Superconducting Electromagnetic Metamaterials Steven M. Anlage, Michael Ricci, Nathan Orloff Fermilab 23 May, 2007 Work Funded by NSF/ECS-0322844

Negative Refraction: Consequences Left-Handed or Negative Index of Refraction Metamaterials e < 0 AND m < 0 Veselago, 1967 Propagating waves have index of refraction n < 0  Phase velocity is opposite to Poynting vector direction Negative refraction in Snell’s Law: n1 sinq1 = n2 sinq2 Flat lens with no optical axis Converging Lens → Diverging Lens and vice-versa “Perfect” Lens (Pendry, 2000) Reverse Doppler Effect Reversed Čerenkov Effect Radiation Tension LHM RHM Point source “perfect image” Flat Lens Imaging Cloaking Devices (Engheta, Leonhardt, Pendry, Milton) V. G. Veselago, Usp. Fiz. Nauk 92, 517 (1967) [Eng. Trans.: Sov. Phys. Uspekhi 10, 509 (1968)]

Metamaterial vs Photonic Crystal wavelength l elementary units or “atoms” Create an “effective medium,” using engineered “atoms,” with macroscopic eeff, meff, n properties Metamaterial a Photonic Crystal a ~ l Use constructive and destructive interference to engineer properties of light → band structure band gaps defect states negative group velocity …

Superconducting Metamaterials How to make them: Step 1 All-Nb X-band waveguide + couplers Nb X-band waveguide (22.86 x 10.16 mm2) Tc = 9.25 K Thanks to P. Kneisel @ JLab 4.57 mm Nb Wires 0.25 mm dia. Tc = 9.25 K What are we doing? 10.2 mm 22.9 mm Nb Wires

Superconducting Metamaterials How to make them: Step 2 Nb film, ~ 200 nm thick 0.89 cm 3.0 cm 2.36 mm 0.3 mm 0.154 mm Nb SRR 200 nm thick on Quartz (350 mm) Tc = 8.65 K B E k

Overlap of eeff < 0 and meff < 0 to make n < 0 216 SRRs in out Negative Index Passband in a Superconducting Metamaterial 216 SRRs in a 12-cell wire array, 9 cm long Overlap of eeff < 0 and meff < 0 to make n < 0 Increasing temperature Transmission Superconducting Normal Metal Negative Index of Refraction wire array plasma edge

Metamaterials: Novel Applications Thin SubWavelength Cavity Resonators (Engheta, 2002) For a resonance in the z-direction: New possibility – zero net phase winding p = 0 “zeroth order resonance” z 0th resonance condition independent of d1 + d2 and depends only on d1/d2 RHM LHM n1>0 n2<0 Conducting planes p can also be a negative integer!

Split-Ring Resonators Implementation of an LHM Compact Waveguide Novel LHM Pass Band Waveguide 2 cm e < 0 Transmission |S21| (dB) e > 0 Split-Ring Resonators (SRRs) Provide m < 0 at 350 MHz Frequency (GHz) Hrabar, et al., 2005 Measured transmission |S21| parameter of miniaturized waveguide (a = 16 mm) filled with metamaterial based on capacitively loaded rings. The ordinary cutoff of the waveguide is 7 GHz, while the SRRs produce a LHM pass band at 350 MHz.

SC metamaterials papers: Appl. Phys. Lett. 87, 034102 (2005) Conclusions Negatively Refracting Metamaterials offer opportunities for a new kind of optics Negative Index of Refraction Flat Lens Imaging Amplification of Evanescent Waves “Super Lenses” There are many new Emerging Applications Compact (dual TL) structures with enhanced performance Composite LHM/RHM materials with unique field structures New antenna structures Novel optics / NIR lithography Recovering Evanescent fields SC metamaterials papers: Appl. Phys. Lett. 87, 034102 (2005) Appl. Phys. Lett. 88, 264102 (2006) anlage@umd.edu

What Else Can Be Done? Higher Frequencies Smaller size “atoms” Low-Loss Limited only by SC gap frequency Nb: 2D/ħ ~ 1 THz HTS: 2D/ħ ~ 10 THz Size Scaling Losses remain small as dimensions shrink Enhanced Inductance Tricks: Thinner films – Enhanced Kinetic Inductance Josephson Junctions – Enhanced and tunable inductance Novel Effects Unique to Superconductors: SQUID – the ultimate low-loss tunable SRR Josephson Junction Array collective dynamics

Metamaterials: Novel Applications Amplification of evanescent waves Super-resolution imaging Perfect absorber condition Reversed Doppler effect Tunable reflection phase properties New guided mode structures Reversed optics Compact size and light weight electromagnetic structures

Metamaterials: Novel Antennas Directional Antenna with n ~ 0 A point source embedded in a metamaterial with n~0 will produce a directed beam nearly normal to the metamaterial/vacuum interface. From [Enoch2002]. Super-Efficient Electrically-small Dipole Antenna (ℓ << l) RHM LHM Small dipole antenna Ziolkowski (2003) LHM shell compensates Im[ZAnt] Factor of 74 improvement in PRad at 10 GHz with l/1000 antenna

Split-Ring Resonators Implementation of an LHM Compact Waveguide Novel LHM Pass Band Waveguide 2 cm e < 0 Transmission |S21| (dB) e > 0 Split-Ring Resonators (SRRs) Provide m < 0 at 350 MHz Frequency (GHz) Hrabar, et al., 2005 Measured transmission |S21| parameter of miniaturized waveguide (a = 16 mm) filled with metamaterial based on capacitively loaded rings. The ordinary cutoff of the waveguide is 7 GHz, while the SRRs produce a LHM pass band at 350 MHz.

RHM/LHM/RHM resonator is 86% smaller Implementation of an LHM Compact Resonator RHM/LHM/RHM Conventional RHM Both resonate at 1.2 GHz RHM/LHM/RHM resonator is 86% smaller Scher, et al., 2004 Microstrip Resonators RHM Transmission Lines LHM Transmission Line (Dual structure)

Negative Index Microwave Circuits Dual Transmission Lines with NIR concepts are leading to a new class of microwave devices Compact couplers, resonators, antennas, phase shifters have been demonstrated 1.9 GHz 0th-order resonator T. Itoh, et al., UCLA