We present a method to efficiently multiply or divide the orbital angular momentum (OAM) of light beams using a sequence of two optical elements. The key element is represented by an optical transformation mapping the azimuthal phase gradient of the input OAM beam onto a circular sector. By combining multiple circular-sector transformations into a single optical element, it is possible to multiply the value of the input OAM state by splitting and mapping the phase onto complementary circular sectors. Conversely, by combining multiple inverse transformations, the division of the initial OAM value is achievable by mapping distinct complementary circular sectors of the input beam into an equal number of circular phase gradients. Optical elements have been fabricated in the form of phase-only diffractive optics with high-resolution electron-beam lithography. Optical tests confirm the capability of the multiplier optics to perform integer multiplication of the input OAM, whereas the designed dividers are demonstrated to correctly split up the input beam into a complementary set of OAM beams. These elements can find applications for the multiplicative generation of higher-order OAM modes, optical information processing based on OAM beam transmission, and optical routing/switching in telecom.
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http://dx.doi.org/10.1038/s41377-019-0222-2 | DOI Listing |
Adv Mater
December 2024
Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, Guangdong, 518055, China.
Vectorial metasurface holography, allowing for independent control over the amplitude, phase, and polarization distribution of holographic images enabled by metasurfaces, plays a crucial role in the realm of optical display, optical, and quantum communications. However, previous research on vectorial metasurface holography has typically been restricted to single degree of freedom input and single channel output, thereby demonstrating a very limited modulation capacity. This work presents a novel method to achieve multi-channel vectorial metasurface holography by harnessing spin-orbit-locking vortex beams.
View Article and Find Full Text PDFVortex beams (VBs) have the potential to support high-capacity optical communications. However, a typical VB carries only a single orbital angular momentum (OAM) in space, limiting its high-capacity communication. We propose controllably simultaneous generation of high-quality VB arrays with multiple OAMs, creating the independent multi-channel space in which the OAM mode can be flexibly manipulated at the corresponding spatial location.
View Article and Find Full Text PDFSci Rep
September 2024
Department of Physics, Institute for Advanced Studies in Basic Sciences, Zanjan, 45195-1159, Iran.
In this work, the propagation of OAM modes in multimode interference (MMI) waveguides, as the basic elements in many integrated optical devices, is studied to utilize their benefits in integrated OAM applications. OAM modes shape the OAM-maintaining image at the specific length of an MMI waveguide. As the most effective parameters on the properties of the generated image, waveguide's width (W), topological charge ( ) and waist radius (WR) of the input OAM modes are investigated.
View Article and Find Full Text PDFIn this paper, we proposed a 2 × 2 multiple-input multiple-output (MIMO) dual spiral octagonal prism liquid dielectric resonator antenna (DRA) with snake-shaped defective ground structure (DGS) for space multiplexing of orbital angular momentum (OAM). The DRA element adopts an inner and outer nested dual spiral structure filled with 0.035 g/ml of brine outside and a cylinder filled with distilled water inside.
View Article and Find Full Text PDFIn this paper, we explore the distribution of the orbital angular momentum (OAM) in the coaxial vortex superposition states based on the independent propagation principle of light in this interference process. We find that in this case, some specific singular points exist in the spatial intensity distribution. The first type of singular point is located at the center point of the spatial intensity distribution.
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