Materials Science

Idling Away Losses

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Science  07 Jul 2006:
Vol. 313, Issue 5783, pp. 20
DOI: 10.1126/science.313.5783.20b

The development of metamaterials, in which electromagnetic behavior can be tuned by design, has already yielded such interesting effects as negative refraction and superlensing (subwavelength focusing). Progress in the fabrication of subwavelength-featured structures has carried these effects from the microwave regime through the terahertz and into the infrared region. However, one severe problem in the materials has been high signal losses, particularly due to absorption. Among the ideas floated to counter these losses is incorporating a gain medium into the design, though a major drawback to this approach is that it would indiscriminately amplify noise in addition to the desired signal.

Popov and Shalaev propose an alternative: moving into the nonlinear regime and using optical parametric amplification. Their calculations show that mixing the signal field with an optimally tuned auxiliary electromagnetic pump field should produce an idler field at the difference frequency; this idler would then induce amplification of the signal field through three-wave mixing with the pump, thus compensating for absorption losses precisely at the signal frequency. The challenge now will be to implement these theoretical ideas and thereby achieve the promising applications of the materials. — ISO

Opt. Lett. 31, 2169 (2006).

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