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February 15, 2008

Toward Practical visible light metamaterial Hyperlens and new wireless metamaterial breakthroughs


Xiang Zhang (on of the makers of the UV light hyperlens: Theoretically, the biggest obstacle [to progress on visible light hyperlens] is the inevitable loss in the metamaterials. This means that -- to obtain reasonable transmission -- the hyperlens can't be very bulky; this will limit the magnification and imaging area …. Low loss metals and high refractive index dielectrics will greatly boost this field but are extremely hard to find."

Pendry agrees that loss is a major issue for optical metamaterials. "Typically we might use highly conducting metals such as copper or silver which work just fine until we try to use them at the highest frequencies where they become lossy. We need the help of materials scientists to develop new alloys with lower losses."


At the end of 2007, Princeton researchers reported they had developed an optically-thick low-loss negative-index material consisting of alternating layers of highly doped InGaAs and AlInAs -- no metals. Interestingly, the Princeton material uses an entirely different effect than the others to implement the negative index. The optical properties are created by anisotropy in the material's dielectric response rather than resonances in both the permeability and permittivity of the constituent layers. This gives it an inherent flexibility.

On top of its other advantages, the Princeton metamaterial is the first in a new class not only in terms of mechanism but in its potential to be practically fabricated.


Wireless equipment developers are also starting to realize the potential of using components based on metamaterials. In fact Netgear introduced two new routers that use metamaterial antenna systems—WNR3500 and WNDR3300—at CES 2008.

Rayspan has developed metamaterial-based MIMO antenna arrays exhibiting performance characteristics equivalent to conventional MIMO antenna arrays, yet take up less space.

What essential communications components and subsystems are enabled by metamaterials? Metamaterials technology brings three powerful enabling capabilities: (1) the ability to strongly manipulate the propagation of electromagnetic waves in the confines of small structures, (2) simultaneous support of multiple RF functions, and (3) the freedom to precisely determine a broad set of parameters which include operating frequency and bandwidth; positive, negative and zero phase offsets; constant phase propagation; and matching conditions and number and positioning of ports.

These capabilities make possible a broad range of metamaterial components and subsystems:

- Physically small, but electrically large components such as compact antennas sized on the order of a signal’s wavelength/10 while providing performance equal to or better than conventional antennas sized wavelength/2 - a five times size reduction.

- Broadband matching circuits, phase-shifting components and transmission lines which preserve phase linearity over frequency ranges five to ten times greater than those provided by conventional counterparts.

- Multi-band components whose frequencies of operation can be tailored to specific applications and are not limited to harmonic frequency multiples.


FURTHER READING
metamaterials and superlens

Metamaterials background and superlens



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