MRS Spring Meeting:Materials and Material Structures Enabling Terahertz Technology

April 9 - 13, 2007
San Francisco, California

Abstract Submission Guidelines

The terahertz (THz) portion of the frequency spectrum (0.3-10 THz) has attracted interest for various potential applications such as hidden weapons discovery, checking personnel and packages for guns and explosives, chemical and biological detection, and even communications. However, the spectral region has been underutilized because of the inadequacy of THz sources, detectors, and components that are in turn limited by materials. This symposium intends to focus on the latest advances in materials that will enable the development of the terahertz region of the spectrum. The symposium is open to electronic and optical THz-producing techniques. Materials work in growth (bulk, epi, and engineered), characterization (spectroscopy, loss, dielectric studies, etc.), and devices (including vacuum electronics) will be welcomed, but not limited to semiconductors, polymers, biological, chemical, gas, engineered, negative index, molecular, nanotubes, and other materials.

The proposed topics include, but are not limited to:

* Materials for THz sources
* Materials for THz detectors
* Materials for THz components (i.e., modulators, lenses, mirrors, transmission lines, etc.)
* THz spectroscopy of materials (molecular, organic, and inorganic)
* Ultrafast chemistry and physics as it relates to THz
* Material properties at THz frequencies
* Negative Index and other novel materials
* Novel devices for THz applications

Tutorial

A tutorial complementing this symposium is tentatively planned. Further information will be included in the program that will be available in January.

Invited Speakers

Invited speakers include: Mark Allen (Physical Sciences Inc.), Martyn Chamberlain (Teranova), Jim Dayton (Genovac), Yujie Ding (Lehigh Univ.), Martin Dressel (Univ. of Stuttgart, Germany), Nader Enhgeta (Univ. of Pennsylvania), J�r�me Faist (Univ. of Neuch�tel, Switzerland), Tatiana Globus (Univ. of Virginia), Art Gossard (Univ. of California-Santa Barbara), Daniel Mittleman (Rice Univ.), Jorge Seminario (Texas A&M Univ.), Hong Zhang (Northrop/Grumman), and Xi-Cheng Zhang (Rennselaer Polytechnic Inst.).

Symposium Organizers

* Ed Stutz
Air Force Research Laboratory
Materials and Manufacturing Directorate
Rm. 253
3005 Hobson Way
Wright-Patterson AFB, OH 45433-7707
Tel 937-255-9889
Fax 937-255-4913
charles.stutz@wpafb.af.mil

* Ingrid Wilke
Rensselaer Polytechnic Institute
Dept. of Physics
Applied Physics and Astronomy
110 8th St.
Troy, NY 12180-3590
Tel 518-276-6318
Fax 518-276-6680
wilkei@rpi.edu

* Kenneth Kreischer
Northrop Grumman Corporation
Vacuum Electronics Technology
MS H6402
600 Hicks Rd.
Rolling Meadows, IL 60008
Tel 847-259-9600 x-4544
Fax 847-506-7923
kenneth.kreischer@ngc.com

* Qing Hu
Massachusetts Institute of Technology
Rm. 36-465
77 Massachusetts Ave.
Cambridge, MA 02139
Tel 617-253-1573
Fax 617-253-1301
qhu@mit.edu

For more information:
see the Conference Website.

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Terahertz Applications Symposium

2007 SURA Terahertz Applications Symposium

June 6-8, 2007 ~ Washington, DC

Speakers Include:

Confirmed: Don Arnone, TeraView ~ Jill McQuade, Air Force Research Lab ~ Gwyn Williams, Jefferson Lab ~ X.C. Zhang, RPI

Tentative: Dan Mittleman, Rice ~ Martyn Chamberlain, TeraNova

Invited: Claes Bergstedt, ThruVision ~ Luiz Franca-Neto, IEEE ~ Carlo Kosik-Williams, Corning ~ Tom Lee, Standford ~ Eric Mueller, Coherent ~ Mark Rosker, DARPA ~ Steve Williamson, Picomet

For more information
see the Symposium Website.

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Most Cited THz Papers (from thznetwork.org)

The most frequently cited papers in the field of terahertz science and technology. As measured by the number of citations reported in the Web of Science database, here is a list of the most frequently cited terahertz papers from each year since 1990.

1990 Far-infrared time-domain spectroscopy with terahertz beams of dielectrics and semiconductors, D. Grischkowsky, Soren Keiding, Martin van Exter, and Ch. Fattinger, J. Opt. Soc. Am. B, 7, 2006-2015 (1990).

1991 Dynamic conductivity and coherence peak in YBa2Cu3O7 superconductors, Martin C. Nuss, P. M. Mankiewich, M. L. O’Malley, E. H. Westerwick and Peter B. Littlewood, Phys. Rev. Lett., 66, 3305-3308 (1991).

1992 Coherent submillimeter-wave emission from charge oscillations in a double-well potential, Hartmut G. Roskos, Martin C. Nuss, Jagdeep Shah, Karl Leo, David A. B. Miller, A. Mark Fox, Stefan Schmitt-Rink, and Klaus Köhler, Phys. Rev. Lett., 68, 2216-2219 (1992).

1993 Coherent submillimeter-wave emission from Bloch oscillations in a semiconductor superlattice, Christian Waschke, Hartmut G. Roskos, Ralf Schwedler, Karl Leo, Heinrich Kurz and Klaus Köhler, Phys. Rev. Lett., 70, 3319-3322 (1993).

1994 Coherent Electric-Field Effects in Semiconductors, T. Meier, G. von Plessen, P. Thomas, and S. W. Koch, Phys. Rev. Lett., 73, 902-905 (1994).

1995 Imaging with terahertz waves, B. B. Hu and M. C. Nuss, Opt. Lett., 20, 1716-1718 (1995).

1996 Characterization of a cage form of the water hexamer, K. Liu, M. G. Brown, C. Carter, R. J. Saykally, J. K. Gregory, and D. C. Clary, Nature, 381, 501-503 (1996).

1997 Free-space electro-optics sampling of mid-infrared pulses, Q. Wu and X.-C. Zhang, Appl. Phys. Lett., 71, 1285-1286 (1997).

1998 High average-power THz radiation from femtosecond laser-irradiated InAs in a magnetic field and its elliptical polarization characteristics, Nobuhiko Sarukura, Hideyuki Ohtake, Shinji Izumida, and Zhenlin Liu, J. Appl. Phys., 84, 654-656 (1998).

1999 Recent advances in terahertz imaging, D. M. Mittleman, M. Gupta, R. Neelamani, R. G. Baraniuk, J. V. Rudd, and M. Koch, Appl. Phys. B, 68, 1085-1094 (1999).

2000 Pulsed terahertz spectroscopy of DNA, bovine serum albumin and collagen between 0.1 and 2.0 THz, A. G. Markelz, A. Roitberg, and E. J. Heilweil, Chem. Phys. Lett., 320, 42-48 (2000).

2001 Coherent manipulation of semiconductor quantum bits with terahertz radiation, B. E. Cole, J. B. Williams, B. T. King, M. S. Sherwin and C. R. Stanley, Nature, 410, 60-63 (2001).

2002 Terahertz semiconductor-heterostructure laser, Rüdeger Köhler, Alessandro Tredicucci, Fabio Beltram, Harvey E. Beere, Edmund H. Linfield, A. Giles Davies, David A. Ritchie, Rita C. Iotti and Fausto Rossi, Nature, 417, 156-159 (2002).

2003 3.4-THz quantum cascade laser based on longitudinal-optical-phonon scattering for depopulation, Benjamin S. Williams, Hans Callebaut, Sushil Kumar, Qing Hu and John L. Reno, Appl. Phys. Lett., 82, 1015-1017 (2003).

2004 Terahertz magnetic response from artificial materials, T. J. Yen, W. J. Padilla, N. Fang, D. C. Vier, D. R. Smith, J. B. Pendry, D. N. Basov, and X. Zhang, Science, 303, 1494-1496 (2004).

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Near-infrared response for laser etched silicon

A microstructured silicon photodetector that exhibits a photoresponse at 1.31 and 1.55 microns could inspire a host of specialized imaging applications.
Scientists are using the same microstructuring approach that enhances the efficiency of silicon solar cells to widen the spectral response of photodetectors. (Appl. Phys. Lett. 89 033506)
"The challenges lay in understanding the material's physical properties and how they can be controlled and used to improve device performance," Jim Carey of Harvard University, US, told optics.org.

Conventionally, silicon is transparent to wavelengths longer than 1 µm, which makes it unsuitable for many near-infrared applications. However, the researchers have found a way of modifying the material's band-gap to make it absorb at longer wavelengths.
Using a Ti:sapphire laser, Carey and his colleagues irradiate n-doped Si wafers with a 1 kHz train of 100 fs pulses in an sulfur-rich atmosphere to generate a surface covered with 2-3 micron-sized structures. According to the team, the laser causes ablation and melting of the silicon surface, which evolves and interacts with the gas before re-solidifying with an altered morphology.

The detector's microstructured surface encourages multiple reflections, which promote the absorption of light. However, this is only part of the picture. "It is a combination of increased absorption in the infrared and large gain that leads to the extension of the operating wavelength," said Carey. "The incorporation of large amounts of sulfur during laser irradiation is responsible for significant absorption beyond 1100 nm."
Photodetectors made from the textured silicon were found to have a responsitivity of 92 A/W at 850 nm and 119 A/W at 980 nm (3V reverse bias in both cases). What's more, the devices continued to exhibit a photoresponse at 1.31 and 1.55 µm.
The group, which also includes scientists from the University of Texas and the University of Virginia, both US, is now looking to commercialize its technology. Carey expects that the first big market will be in specialized imaging applications such as security and surveillance. He thinks that it is unlikely that devices will make their way into consumer items such as camera phones. "Margins are too low and the end customer doesn't care enough about the infrared to drive a premium," he commented.

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Wavelength converter wins award for Lawrence Livermore Lab

Lawrence Livermore National Laboratory, Livermore, CA, US, has been awarded an "R&D 100" award for developing a high average power wavelength conversion device that can change the color of laser light.

The photo shows a yttrium calcium oxyborate (YCOB) crystalline plate in an optical mount, foreground). [Invisible] Infrared light enters from the right and passes through the YCOB crystal. Some of the infrared light is wavelength shifted (frequency converted) to the visible (green), and the second harmonic or green light emerges from the crystalline plate on the left before hitting an energy detector in the background.LLNL laser scientists say that the converter will permit large aperture, high average power lasers to operate at half the wavelength of the laser crystal's natural emission wavelength.
The device, which is based on the YCOB crystal, was developed in tandem with Crystal Photonics, a company based in Sanford, FL, US.
"Many of today's lasers operate in the infrared portion of the spectrum - a color or wavelength that is not the most efficient for some applications," commented an LLNL spokesman. "Both the YCOB crystal's ability to handle heat and its ease of growing could permit some of these lasers to operate more efficiently at the shorter wavelength."
As examples, ceramics and plastics could be more efficiently machined with ultraviolet light, and copper metal for electronic circuit boards could be more efficiently cut with green light.
The LLNL YCOB wavelength converter holds the current world record for an average-power, high-pulse-energy laser at 225 W of 523.5 nm light, at a repetition rate of 10 Hz and 22.5 J per pulse. One YCOB crystal can replace eight optical components.The conversion device and YCOB crystal were developed by LLNL employees in the National Ignition Facility and Engineering directorates.
The development of the YCOB crystal is a direct consequence of LDRD funding since 1997. This money was awarded to study the use of a solid state laser as a potential replacement for the copper vapor lasers in the Atomic Vapor Laser Isotope Separation program. The funding allowed researchers to study new nonlinear optical crystals.

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