Angular momentum (AM), one of the most basic physical properties of light, has attracted great interest of the scientific community due to its significant values in high-capacity optical communication.
To realize AM multiplexing and demultiplexing, the methods based on metallic metasurface are proposed, which suffers from huge Ohmic losses. Besides, additional coupling elements are necessary for coupling the output light into single-mode waveguides.
Here, an efficient and focused AM multiplexing and demultiplexing system based on dielectric metasurfaces are proposed and investigated by a research team led by Prof. Dr. WANG Guoxi from Xi'an Institute of Optics and Precision Mechanics (XIOPM) of the Chinese Academy of Sciences (CAS). Employing the off-axis technique and spin photonic Hall effect, the orbital angular momentum (OAM) and spin angular momentum (SAM) multiplexing/demultiplexing can be achieved.
Illustration of the AM multiplexing and demultiplexing based on a dielectric metasurface. (Image by XIOPM)
A 10-channel AM multiplexing/ demultiplexing system based on the proposed method is demonstrated. The demultiplexing efficiencies for all AM stats are above 8% and the maximum crosstalk among all AM states is ？12.8 dB, which exhibits an excellent performance of the proposed metasurface for the AM demultiplexing.
Furthermore, the output light is focused at the focal plane, which can be directly coupled into the single-mode waveguides and improve the compactness of the system. The proposed method provides an effective way for AM multiplexing and demultiplexing, which possess a crucial potential for high-capacity optical communication applications.
(Original research article “Advanced Optical Materials” (2020) https://doi.org/10.1002/adom.201901666)
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