By Patricia Daukantas
I thought I’d give my readers a quick summary of some of the interesting sessions I’ve been attending at CLEO/QELS and CLEO:Applications.
As you might expect, both terahertz technology and metamaterials are really hot topics right now. Put them together and you get a well-attended session on terahertz metamaterials. Hui Tao, Richard D. Averitt and colleagues at Boston University (U.S.A.) built structurally reconfigurable metamaterials using the techniques of micro-electro-mechanical-systems (MEMS) fabrication.
Basically, the BU team built an array of tiny split-ring resonators (SRRs), 72 x 72 m m in size, with an in-plane periodicity of 100 m m. These things are made of bianisotropic gold-silicon nitride and they tilt up and down like an array of little flaps, thus controlling the beam of terahertz radiation passing through the metamaterial. (Note: Tao recently finished his Ph.D. and is a postdoctoral fellow at Tufts University, also in Massachusetts, U.S.A.)
Also on the topic of metamaterials, a German group led by Benjamin Reinhard of the University of Kaiserslautern studied surface terahertz surface waves on an array of copper SRRs. Their experiment’s unit size was 41 x 41 m m, or about 1/7 of a wavelength at 1 THz, and every sixth row of the array was removed. They modeled the metamaterial as a thin-slab waveguide and found that their experimental (See the May 1 issue of Optics Letters -- vol. 35, p. 1320 -- for more details on their work.)
I always enjoy the Market Focus sessions (PhAST in past years, CLEO:Applications in 2010), and this year’s have been no exception.
At an energy-related session, Corey Dunsky, president of Aeos Consulting Inc. (U.S.A.), made some powerful arguments that lasers can help lower manufacturing costs and improve the conversion efficiency of photovoltaic panels. In one example he offered, single-step laser doping is well-positioned to be the best way of fabricating selective emitters on the surfaces of crystalline silicon solar panels. Andrew Masters, a vice president of Veeco Instruments (U.S.A.), described how his company’s atomic force microscopes can quantify solar cells’ efficiency to within plus-or-minus 0.5 percent.
Another session of Market Focus examined various optical methods for detecting chemical threats and explosives.
Price Kagey of Surface Optics Corp. (U.S.A.) reviewed a whole list of technologies -- laser-induced breakdown spectroscopy, Raman spectroscopy, quantum-cascade-laser-based heating and thermography, broadband heating and emission spectroscopy, and hyperspectral imaging -- and found that all of them came up short in one way or another (cost, eye safety, ease of remote deployment, etc.).
Dan Strellis of Rapiscan Systems Ltd. (United Kingdom) said his company is working with both terahertz and X-ray technologies to develop a scanner specifically for shoes, so that airline passengers wouldn’t have to take off their shoes at security checkpoints. According to Adam Bingham of ICx Technologies (U.S.A.), workable systems for detecting explosives at checkpoints will probably require pairs of systems, one for wide-area scanning and a different kind of detector for zooming in to provide “high-confidence confirmation.”
Today (Thursday in California) is the final day that CLEO’s exhibit hall is open, so I’ll be making a final swing through there -- and getting one last glimpse of the laser history exhibit (more on that shortly). Tonight features the three concurrent CLEO/QELS postdeadline paper sessions.
One thing I’ve forgotten to mention in previous posts is a special LaserFest presentation: reprints of a collection of early quantum-electronics papers from the Soviet Union. It’s titled “Beginning of the Laser Era in the USSR,” and some of the articles have been translated into English for the first time. You can find it on the LaserFest website, Optics InfoBase or
2010-05 May, CLEO/QELS, Lasers, Lasers, CLEO