Efficient focusing based on fishnet negative index metamaterial lenses at radio frequencies

Size: px

Start display at page:

Download "Efficient focusing based on fishnet negative index metamaterial lenses at radio frequencies"

Olivia Barber
6 years ago
Views:

1 Efficient focusing based on fishnet negative index metamaterial lenses at radio frequencies W. Sfar Zaoui *, M. Nafe, M. Geng, W. Vogel, M. Berroth CST EUC 214 Berlin, May 7 th 9 th 1

Andryieuski C. Menzel W. Vogel M. Nafe A. Lavrinenko C.

2 Acknowledgment Institute of Electrical and Optical Communications Engineering W. Sfar Zaoui K. Chen A. Andryieuski C. Menzel W. Vogel M. Nafe A. Lavrinenko C. Rockstuhl M. Berroth M. Geng Y. Sachkou Contract No. BE 2256/11-1 BE 2256/

INT research topics High-speed mixed-signal IC design CMOS: 12 nm,

RF-amplifiers, -oscillators, Mixed signal: High-speed ADCs and

56 Gbit/s, 1 Gbit-Ethernet High complexity (> 4.

equalizer (9 nm CMOS) Circuit design, simulation, layout

Fabrication by foundry (STM, TSMC, IHP) via CMP or EUROPRACTICE or

3 INT research topics High-speed mixed-signal IC design CMOS: 12 nm, 9 nm, 65 nm, 4 nm, 28 nm BJT: SiGe- SiGe-BiCMOS, InP Analog: RF-amplifiers, -oscillators, Mixed signal: High-speed ADCs and DACs, Digital: Viterbi- & OFDM-DSPs, MUX, DEMUX Data rates up to 56 Gbit/s, 1 Gbit-Ethernet High complexity (> 4. transistors) 36 GS/s 3 bit ADC (65 nm CMOS) 4 Gbit/s Viterbi equalizer (9 nm CMOS) Circuit design, simulation, layout Characterisation and measurement 25 GHz analog multiplexer InP HBT Fabrication by foundry (STM, TSMC, IHP) via CMP or EUROPRACTICE or by industry partner (GF, Infineon, etc ) OFDM chip (65 nm CMOS) 25 Gbit/s ADC real time interface to FPGA 3

INT research topics Optoelectronic devices Design and simulation of integrated waveguiding

measured -2 LCA, de-embedded -3 db -3 λ = 155 nm -4 D = 1 µm V Bias = -2 V Design and

contact structure -5-6 1 1 5 Frequency / GHz Si/Ge photodetectors, modulators, grating

characterization (electrical, optical) Integrated waveguide structures Fabrication by epixfab,

4 INT research topics Optoelectronic devices Design and simulation of integrated waveguiding systems, senders, receivers R TT C TT AC R 1 R 2 C D R DS R D C P R P L S S 21 / db 1-1 LCA, measured -2 LCA, de-embedded -3 db -3 λ = 155 nm -4 D = 1 µm V Bias = -2 V Design and simulation, modelling, characterization Silicon photonics transit time VCVS inner diode contact structure Frequency / GHz Si/Ge photodetectors, modulators, grating couplers, multi-mode-interferometers Device modelling (electrical, optical) Device characterization (electrical, optical) Integrated waveguide structures Fabrication by epixfab, IMS, IHT, IHP, Basic research on photonic crystals and negative index metamaterials Negative-indexmaterials and photonic crystals 4

5 Contents Motivation Realization of negative index metamaterials Single layer design Multilayer design Fabrication and characterization Aberration-free focusing based on NIM lenses Simulation results Measurement results Summary 5

6 Motivation Metamaterials: Artificial materials with properties not found in nature Periodic structures with period << wavelength ( photonic crystals) Effective internal parameters with arbitrary values E.g. ε r < and μ r < n = ε r μ r < negative index metamaterials (NIM) phys.org 6

7 Transformation optics cmth.ph.ic.ac.uk sciencegymnasium.com nextbigfuture.com 7

$Superlensing through negative refraction λ = 7.$ d) n = -1 Normalized intensity 1..8.6.4.

intensity 1..8.6.4.2 Source Field at z = 2d.

8 Superlensing through negative refraction λ = 7.5 mm 2d λ /2 λ /2 2d Air n = 1 NIM (thickness d) n = -1 Normalized intensity Source Field at z = 2d λ /8 Normalized intensity Source Field at z = 2d Lateral position [mm] Lateral position [mm] 8

$Efficient focusing through negative refraction Plano-convex$ 45 f ~ 1 mm Plano-concave NIM lens f ~ 35 mm n = -1 Focal

9 Efficient focusing through negative refraction Plano-convex dielectric lens n = 1.45 f ~ 1 mm Plano-concave NIM lens f ~ 35 mm n = -1 Focal length (in the paraxial limit) f R n 1 Normalized intensity NIM lens Dielectric lens Lateral position [mm] NIM plano-concave lenses offer tighter focus than conventional dielectric plano-convex lenses 9

10 Motivation Realization of negative index metamaterials Single layer design Multilayer design Characterization of the fabricated NIM Aberration-free focusing based on NIM lenses Simulation results Measurement results Summary 1

Some possible NIM designs E k H Metal Dielectric E (

Compact dimensions Fishnet + Flat design +

11 Some possible NIM designs E k H Metal Dielectric E ( H ) k H ( E ) W. Sfar Zaoui et al., PNFA 1 (212) Split ring resonator - Polarization dependent - High losses - Low magnetic resonance + Compact dimensions Fishnet + Flat design + Polarization independent + Low losses + High magnetic resonance - Large lattice constant 11

Walls F-solver F-solver T-solver -5-5 -5, S 21 [db] -1-15 -2-25 S 21, S 21

12 The fishnet design: Boundary conditions 1 unit cell Floquet boundaries ¼ unit cell Perfect el./mag. Walls F-solver F-solver T-solver , S 21 [db] S 21, S 21 [db] S 21, S 21 [db] S GHz GHz GHz

13 Single layer design a R Metal (Copper) d m = 17.5 μm Dielectric (Duroid588) d s = 25 μm L o R o C/2 C L o R o d = d s + 2d m L m L m w E.g.: a = 4.9 mm R = 2.3 mm w = 1.45 mm C =.6 ff L o = L u =.1 nh L m =.212 nh R o = R u = R m = 1 Ω R m L u R u C C/2 R m L u R u ADS: Advanced Design System, S 21 [db] S 21 CST -25 CST -3 S 21 ADS ADS arg (S 11 ), arg(s 21 ) [rad] arg(s ) CST arg(s 11 ) CST 3. arg(s 21 ) ADS arg(s 11 ) ADS

14 Retrieving the effective internal properties Relative impedance Refractive index Figure of merit z = ± ( 1 S ) ( 1 S ) * 2 * 2 11 S21 * 2 * 2 11 S21 + jnk { ( )} ( ) d jnk 2 d π { } 1 n = Im ln e + m j Re ln e kd * jnkd S21 with e = * z 1 1 S11 z + 1 Re( n ) FOM = Im( n ) Relative permittivity n ε r = Relative permeability µ r = nz z NB: Use of conjugate complex due to difference between used conventions X. Chen et al., Phys. Rev. E 7 (24) Literature (physics) jωt jkz E= Ee e CST (electrical engineering) jωt jkz E= Ee e 14

15 Retrieving the effective internal properties Re(z), Im(z) 1..5 Re(z). Im(z) Relative impedance Re(n), Im(n) Im(n) Re(n) Refractive index FOM Figure of merit Re(ε r ), Im(ε r ) Im(ε r ) Re(ε r ) Re(µ r ), Im(µ r ) Im(µ r ) Re(µ r ) Very high FOM owing to the low absorption losses Relative permittivity Relative permeability 15

45 mm d spacer = mm, S 21 [db] -2-4 -6-8 -4.

16 Multilayer design Weak coupling 2.2 mm 5 mm 2.3 mm 4.9 mm Strong coupling 1.8 mm d spacer =.5 mm 1.45 mm d spacer = mm, S 21 [db] db S 21, S 21 [db] db S M. Nafe et al., ASAT,

Dispersion diagram Weak coupling Strong coupling 8 Mode 4 8 Mode 3 7 6 5 Mode 3 Mode 2 Negative slope 7 6 5 Mode 2 4 Mode 1 4 Mode 1 E-solver Periodic boundaries in z-direction N Re(n) -1-2..5 1. 1.5 2.

17 Dispersion diagram Weak coupling Strong coupling 8 Mode 4 8 Mode Mode 3 Mode 2 Negative slope Mode 2 4 Mode 1 4 Mode 1 E-solver Periodic boundaries in z-direction N Re(n) Phase β z [rad] { ( )} si gn Re n -3 N = 1 N = 3-4 N = 5 N = 1 N = ω = sign β z Re(n) Phase β z [rad] N = 1-1 N = 5 N = 1-12 N = 2 N =

18 Negative phase advance N = 1 a = 4.9 mm R = 2.3 mm w = 1.45 mm Negative phase advance 18

Characterization of the fabricated single layers Fabricated functional layer, S 21 [db] -5-1 -15-2 -25-3 S 21 Vector network analyzer Simulation Measurement 3 35 4 45 d Re(n), Im(n) 2 15 1 5

19 Characterization of the fabricated single layers Fabricated functional layer, S 21 [db] S 21 Vector network analyzer Simulation Measurement d Re(n), Im(n) Receiving horn antenna NIM Transmitting horn antenna Im(n) Calibration method: Thru-Reflect-Match (TRM) T: free space R: metal plate M: absorber material -5 Re(n) -1 Simulation Measurement

Characterization of the NIM multilayer arg (S 21 ) [rad] 4 3 2 1 N = 5 N = 1 N = 1 n c ϕ = d ω W. Sfar Zaoui et al.

20 Characterization of the NIM multilayer arg (S 21 ) [rad] N = 5 N = 1 N = 1 n c ϕ = d ω W. Sfar Zaoui et al., WRCM, Simulation Measurement , S 21 [db] Retrieval method fails -5 here due to propagation of several Bloch modes S 21 (inhomogeneous material) Simulation Measurement Re(n), Im(n) Im(n) Re(n) -6 Simulation Measurement GHz S 21 = -.47 db = -1.5 db Re(n) =

21 Motivation Realization of negative index metamaterials Single layer design Multilayer design Characterization of the fabricated NIM Aberration-free focusing based on NIM lenses Simulation results Measurement results Summary 21

.5 y x 53.9 mm. 5 1 15 2 E-field @ 38.5 GHz x [mm] Max.

22 Simulation results Spherical curve approximation R = 75 mm y [mm] y x 53.9 mm GHz x [mm] Max. Focal plane 44.8 mm Normalized intensity FWHM = 8.6 mm Min Lateral position [mm] 22

-35 Measured reflection < -14 db Q-band 1 2 3 4 5 xy-table Receiving

23 Near/far-field measurement setup Gain max = 7.55 db a = 5.7 mm b = 2.85 mm 5 Open ended waveguide antenna (OEWG) a b [db] Measured reflection < -14 db Q-band xy-table Receiving OEWG antenna DUT 55 mm Vector network analyzer Transmitting horn antenna 23

24 Measurement results W. Sfar Zaoui et al., WRCM, 214 Fabricated sample S 38.5 GHz Min. Max. 1. Free space Gain = 7 db NIM lens Focal plane 44 mm Normalized transmission FWHM = 8.9 mm Lateral position [mm] 24

55 mm Dielectric lens Transmitting horn antenna Focal plane 95 mm At focus point.

25 Measurement results x z y xy-table Measurement setup Receiving OEWG antenna Aspheric dielectric lens x 2 + y 2 = ε r 1 z 2 + 2f ε r 1 z S 21 Min GHz Network analyzer mm Dielectric lens Transmitting horn antenna Focal plane 95 mm At focus point.4 db lower transmission than NIM lens! Normalized transmission FWHM = 19 mm Lateral position [mm] 25

26 Motivation Realization of negative index metamaterials Single layer design Multilayer design Characterization of the fabricated NIM Aberration-free focusing based on NIM lenses Simulation results Measurement results Summary 26

27 Summary Metamaterials offer molding the flow of light in a flexible fashion (transformation optics, clocking, lensing, etc.) NIM fishnet allows high transmission, low absorption, and low reflection (~ -.5 db efficiency achieved) Plano-concave configurations offer tighter focus, lower spherical aberrations, shorter focal length, and lighter weight than conventional dielectric lenses (FWHM and focal length decreased by a factor of 2) 27

Gradient-index metamaterials and spoof surface plasmonic waveguide

Gradient-index metamaterials and spoof surface plasmonic waveguide Hui Feng Ma State Key Laboratory of Millimeter Waves Southeast University, Nanjing 210096, China City University of Hong Kong, 11 October