Over the last few years, scientists have continued to explore "one-way" light, which refers to a light beam that only materializes in one direction. This effect is created using optical diodes in a similar manner that standard diodes are used in an electric circuit to prevent the current from travelling in a certain direction. Now, researchers from Nanjing University have built upon this previous research to theoretically show that "one-way" light beams in photonic crystals can be shaped into various trajectories using a gradient magnetic field. The finding could help scientists further understand integrated photonic circuits, where beams of light are the root of their operations.
Although light beams typically broaden as they propagate when in photonic crystals, the researchers show that these crystals can be altered so that the light stays highly focused and self-collimated, preventing the broadening process. Furthermore, they found that applying a gradient magnetic field to the crystal after this alteration can cause the self-collimated beam to change its direction over time.
"First, we found the novel effect of self-collimation of a unidirectional electromagnetic wave beam in gyrotropic photonic crystals," said Rui-xin Wu, co-author of the study, in a press release. "Second, the more interesting part is that we can steer the wave beam trajectory through the distribution of a bias magnetic field, providing a flexible means to control the wave beam propagation."
The researchers plan to continue their study into these "one-way" beams and better understand their underlying mechanisms. Advancements in the field could be used to integrate the beams into a wide variety of applications, including optical communications and invisibility cloaks.
"Another potential application is to hide an object within the photonic crystal," said Wu. "Since the wave path can be bent in a controlled way, we can have the wave beam trajectory go around but not hit the object, so that the object cannot be seen."
The findings were published in the Dec. 16 issue of Applied Physics Letters.
