Perfect lenses in focus

摘要

In 2000, Pendry showed1 that a slab of material that bends light at a negative angle can work as a lens with the ability to resolve details much smaller than the wavelength of light. This is due to the fact that, unlike conventional lenses, which refract light at a positive angle (Fig. 1), this device transfers not only the propagating (long-range) waves of light from an object to its image, but also the objects evanescent waves - short-range light that carries smallest-scale information about the object. However, such a perfect lens, although based on a neat idea, has some serious drawbacks. For example, it turns out2 that, for fundamental reasons, negative refraction is always connected with light absorption, and such absorption destroys the super-resolution ability of the lens. Moreover, perfect lenses based on negative refraction are difficult to manufacture and can work only in narrow bands of the electromagnetic spectrum.