to the Website of a Multidisciplina- ry University Research Initiative (MURI) Project "Tunable and Re- configurable Optical Negative-Index Materials with Low Losses".
The focus of this project is NIMs - Negative-Index Materials - a novel class of engineered materials with very unusual and potentially very valuable optical properties. The most surprising characteristic of these materials is their negative refractive index, hence the name - NIMs.
The refractive index gives the factor by which the phase velocity of electromagnetic waves propa- gating in a material is decreased relative to its magnitude in vacuum. One of the manifestations of nega- tivity of the refractive index of NIMs is the fact that the phase velocity of electromagnetic waves in them is directed against the flow of energy.
There are no naturally-occurring NIMs, as far as we know, but certain specially designed artificial materials (metamaterials: see an example in the column on the right) can possess the property of negative refraction. Metamaterials offer unique physical properties and can enable functionality of devices based on them unattainable with naturally-existing materials.
In this project, we will study NIMs for the Optical frequency range (ONIMs), and we will focus on eli- minating light energy losses in ONIMs and developing novel ONIM-based applications.
The material losses will be over- come by compensation with ampli- fication provided by gain inclusions, elimination by using passive low-loss components, or a combination of both.
New applications are exemplified by optical nanoscale lithography, imaging, and sensing utilizing an ONIM-based tunable and recon- figurable superlens.
Nanorod: a Negative-Index Material
An array of pairs of parallel gold nano- rods has a negative refractive index in the optical range (at λ~1.5μm ).
For normally incident light (k, in the figure above) with the electric field (E) polarized along the rods and the mag- netic field (H) perpendicular to the pair, the electric and magnetic responses both can experience resonant beha- vior.
The excitation of plasmon resonances for both the electric and the magnetic light components results in the reso- nant behavior of the refractive index, which can become negative above the resonance, as the figure above shows.
Field-emission scanning electron micro- scope images of a portion of the expe- rimental sample and a closer view of a single pair of rods.
APS NEWS, May 2007: "... at the APS meeting in Denver, Purdue University’s Vladimir Shalaev reported on a new record-setting metamaterial that might be ideal for so-called 'superlensing': a process in which a thin flat panel of the metamaterial would be able to image an object at a spatial resolution better than the wave-length of the illuminating light ..." learn more...
Science Daily, April 2, 2007: "Researchers using nanotech-nology have taken a step toward creating an 'optical cloaking' device that could render objects invisible by guiding light around anything placed inside this 'cloak.' The research is based at the Birck Nanotechnology Center at Purdue's Discovery Park ..." learn more...
The Nanorod Material developed by the Prof. Shalaev's group has been named a winner in the se- cond annual Nanotech Briefs Nano 50(TM) Awards in the Technology category.
Presented by the Nanotech Briefs magazine – the monthly digital publication from the publishers of NASA Tech Briefs – the Nano 50 recognizes the top 50 technolo- gies, products, and innovators that have significantly impacted, or are expected to impact, the state of the art in nanotechnology. learn more...
An OSA Topical Meeting "Photonic Metamaterials: from Random to Periodic" (co-chiars V. Shalaev, Purdue, and A. Genack, Queens College) has taken place in the Bahamas June 5-8, 2006.
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