Andrea Alù

An ordinary piece of semiconductor weakly changes the color of light passing through it. For decades, physicists worked around this limitation by placing the crystal in clever surroundings, but the material itself remained the same. Now researchers have assembled a "sandwich" of alternating thin layers of gallium arsenide and aluminum gallium arsenide.

A river flows in one direction, but a wave on its surface travels in the opposite direction. The same splitting happens in hyperbolic materials: the energy of a light wave and its fronts diverge, preventing a sharp lens from being created.

Quantum computers and sensors operate at microwave frequencies, but transmitting their signals over long distances is conveniently done via optical fibers, which use light.