[Journal Articles][Conference Papers]

Richard Averitt Assistant Professor Boston University 590 Commonwealth Ave. Room 213 Boston, MA 02215 US Office: (617) 353-2619 Email: raverittbuphy.bu http://physics.bu.edu/averittlab/index.html

Biography

RESEARCH INTERESTS:

CURRENT RESEARCH FOCUS:

Optical Spectroscopy of Complex Materials: Complex materials may be defined as having no dominant energy scale the implication being that the charge, lattice, orbital, and spin degrees of freedom conspire to determine their functional, and often emergent, properties. This leads to rich macroscopic and mesoscopic behavior with examples including colossal magnetoresistance, superconductivity, multiferroicity, and electronic phase separation. Furthermore, advances in the synthesis, growth, and integration of nanomaterials make possible the design of nanoscale complex materials inspired by their bulk counterparts. Optical spectroscopy is an important tool to interrogate complexity in materials, naturally complementing techniques such as angle-resolved photoemission or inelastic neutron scattering.

In particular, the beauty of optical studies of condensed phases is the breadth of applicability. Spectral coverage from approximately 0.001 – 4.0 eV is especially important since many relevant excitations lie in this range.

Tetrahertz Metamaterials: The initial impetus driving metamaterials research was the realization and demonstration that a negative refractive index could be obtained by creating patterned subwavelength composites consisting of highly conducting metals such as gold or copper where the effective permittivity and effective permeability are independently specified. Additionally, metamaterials allow for tailoring the impedance in a manner not easily achieved with naturally occurring materials. This newfound approach to engineering the optical properties of materials offers unprecedented opportunities to realize novel electromagnetic responses from the microwave through the visible. This includes cloaks, concentrators, modulators, with many more examples certain to be discovered in the coming years.

Our work in this area is focused on creating novel metamaterial composites which are resonant at far-infrared, or terahertz (THz) frequencies. We are investigating metamaterials at THz frequencies for two main reasons.

IN THE NEWS:

Professor Richard Averitt has received a DARPA Young Faculty Award for his proposal “Metamaterial Enhanced MEMS for Terahertz Technology”. The Young Faculty Award program is designed to seek out ideas from non-tenured faculty with an emphasis on ideas that are innovative, speculative, and high-risk. DARPA’s Microsystems Technology Office sponsors the program.

Journal Articles

20.) X. G. Peralta, M. C. Wanke, C. L. Arrington, J. D. Williams, I. Brener, A. C. Strikwerda, R. Averitt, W. J. Padilla, E. Smirnova, A. J. Taylor, and J. F. O'Hara, "Large-area metamaterials on thin membranes for multilayer and curved applications at terahertz and higher frequencies," Applied Physics Letters, Vol. 94, 24 April 2009

19.) H. Chen, W. J. Padilla, M. J. Cich, A. K. Azad, R. Averitt, and A. J. Taylor, "A metamaterial solid-state terahertz phase modulator," Nature Photonics, Vol. 16, No. 11, 22 February 2009, pp. 7641-7648

18.) V. K. Thorsmolle, R. Averitt, J. Demsar, D. L. Smith, S. Tretiak, R. L. Martin, X. Chi, B. K. Crone, A. P. Ramirez, and A. J. Taylor, "Morphology Effectively Controls Singlet-Triplet Exciton Relaxation and Charge Transport in Organic Semiconductors," Physical Review Letters, Vol. 102, January 2009, pp. 017401

17.) A. C. Strikwerda, K. Fan, H. Tao, D. V. Pilon, X. Zhang, and R. Averitt, "Comparison of birefringent electric split-ring resonator and meanderline structures as quarter-wave plates at terahertz frequencies," Optics Express, Vol. 17, No. 1, January 2009, pp. 136-149

16.) V. H. Whitley, D. E. Hooks, K. J. Ramos, J. F. O'Hara, A. K. Azad, A. J. Taylor, J. Barber, and R. Averitt, "Polarization orientation dependence of the far infrared spectra of oriented single crystals of 1,3,5-trinitro-S-triazine (RDX) using terahertz time-domain spectroscopy," Analytical and Bioanalytical Chemistry, Vol. 395, 2009, pp. 315-322

15.) H. Tao, C. M. Bingham, A. C. Strikwerda, D. V. Pilon, D. B. Shrekenhamer, N. I. Landy, K. Fan, X. Zhang, W. J. Padilla, and R. Averitt, "Highly flexible wide angle of incidence terahertz metamaterial absorber: Design, fabrication, and characterization," Physical Review B, Vol. 78, No. 24, 19 December 2008

14.) D. Talbayev, A. LaForge, S. A. Trugman, N. Hur, A. J. Taylor, R. Averitt, and D. N. Basov, "Magnetic Exchange Interaction between Rare-Earth and Mn Ions in Multiferroic Hexagonal Manganites," Physical Review Letters, Vol. 101, December 2008, pp. 247601

13.) C. M. Bingham, H. Tao, X. Liu, R. Averitt, X. Zhang, and W. J. Padilla, "Planar wallpaper group metamaterials for novel terahertz applications," Optics Express, Vol. 16, No. 23, November 2008, pp. 18565-18575

12.) D. Talbayev, S. A. Trugman, A. V. Balatsky, T. Kimura, A. J. Taylor, and R. Averitt, "Detection of Coherent Magnons via Ultrafast Pump-Probe Reflectance Spectroscopy in Multiferroic Ba0.6Sr1.4Zn2Fe12O22," Physical Review Letters, Vol. 101, August 2008, pp. 097603

11.) H. Chen, J. F. O'Hara, A. K. Azad, A. J. Taylor, R. Averitt, D. B. Shrekenhamer, and W. J. Padilla, "Experimental demonstration of frequency-agile terahertz metamaterials," Nature Photonics, Vol. 2, May 2008, pp. 295-298

10.) H. Chen, H. Lu, A. K. Azad, R. Averitt, A. C. Gossard, S. A. Trugman, J. F. O'Hara, and A. J. Taylor, "Electronic control of extraordinary terahertz transmission through subwavelength metal hole arrays," Optics Express, Vol. 16, No. 11, May 2008, pp. 7641-7648

9.) H. Tao, N. I. Landy, C. M. Bingham, X. Zhang, R. Averitt, and W. J. Padilla, "A metamaterial absorber for the terahertz regime: Design, fabrication and characterization," Optics Express, Vol. 16, No. 10, May 2008, pp. 7181-7188

8.) B. Yellampalle, E. E. Chia, K. Kim, A. J. Taylor, and R. Averitt, "Three envelope approach for ultrafast pulse characterization in a pump-probe experiment," Applied Physics Letters, Vol. 92, No. 6, February 2008, pp. 061111

7.) A. K. Azad, R. P. Prasankumar, D. Talbayev, A. J. Taylor, R. Averitt, J. M. Zide, H. Lu, A. C. Gossard, and J. F. O'Hara, "Carrier dynamics in InGaAs with embedded ErAs nanoislands," Applied Physics Letters, Vol. 93, 2008, pp. 121108

6.) H. Tao, R. Averitt, A. C. Strikwerda, K. Fan, C. M. Bingham, W. J. Padilla, and X. Zhang, "Terahertz metamaterials on free-standing highly-flexible polyimide substrates," Journal of Physics D: Applied Physics, Vol. 41, 2008, pp. 232004

5.) H. Chen, S. Palit, T. Tyler, C. M. Bingham, J. M. Zide, J. F. O'Hara, D. R. Smith, A. C. Gossard, R. Averitt, W. J. Padilla, N. M. Jokerst, and A. J. Taylor, "Hybrid metamaterials enable fast electrical modulation of freely propagating terahertz waves," Applied Physics Letters, Vol. 93, 2008, pp. 091117

4.) R. P. Prasankumar, H. J. Lee, H. Okamura, H. Imai, Y. Shimakawa, Y. Kubo, S. Zvyagin, K. Kamenev, G. Balkrishnan, D. M. Paul, S. A. Trugman, A. J. Taylor, and R. Averitt, "Probing nanoscale inhomogeneities in transition metal oxides with ultrafast mid-infrared spectroscopy," Physica B, Vol. 403, 2008, pp. 1401-1403

3.) H. Chen, W. J. Padilla, J. M. Zide, S. R. Bank, A. C. Gossard, A. J. Taylor, and R. Averitt, "Ultrafast optical switching of terahertz metamaterials fabricated on ErAs/GaAs nanoisland superlattices," Optics Letters, Vol. 32, No. 12, 15 June 2007, pp. 1620-1622

2.) J. F. O'Hara, E. Smirnova, H. Chen, A. J. Taylor, R. Averitt, C. Highstrete, M. Lee, and W. J. Padilla, "Properties of planar electric metamaterials for novel terahertz applications," Journal of Nanoelectronics and Optoelectronics, Vol. 2, April 2007, pp. 90-95

1.) H. Chen, J. F. O'Hara, A. J. Taylor, R. Averitt, C. Highstrete, M. Lee, and W. J. Padilla, "Complementary planar terahertz metamaterials," Optics Express, Vol. 15, No. 3, February 2007, pp. 1084-1095

Conference Papers

2.) H. Tao, A. C. Strikwerda, C. M. Bingham, W. J. Padilla, X. Zhang, and R. Averitt, "Dynamical Control of Terahertz Metamaterial Resonance Response Using Bimaterial Cantilevers," PIERS 2008 Cambridge, Proceedings, 2-6 July 2008

1.) H. Tao, N. I. Landy, K. Fan, A. C. Strikwerda, W. J. Padilla, R. Averitt, and X. Zhang, "Flexible Terahertz Metamaterials: Towards a Terahertz Metamaterial Invisible Cloak," IEEE International Electron Devices Meeting, 2008, pp. 283-286