1

Experiments on Superconducting Metamaterial-Induced Transparency Cihan Kurter, John Abrahams, Chris Bennett, Tian Lan, Steven M. Anlage,

L. Zhang, T. Koschny, C. Soukoulis (Ames/Iowa State)Alexander Zhuravel (Kharkov, Ukraine),

Alexey Ustinov (KIT, Karlsruhe, Germany),

Work Funded by NSF and ONR

Metamaterials 2010, Karlsruhe, Germany14 September, 2010

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Metamaterial-Induced Transparency

Inspired by:Electromagnetically-Induced Transparency (EIT)

Light can be slowed, or even stopped at the EIT frequencyL. V. Hau, Nature (1999)Fleischhauer, PRL (2000)

N. Papasimakis, et al.Optics and PhotonicsNews, Oct. 2009Classical Analog of EIT

Garrido Alzar, et al.,Am J Phys (2002)

Strong dispersionwith little loss

12Dissipation 2 << 1

to coherently driveparticle 1

Atom

Probe FieldPump Field

Probe Frequency Probe Frequency

Pro

be

Ab

sorp

tion

3

Re[

x 1(t)

]

Atom

Probe Field

Pump Field

The “atom” has zero displacement at the EIT frequency, but largedisplacement for small de-tuning

12

2 << 1

1 = 4.0 x 10-2

2 = 1.0 x 10-7

Classical Analog of EITThe Importance of Strong Loss Contrast

Ab

sorb

ed P

ower

0 .98 0 .99 1 .00 1 .01 1 .020

50

10 0

15 0

Frequency

Ab

sorp

tion

2 = 1 x 10-7

2 = 1 x 10-3

2 = 1 x 10-2

1 = 4 x 10-2

4

l1

w1

g

l2

l3

w2

s1s2

ax

ay

Metamaterial-Induced TransparencyWork with L. Zhang, T. Koschny, and C. Soukoulis (Iowa State Univ.)

Cu (radiative)Normal metal

Nb (dark)Superconducting

X-band waveguide

Normal metal metamaterials:Papasimakis, PRL 2008Tassin, PRL 2009

Superconducting MetamaterialsMIT @ 10 GHz

E

B

Cu NbNb

12

5

Simulation ResultsMetamaterial-Induced Transparency

9 10 11 12

0.01

1

0.1

Frequency (GHz)

T,R

TR

Inde

x of

Ref

ract

ion

Tra

nsm

issi

on a

nd

Ref

lect

ion

EIT Frequency

Adjust coupling to dark resonatorsand frequencies of dark resonatorsto modify n() dispersion

9.5 10 10.5 11

0

2

4

6

8

10

Frequency (GHz)

n

(n)(n)

L. Zhang, T. Koschny, and C. Soukoulis (Iowa State Univ.)

6

Experimental SetupMetamaterial-Induced Transparency

CryogenicDewar

X-bandWaveguideSample

NetworkAnalyzer

CoaxialCable

1 2

7

0 .0 0 .5 1 .0 1 .5 2 .0 2 .5 3 .0 3 .5

0 .2

0 .4

0 .6

0 .8

1 .0

0 .0 0 .5 1 .0 1 .5 2 .0 2 .5 3 .0 3 .5

0 .2

0 .4

0 .6

0 .8

1 .0

00

1()

2()

1()

2() ~ 1/

i

Superconductor Electrodynamics

“binding energy” of Cooper pair (100 GHz ~ few THz)

T = 0ideal s-wave

/0iiXRZ sss Surface Impedance (> 0)

Normal State

11

0 1

2 ss XR

Superconducting State ( < 2)

01 0~ ss XR

Penetration depth(0) ~ 20 – 200 nm

nsem

Finite-temperature: Xs(T) = L = (T) → ∞ as T →Tc

Narrow wire or thin film of thickness t : L(T) = (T) coth(t/(T)) → 0 2(T)/tKinetic Inductance

Superfluid density2 ~ m/ns

T

ns(T)

Tc00

/2

Normal State (T > Tc)(Drude Model)

1/

EJ

T

1(T)

Tc00

n

8

Experimental ResultsMetamaterial-Induced Transparency

Nb / Cu MM-EIT sample (first generation) in Cu waveguide

9.70 9.75 9.80 9.85 9.90

-25

-20

-15

-10

-5

0

5

Frequency (GHz)

Tra

nm

siss

ion

|S21

|/|S

21|m

ax (

dB

)

-40

-30

-20

-10

0

10

20

30

40

50

Un

calib

rate

d G

rou

p D

ela

y (ns)

EIT bandwidth (3 dB) = 7.5 MHz (~ 0.1%)

Pin = -30 dBmT = 4.6 K

d

d 12~

9

9.68 9.70 9.72 9.74 9.76 9.78 9.80 9.82 9.84 9.86 9.88

-40

-35

-30

-25

-20

-15

Tra

nsm

issi

on

|S21

| (d

B)

f (GHz)

4.9 K 5 K 6 K 7 K 7.5 K 7.8 K 8 K 8.2 K 8.4 K 8.5 K 8.6 K 8.7 K 8.75 K 8.8 K 8.83 K 8.86 K 8.89 K 8.92 K 8.95 K 8.98 K 9 K 9.04 K 9.1 K 9.2 K 9.3 K

Frequency (GHz)

Tra

nsm

issi

on |S

21|/|

S21

|max

(dB

)0

-5

-10

-15

-20

-25

Superconducting Metamaterial-Induced TransparencyEffect of Temperature on Transmission

5 6 7 8 99.76

9.77

9.78

9.79

f 0 (p

eak) (

GH

z)

T(K)Temperature (K)

f 0(p

eak

) (G

Hz)

5 6 7 8 9-22

-20

-18

-16

-14

|S21

| peak

(d

B)

T(K)Temperature (K)

|S21

| (p

eak

) /|S

21| m

ax(p

eak

) (d

B)

0

-2

-4

-6

-8

10

Superconducting Metamaterial-Induced TransparencyEffect of Temperature on Group Delay

9.72 9.74 9.76 9.78 9.80 9.82 9.84 9.860

10

20

30

40

50

60

70

Un

calib

rate

d G

rou

p D

elay

(n

s)

Frequency (GHz)

4.9 K_smt 7 K_smt 7.8 K_smt 8.2K_smt 8.4 K_smt 8.6 K_smt 8.7 K_smt 8.75 K_smt 8.8 K_smt 8.83 K_smt 8.86 K_smt 8.89 K_smt 8.92 K_smt 8.95 K_smt 8.98 K_smt 9 K_smt 9.1 K_smt 9.2 K_smt 9.3 K_smt

Pin = -30 dBm

5 6 7 8 99.76

9.77

9.78

9.79

Temperature (K)

f 0 (p

eak) (

GH

z)

5 6 7 8 935

40

45

50

55

60

65

70

Temperature (K)

Pea

k G

rou

p d

elay

(n

s)

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Experimental ResultsMetamaterial-Induced Transparency

Switching/Limiting Behavior at High Power

The “transparencywindow” switchesoff between +17 and+18 dBm

9.70 9.75 9.80 9.85 9.90

-25

-20

-15

-10

-5

0

5

T= 4.24 K

Tra

nsm

issi

on

|S21

|/|S

21|m

ax (

dB

)

Frequency (GHz)

P= -30 dBm P= -10 dBm P= 17dBm P= 18dBm P= 20dBm

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RF Power Dependence of Superconducting EIT Features

To investigate the RF power dependence, we examine the RF currentdistributions in the superconducting parts of the sample using Laser Scanning Microscopy (LSM)

1 mm

T = 79.5 Kf = 5.2133 GHzP = - 6 dBm

10 V

0 V

8.5 mm

RF photoresponse~ Jrf

2(x, y) Scanned Area

RF inputRF output

YBCO Ground Plane

YBCO Ground Plane

STO Substrate

240 nm thick film

LAO

ff0

|S21(f0)|2

|S21(f0)|2laser OFF

laser ON

resonator transmission

|S12|2 ~ [ JRF(x,y)]2 A

PoutPin

modulatedlaser

See A. P. Zhuravel, et al.,J. Appl. Phys. 108, 033920 (2010)

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f = 9.63 GHz; P = 18 dBm; T = 7 K

LSM Image of Superconducting RF Currents in EIT sample @ 10 GHz

Upper Nb split ring

Bottom

Geometry 2D LSM image

Focus on this cornerNb split ring

Cu stripe

Current flow numerical simulation, L. Zhang, et al. (Ames)

C. Kurter, et al., arXiv:1008.2020

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RF Power Dependence of LSM Photoresponse in a Corner of the Nb Split Ring

15 dBm 20 dBm

20.8 dBm 21 dBm 22 dBm

20.6 dBm

2~ RFJ

Quartzsubstrate

Nb film

100 m

100 m

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Future Directions forSuperconducting EIT Metamaterials

Calibrated and de-embedded S21 and group delay measurements

Rounded-corner samples for better tunability at high power

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Conclusions

Demonstrated Superconducting Metamaterial-Induced TransparencyTunable with variable Kinetic Inductance and RF magnetic fields

Demonstrated Tunability of features:Temperature tuning (kinetic inductance → plasmonic regime)RF Magnetic Field tuning (magnetic Abrikosov vortices, JRF peaks)

Superconducting Metamaterials Review Article (J. of Optics, in press):arXiv:1004.3226

Work Funded by NSF, ONR.

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Stirling cycle cryocooler

MTBF > 106 hours

2.8 kg92 mm OD x 300 mm

5W cooling power @ 77 K

STI “AmpLink” Filter1850 – 1910 MHzPCS band

CryoCoolers and CryoPackaging

Small, inexpensive and reliable cryocoolers are available

Many companies buildcryo-cooled microwaveand high-speed digital

products

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19

Outline

Losses in Metamaterials

Review article on Superconducting Metamaterials (J. of Optics) arXiv:1004.3226

Brief Review of Superconductor Electrodynamics

New Features Enabled by Superconductivity

Low loss (+ inductance) enables very compact ‘atoms’

New sources of inductance

New sources of nonlinearity and gain

New ‘Atoms’

Some Novel Applications of Superconducting Metamaterials

Future Prospects + Conclusions

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Why Superconducting Metamaterials?

The exciting novel applications of metamaterials:Flat-slab Imaging“Perfect” ImagingCloaking DevicesIllusion Opticsetc. …

SUPERCONDUCTING METAMATERIALS: Can achieve these requirements!

… have strict REQUIREMENTS on the metamaterials:Low LossesUltra-small size “atoms” (size << wavelength) Tunability / Texturing of the index of refraction n

CloakingDevices

(Engheta, Leonhardt,Pendry, Milton)

LHMRHM RHM

Pointsource “perfect image”

Flat LensImaging

Illusion Optics (Lai)

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Outline

Losses in Metamaterials

Brief Review of Superconductor Electrodynamics

New Features Enabled by Superconductivity

Low loss (+ inductance) enables very compact ‘atoms’

New sources of inductance

New sources of nonlinearity and gain

New ‘Atoms’

Some Novel Applications of Superconducting Metamaterials

Future Prospects + Conclusions

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T

1(T)

Tc00

n

23

0 .99 1 .00 1 .01 1 .02

50 00

0

50 00

10 00 0

15 00 0

20 00 0

24

0 .98 0 .99 1 .00 1 .01 1 .020

50

10 0

15 0

Frequency

Ab

sorp

tion

2 = 1 x 10-7

2 = 1 x 10-3

2 = 1 x 10-2

1 = 4 x 10-2

25

9.5 10 10.5 11

0

2

4

6

8

10

Frequency (GHz)

n

(n)(n)

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Experimental ResultsMetamaterial-Induced Transparency

9.65 9.70 9.75 9.80 9.85 9.90 9.95

-60.0n

-50.0n

-40.0n

-30.0n

-20.0n

-10.0n

0.0

10.0n

20.0n Pinput= -30 dBm,T=4.6KIFBW=300 Hz

groupDelay

Frequency (GHz)

Gro

up D

elay

(se

c)

-32

-30

-28

-26

-24

-22

-20

-18

-16

-14

-12

-10

-8

-6

s21MAG

Transm

ission |S21 | (dB

)

This includestransmission lossesin cold cables andwaveguide

Nb / Cu MM-EIT sample (first generation) in Cu waveguide

27

Experimental ResultsMetamaterial-Induced Transparency

Switching/Limiting Behavior at High Power

9.60 9.65 9.70 9.75 9.80 9.85 9.90 9.95-35

-30

-25

-20

-15

-10

-5 Tbath

= 4.24 K|S

21| (

dB

)

f(GHz)

P= -30 dB P= -10 dB P= 17dB P= 18dB P= 20dB

Frequency (GHz)

|S21

| (d

B)

The “transparencywindow” switchesoff between +17 and+18 dBm

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Laser Scanning Microscopy of RF CurrentsPrinciple of the Measurement

Work with A. Zhuravel (Kharkov) and A. Ustinov (Karlsruhe)

Pout

ff0

|S21(f0)|2

|S21(f0)|2laser OFF

laser ON

co-planar resonator f0 ~ 5.2 GHz

Pin

modulatedlaser

resonator transmission

Local heating produces a change in transmission coefficient proportionalto the local value of JRF

2

J. C. Culbertson, et al. J.Appl.Phys. 84, 2768 (1998)

A. P. Zhuravel, et al., Appl.Phys.Lett. 81, 4979 (2002)

|S12|2 ~ [ JRF(x,y)]2 A

29

1 mm

T = 79.5 Kf = 5.2133 GHzP = - 6 dBm

10 V

0 V

2-D Response Map for RF Current Distribution of a Sample

Fundamental resonance mode (5.2 GHz)

8.5 mm

RF photoresponse~ Jrf

2(x, y) Scanned Area

RF inputRF output

YBCO Ground Plane

YBCO Ground Plane

STO Substrate

240 nm thick film

LAO

30

1 mm

T = 79.5 Kf = 5.2133 GHzP = - 6 dBm

10 V

0 V

8.5 mm

RF photoresponse~ Jrf

2(x, y) Scanned Area

RF inputRF output

YBCO Ground Plane

YBCO Ground Plane

STO Substrate

240 nm thick film

LAO

31

0 1 2 3 4 5 6 7 8 9-2

0

2

4

6

8

10

12

14

16

18

20

22

P r

esp

on

se, a

.u

X, mm

T=79.5 K with 8672 A Generator P=-6 dBm in scale of 8672A Fmod=99.99 kHz

f=5.2133 GHz

Standing Wave JRF Pattern at Fundamental Frequency

2D image

Pho

tore

spon

se (

a.u.

)

62.439.0cos16~ 2 xPRFit:

kfit = 0.39 mm-1

ktheory = 0.42 mm-1

Proof that measured PR ~ JRF2 to first order approx.