Orbital Light Study Promotes New Applications for Light-Capturing Materials

There is a tiny crystalline material that traps light inside and becomes a closed, periodical orbiting light that is attracting more and more attention from scientists. Recently, scientists at the University of California, San Diego have elaborated on the performance of captured light in nanocrystals. Related papers were published in the Nano Express.

According to a recent report by the Physicist Organization Network, Michael Vögler, a professor of physics at the university, and colleagues demonstrated last year that light can be stored in nanocrystalline particles called hexagonal boron nitride. In hexagonal boron nitride crystals, boron and nitrogen atoms form a hexagonal layered lattice that can bend electromagnetic energy in an unusual way.

Light particles, also called polarized phonons, do not obey the standard reflection law when they bounce in crystal grains, and their motion is not random. According to the research, polarized phonon rays will be emitted along the atomic structure of the material along a fixed angular path, leading to interesting resonances. VÖgler said: "In most cases, the trajectories of the captured polar phonon rays are coiled and convoluted, but at a certain frequency, they will become simple closed circular orbits."

When the trajectory is closed, there will be a "hot spot" area where the electric field is greatly enhanced. The team found that these "hot spots" form fine geometric patterns inside the sphere-like crystal grains.

The researchers also analyzed how light was trapped inside the material. It was found that the pattern and the specific frequency were determined not by the size of the material sphere but by its shape. The analysis also shows that there is a parameter that determines the fixed angle at which polarized phonon rays exit the sphere.

These analyses provided a theoretical explanation for the light captured by the research team in its early observations. Vögler and colleagues say that experiments can be used to prove their prediction of orbital light. At present, they are exploring the practical use of hexagonal boron nitride and hope to use it to manipulate light. This principle of action helps guide practical applications such as nanoresonators for high resolution color filtering and spectral imaging, hyper-lenses for sub-diffraction imaging, and infrared photon sources. (Reporter Chang Lijun)