Abstract-Terahertz Metamaterials for Linear Polarization Conversion and Anomalous Refraction

1. 
   

1. Nathaniel K. Grady¹, 
2. Jane E. Heyes¹, 
3. Dibakar Roy Chowdhury¹, 
4. Yong Zeng², 
5. Matthew T. Reiten¹, 
6. Abul K. Azad¹,
7. Antoinette J. Taylor¹, 
8. Diego A. R. Dalvit², 
9. Hou-Tong Chen¹,*

+Author Affiliations

http://www.sciencemag.org/content/early/2013/05/15/science.1235399.abstract
Polarization is one of the basic properties of electromagnetic waves conveying valuable information in signal transmission and sensitive measurements. Conventional methods for advanced polarization control impose demanding requirements on material properties and attain only limited performance. Here, we demonstrate ultrathin, broadband, and highly efficient metamaterial-based terahertz polarization converters that are capable of rotating a linear polarization state into its orthogonal one. Based on these results, we create metamaterial structures capable of realizing near-perfect anomalous refraction. Our work opens new opportunities for creating high-performance photonic devices and enables emergent metamaterial functionalities for applications in the technologically difficult terahertz frequency regime.

Abstract-Active control of electromagnetically induced transparency analogue in terahertz metamaterials

http://www.nature.com/ncomms/journal/v3/n10/full/ncomms2153.html

Jianqiang Gu, Ranjan Singh, Xiaojun Liu, Xueqian Zhang, Yingfang Ma,, Shuang Zhang,  Stefan A. Maier, Zhen Tian, Abul K. Azad,, Hou-Tong Chen,Antoinette J. Taylor,Jiaguang Han, Weili Zhang

Recently reported metamaterial analogues of electromagnetically induced transparency enable a unique route to endow classical optical structures with aspects of quantum optical systems. This method opens up many fascinating prospects on novel optical components, such as slow light units, highly sensitive sensors and nonlinear devices. In particular, optical control of electromagnetically induced transparency in metamaterials promises essential application opportunities in optical networks and terahertz communications. Here we present active optical control of metamaterial-induced transparency through active tuning of the dark mode. By integrating photoconductive silicon into the metamaterial unit cell, a giant switching of the transparency window occurs under excitation of ultrafast optical pulses, allowing for an optically tunable group delay of the terahertz light. This work opens up the possibility for designing novel chip-scale ultrafast devices that would find utility in optical buffering and terahertz active filtering

Abstract: Dynamically reconfigurable terahertz metamaterial through photo-doped semiconductor

http://apl.aip.org/resource/1/applab/v99/i23/p231101_s1?isAuthorized=no

Dibakar Roy Chowdhury¹, Ranjan Singh¹, John F. O’Hara^1,2, Hou-Tong Chen¹, Antoinette J. Taylor¹, and Abul K. Azad¹

¹Center for Integrated Nanotechnologies, Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
²School of Electrical and Computer Engineering, Oklahoma State University, Stillwater, Oklahoma 74078, USA

We demonstrate reconfigurable terahertz metamaterial (MM) in which constituent resonators can be switched from split-ring resonators (SRRs) to closed-ring resonators via optical excitation of silicon islands strategically placed in the split gap. Both the fundamental and the third-order resonance modes experience monotonic damping due to increasing conductive losses in the photo-doped silicon region. More importantly, increasing the optical fluence (>200 μJ/cm²) results in the excitation of the second-order resonance mode, which is otherwise forbidden in a split-ring resonator for the incidence polarization in our experiments. Such dynamical control of metamaterial resonances could be implemented in active terahertz devices to achieve additional functionalities.

© 2011 American Institute of Physics

Active Terahertz Metamaterials

MY NOTE: I DON'T TYPICALLY POST ABSTRACTS RELATING TO  THz, FROM THE NET. I JUST CAME ACROSS THIS ONE, AND THE BRIEF DESCRIPTION HELPED ME BETTER "TIE" THE CONNECTION BETWEEN METAMATERIALS AND TERAHERTZ, AND MAYBE IT WILL BE USEFUL TO SOME OF YOU AS WELL.

Author:

  Antoinette Taylor
    (Los Alamos National Laboratory)

In recent years terahertz technology has become an optimistic candidate for numerous sensing, imaging, and diagnostic applications. Nevertheless, THz technology still suffers from a deficiency in high-power sources, efficient detectors, and other functional devices ubiquitous in neighboring microwave and infrared frequency bands, such as amplifiers, modulators, and switches. One of the greatest obstacles in this progress is the lack of materials that naturally respond well to THz radiation. The potential of metamaterials for THz applications originates from their resonant electromagnetic response, which significantly enhances their interaction with THz radiation. Thus, metamaterials offer a route towards helping to fill the so-called ``THz gap''. Here, we present a series of novel THz metamaterials. Importantly, the critical dependence of the resonant response on the supporting substrate and/or the fabricated structure enables the creation of active THz metamaterial devices. We show that the resonant response can be controlled using optical or electrical excitation and thermal tuning, enabling efficient THz devices which will be of importance for advancing numerous real world THz applications.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2011.MAR.D32.7

Abstract ID: BAPS.2011.MAR.D32.7

Abstract: D32.00007 : Active Terahertz Metamaterials

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