One-way light beam can be steered in different directions

Over the past few years, scientists have demonstrated the phenomenon of "one-way light," in which a light beam propagates in one direction only. The materials used to achieve this effect can be thought of as optical diodes, in analogy to the diodes used in electric circuits that allow an electric current to travel in one direction while prohibiting it from traveling in the opposite direction. One-way light could play an important role in integrated photonic circuits, which perform operations using beams of light instead of an electric current. Researchers have previously shown that a few different materials, such as photonic crystals and metamaterials, can be used to realize one-way light. These materials typically have some kind of asymmetry that routes light differently depending on which direction the waves are traveling. Building on this research, Qing-Bo Li, et al., from Nanjing University in China have theoretically shown that one-way light beams in photonic crystals can be bent into arbitrary trajectories by applying a gradient magnetic field. Their work is published in a recent issue of Applied Physics Letters.

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