The possibility of compensating absorption in negative-index metamaterials (NIMs) doped by resonant nonlinear-optical centers is shown. The role of quantum interference and the extraordinary properties of four-wave parametric amplification of counterpropagating electromagnetic waves in NIMs are discussed.
All-optical switching from absorption to amplification and wavelength-selective narrowband filtering are shown possible in doped solids based on parametric amplification and quantum interference. The results are discussed in the context of compensation of losses in negative-index metamaterials. Absorption is generally recognized now as one of the most… (More)
Neither flapping and running to take-off nor gliding from heights can be disproved as the assured evolutionary origin of self-powered flight observed in modern vertebrates. Gliding with set wings would utilize available potential energy from gravity but gain little from flapping. Bipedal running, important in avian phylogeny, possibly facilitated the… (More)
With the development of experimental techniques, effective injection and transportation of electrons is proven as a way to obtain polymer light-emitting diodes (PLEDs) with high quantum efficiency. This paper reveals a valid mechanism for the enhancement of quantum efficiency in PLEDs. When an external electric field is applied, the interaction between a… (More)