mat. 2004; Adv. Mat. 2008; IEEE 2009 SP resonance Light emission peak w/o metal w/ Ag

71 Hyperbolic Metamaterial Enhanced PL = 2 ns z y x = 1.1 ns [Science 336, 205 (2012)] [APB 100,215 (2010)] Jacob, Shalaev, Menon, Noginov [OL 35,1863 (2010)]

72 Hyperbolic Metamaterials + Light Emitters

73 Continue

74 Structured Hyperbolic Metamaterials Couple non-radiative SPs to propagating photons!

75 Metamaterial Enhanced Fluorescence Manuscript submitted 20nm

76 Counts Experiment: Emission Speed Enhancement (a) (b) 270nm (c) 270nm 300nm 200nm glass 200nm glass 200nm glass R6G mixed in PMMA Ag Ag 80nm 80nm 80nm Al 2 O 3 Si Ag 30nm Al 2 O 3 30nm Ag 10nm Si 10nm (d) t=0.07ns t=0.4ns t=0.1ns To appear in Nature Nanotechnology Time (ns) t=3.8ns ~50X Enhancement AgSi Ag/Si ML stacks AgAO Ag/Al 2 ML O 3 stacks Ag Single SL Ag layer R6G in in methanol

77 Experiment: Brightness Enhancement To appear in Nature Nanotechnology

78 Major Other Research Topics Quantum plasmonics and Thermoelectronics Ultrafast LEDs and communications 3D real time brain imaging Nonlinear plasmonics

79 Summary Passive light propagation control super resolution microscopy super contrast microscopy plasmonic/metamaterial waveguides Active light emission control Plasmonic/metamaterial LEDs What nature can do??

80 Acknowledgements Group members: Dr. Changbao Ma (previous) Dr. Wenwei Zheng Dr. Bahar Khademhosseinieh Dr. Dominic Lepage Feifei Wei Dylan Lu Justin Park (previous) Lorenzo Ferrari Weiwei Wan (pre) Dae Yup Han Hao Shen Eric Huang Joseph Ponsetto Bryan Van Saders Qian Ma Haoliang Qian Werner Jiang Collaborators: Prof. Shaya Fainman (UCSD) Prof. Eric Fullerton (UCSD) Prof. Xiang Zhang (Berkeley) Prof. Yu-Hwa Lo (UCSD) Prof. Deli Wang (UCSD) Prof. Sungho Jin (UCSD) Prof. Renkun Chen (UCSD) Kok Wai Cheah (Hong Kong Baptist Univ.)

Breaking the imaging symmetry in negative refraction lenses

$Breaking the imaging symmetry in negative refraction lenses$ Breaking the imaging symmetry in negative refraction lenses Changbao Ma and Zhaowei Liu* Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92093-0407,