volume | PIER Journals

Abstract

Materials that exhibit negative refraction may have many novel applications. We seek to evaluate the possibility of soft-focusing of microwave signals using a medium with an indefinite (hyperbolic) anisotropic permittivity tensor. We fabricated a 147 mm thick and 220 mm wide Styrofoam sample with an embedded array of 12-gauge brass wires of 6.35 mm lattice spacing. Two single-loop antennas were used to approximately generate a transverse magnetic (TM) point source and the associated detector. Using an Agilent 8510C Vector Network Analyzer (VNA), the frequency spectrum was scanned between 7 and 9 GHz. Relative gain or loss measurements were taken at equal spatial steps behind the sample. A scanning robot was used for automatic scanning in the x, y, and z directions, in order to establish the focusing patterns. The signal amplitudes measured in the presence and absence of the sample were compared. The robot was controlled using LabVIEW¹, which also collected the data from the VNA and passed it to MATLAB² for processing. A soft focusing spot was observed when the antennas were placed in two different symmetric configurations with respect to the sample. These results suggest a method for focusing electromagnetic waves using negative refraction in indefinite (hyperbolic) anisotropic materials.

1. Pendry, J. B., A. J. Holden, W. J. Stewart, and I. Youngs, "Extremely low frequency plasmons in metallic mesostructures," Physical Review Letters, Vol. 76, No. 25, 4773-6, 1996.
doi:10.1103/PhysRevLett.76.4773

2. Smith, D. R., W. J. Padilla, D. C. Vier, S. C. Nemat-Nasser, and S. Schultz, "A composite medium with simultaneously negative permeability and permittivity," Physical Review Letters, Vol. 84, 4184-7, 2000.

3. Veselago, V. G., "The electrodynamics of substances with simultaneously negative values of ε and μ," Soviet Physics USPEKHI, Vol. 10, No. 4, 509, 1968.
doi:10.1070/PU1968v010n04ABEH003699

4. Pendry, J. B., "Negative refraction makes a perfect lens," Physical Review Letters, Vol. 85, No. 18, 3966-9, 2000.
doi:10.1103/PhysRevLett.85.3966

5. Shen, N. H., S. Foteinopoulou, M. Kafesaki, T. Koschny, E. Ozbay, E. N. Economou, and C. M. Soukoulis, "Compact planar far-field superlens based on anisotropic left-handed metamaterials," Physical Review Letters B, Vol. 80, 115123, 2009.

6. Driscoll, T., D. N. Basov, A. F. Starr, P. M. Rye, S. Nemat-Nasser, D. Schurig, and D. R. Smith, "Free-space microwave focusing by a negative-index gradient lens," Applied Physics Letters, Vol. 88, 081101-1-3, 2006.

7. Smith, D. R. and D. Schurig, "Electromagnetic wave propagation in media with indefinite permittivity and permeability tensors," Physical Review Letters, Vol. 90, No. 7, 077405-1-4, 2003.
doi:10.1103/PhysRevLett.90.077405

8. Smith, D. R., P. Kolinko, and D. Schurig, "Negative refraction in indefinite media," Journal of the Optical Society of America B: Optical Physics, Vol. 21, No. 5, 1032-1042, 2004.
doi:10.1364/JOSAB.21.001032

9. Liu, H., Q. Lv, H. Luo, S. Wen, W. Shu, and D. Fan, "Focusing of vectorial fields by a slab of indefinite media," Journal of Optics A: Pure and Applied Optics, Vol. 11, 105103, 2009.
doi:10.1088/1464-4258/11/10/105103

10. Fang, A., T. Koschny, and C. M. Soukoulis, "Optical anisotropic metamaterials: Negative refraction and focusing," Physical Review Letters B, Vol. 79, 245127, 2009.

11. Cheng, Q. and T. J. Cui, "Planar microwave lens based on complementary metamaterials," 2010 IEEE Antennas and Propagation Society International Symposium (APSURSI), 1-4, 2010.

12. Salandrino, A. and N. Engheta, "Far-field subdiffraction optical microscopy using metamaterial crystals: Theory and simulations," Physical Review Letters B, Vol. 74, 075103, 2006.

13. Schurig, D. and D. R. Smith, "Spatial filtering using media with indefinite permittivity and permeability tensors," Applied Physics Letters, Vol. 82, No. 14, 2215-7, 2003.
doi:10.1063/1.1562344

14. Smith, D. R., D. Schurig, J. J. Mock, P. Kolinko, and P. Rye, "Partial focusing of radiation by a slab of indefinite media," Applied Physics Letters, Vol. 84, No. 13, 2244-6, 2004.
doi:10.1063/1.1690471

15. Nemat-Nasser, S. C., A. V. Amirkhizi, W. J. Padilla, D. N. Basov, S. Nemat-Nasser, D. Bruzewicz, and G. Whitesides, "Terahertz plasmonic composites," Physical Review E, Vol. 75, 036614-1-7, 2007.

16. Smith, D. R., D. C. Vier, W. J. Padilla, S. C. Nemat-Nasser, and S. Schultz, "Loop-wire medium for investigating plasmons at microwave frequencies," Applied Physics Letters, Vol. 75, No. 10, 1425-7, 1999.
doi:10.1063/1.124714

17. Nemat-Nasser, S., S. C. Nemat-Nasser, T. Plaisted, A. Starr, and A. V. Amirkhizi, "Multifunctional materials," BIOMIMETICS: Biologically Inspired Technologies, Y. Bar-Cohen, Ed., 309-341, CRC Press, 2005.

18. Marshall, S., A. V. Amirkhizi, and S. Nemat-Nasser, "Focusing and negative refraction in anisotropic indefinite permittivity media," Proceedings of the International Society for Optical Engineering Electroactive Polymer Actuators and Devices (EAPAD), Y. Bar-Cohen, T. Wallmersperger (eds.), San Diego, 2009.

Ms. Sara Wheeland

Dr. Alireza V. Amirkhizi

Dr. Sia Nemat-Nasser