Twisted optics: Seeing light from a new angle
Researchers have developed a technique to generate miniature light beams that are twisted in orientation, similar in shape to a helix. While such a feat has been achieved on larger scales using bulky devices, the ability to create the same effect on a microscale has remained elusive; tapping into angled light on smaller scales could lead to important advances in telecommunication and information technologies, by increasing the rate of the information transmission. Naturally, light travels linearly, but, when it has greater degrees of freedom, it can be used to store more information than it can store its linear state. Here, Pei Miao and colleagues implemented changes to a micro-ring, a cylinder-like structure that can be used to give light a projection at a particular angle; this in turn guides light waves to travel along the inside of the micro-ring cylinder. However, when light travels in both clockwise and counterclockwise directions, the waves cancel each other out. To overcome this obstacle and make the light unidirectional within the micro-ring, the team added alternating layers of germanium, as well as germanium with cerium. Strategically placed, these layers caused the light to converge on a single point and travel unilaterally through the micro-ring, which the authors confirmed through experiments.
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