Photonic Spin Hall Effect Captured with 2-D Metamaterial
Berkeley Lab researchers obtained the strongest signal yet of the photonic spin Hall effect by engineering a unique two-dimensional metamaterial sheet of gold nanoantennas. The work demonstrates that metamaterials allow control over not only propagation of light but also of circular polarization, results that could have important consequences for information encoding and processing.
Analogous to the electron spin Hall effect, the photonic spin Hall effect is an exceedingly small transfer of spin to orbital angular momentum in light. In the past, researchers have managed to observe the effect only by accumulating signal over many repetitions, or by using highly sophisticated quantum measurements.
Here, researchers obtained a strong photonic spin-Hall measurement using a simple camera by enhancing the naturally weak signal with a specially engineered metamaterial surface. These metasurfaces were constructed from V-shaped gold nanoantennae engineered to generate a linear phase gradient along the x direction. Light passing through the metamaterial exhibited photonic spin Hall effect proportional to the geometry of the nanoantennae.
The strength of the signal measured in these experiments coupled with the simplicity of the experiment suggest the metasurfaces for technological applications, such as photonic devices that could encode more information and provide greater information security than conventional electronic devices.