The new optical isolators—a way to control particle motions on 2-D materials

Researchers have uncovered a new way to control particle motions on 2D materials such as graphene, separating quasiparticles called plasmons into two streams moving in opposite directions without requiring strong magnetic fields.

MIT associate professor of mechanical engineering Nicholas X. Fang, recent PhD graduate Anshuman Kumar, and four other researchers from the University of Wisconsin at Milwaukee, Hong Kong Polytechnic University, and the University of Minnesota conducted the research.

The separated flows had previously been accomplished by other researchers but the separation required the use of powerful magnetic fields, something that may not be practical in real life applications.

This research group discovered a process that shies away from needing magnetic fields, but instead uses optical effects, generated with beams of circularly polarized light.

When the light is shone on graphene ribbons it causes electrons in that material to separate into two distinct valleys. Another beam of light can be used to detect transmission to measure the effects.

This is very useful and exciting news, especially for those using photonic systems that require optical isolators. Optical isolators keep beams of light from causing interference, which can happen if the beams of light reflect back to the source. Optical isolators are useful and much needed in many cases, but can be bulky.

With the new particle motion discovery, optical isolation can be done without a magnetic field, on a chip scale. This advancement could lead to lots of new technology that is less cumbersome, and more immune to interference.

While optical isolators have their place in current technology and may still be needed in various applications in the future, this represents an exciting shift in current technology.

Within the industry, manufacturers and researchers are looking for ways to create smaller, more powerful chips that can last longer and work harder within devices. The new particle motion control technology is such that, were it similarly powered by a magnetic field, it would have to be contained in a research facility due to the strength of magnet required.

The research done by this group points toward a growing interest in technology that is lighter and more portable, which translates to lighter, more portable devices. We may still use optical isolators in other applications, but for companies that want to avoid using strong magnetic fields, this is certainly an exciting discovery.

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