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NEWS: AUGUST 3, 2006 Scientific American Magazine Highlights Zhang Group’s Research
“ … Xiang Zhang’s group at the University of California, Berkeley, independently followed this prescription and demonstrated superresolution in an optical system. … Zhang used a layer of silver about 40 nanometers thick to image 365-nanometer-wavelength light emanating from shaped apertures smaller than the light’s wavelength. Although a silver slab is far from the ideal lens, the silver superlens substantially improved the image resolution, proving the underlying principle of superlensing.” Zhang reported the demonstration of what he called a “Superlens” in the April 2005 Issue of Science, which allows never-before-seen detail by essentially recovering light waves that have traditionally been lost in lenses. "In a regular lens you can transmit only part of the spectrum of the waves," he says. "One type of waves cannot pass through to the image. If you can view the lens made by metamaterial, it has the capability to enhance or amplify this wave ... then the image has a much sharper resolution." Link to Scientific American Article Link to Prof. Zhang’s Science Article Link to Prof. Xiang Zhang's Lab Website
“Left Handed Water” reported for the first time in Nature Materials. Prof. Xiang Zhang’s group has demonstrated the phenomenon of “Left Handed Water” for the first time. Published in the June Issue of Nature Materials, 2006, the discovery hails the arrival of new applications in ultrasonics including acoustic negative refraction and ultrasound superlensing below the diffraction limit. A basic property of any elastic material, the modulus of elasticity, measures the resistance of the material due to an applied force. Akin to electromagnetic parameters, such as the magnetic permeability and the electric permittivity, a material with negative modulus exhibits acoustic waves where energy flows in the opposite direction to the phase of the wave, commonly referred to as a “left handed material”. In their report, Zhang’s group present a new class of ultrasonic metamaterial composed of resonant units that are smaller than the acoustic wavelength. The building blocks are a series of rigid walled cavities, each with a small hole on one side. The resonator is analogous to the effect of inductors and capacitors in electronic circuits: pressure variations in the resonators cause fluid to oscillate in and out of the hole, producing the necessary retardation effects that cause the left handed response. Link to Nature Materials Article Link to Prof. Xiang Zhang's Lab Website
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