Editorial

4 pages, 170 KiB

Open AccessEditorial

Special Issue on Novel Insights into Orbital Angular Momentum Beams: From Fundamentals, Devices to Applications

by Yang Yue, Hao Huang, Yongxiong Ren, Zhongqi Pan and Alan E. Willner

Appl. Sci. 2019, 9(13), 2600; https://doi.org/10.3390/app9132600 - 27 Jun 2019

Cited by 3 | Viewed by 2126

It is well-known now that angular momentum carried by elementary particles can be categorized as spin angular momentum (SAM) and orbital angular momentum (OAM) [...] Full article

(This article belongs to the Special Issue Novel Insights into Orbital Angular Momentum Beams: From Fundamentals, Devices to Applications)

Research

Jump to: Editorial, Review

15 pages, 4532 KiB

Open AccessFeature PaperArticle

Holographic Silicon Metasurfaces for Total Angular Momentum Demultiplexing Applications in Telecom

by Gianluca Ruffato, Michele Massari, Pietro Capaldo and Filippo Romanato

Appl. Sci. 2019, 9(11), 2387; https://doi.org/10.3390/app9112387 - 11 Jun 2019

Cited by 2 | Viewed by 3792

Abstract

The simultaneous processing of orbital angular momentum (OAM) and polarization has recently acquired particular importance and interest in a wide range of fields ranging from telecommunications to high-dimensional quantum cryptography. Due to their inherently polarization-sensitive optical behavior, Pancharatnam–Berry optical elements (PBOEs), acting on [...] Read more.

The simultaneous processing of orbital angular momentum (OAM) and polarization has recently acquired particular importance and interest in a wide range of fields ranging from telecommunications to high-dimensional quantum cryptography. Due to their inherently polarization-sensitive optical behavior, Pancharatnam–Berry optical elements (PBOEs), acting on the geometric phase, have proven to be useful for the manipulation of complex light beams with orthogonal polarization states using a single optical element. In this work, different PBOEs have been computed, realized, and optically analyzed for the sorting of beams with orthogonal OAM and polarization states at the telecom wavelength of 1310 nm. The geometric-phase control is obtained by inducing a spatially-dependent form birefringence on a silicon substrate, patterned with properly-oriented subwavelength gratings. The digital grating structure is generated with high-resolution electron beam lithography on a resist mask and transferred to the silicon substrate using inductively coupled plasma-reactive ion etching. The optical characterization of the fabricated samples confirms the expected capability to detect circularly-polarized optical vortices with different handedness and orbital angular momentum. Full article

(This article belongs to the Special Issue Novel Insights into Orbital Angular Momentum Beams: From Fundamentals, Devices to Applications)

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8 pages, 2630 KiB

Open AccessArticle

Mode-Selective Photonic Lanterns for Orbital Angular Momentum Mode Division Multiplexing

by Yan Li, Yang Li, Lipeng Feng, Chen Yang, Wei Li, Jifang Qiu, Xiaobin Hong, Yong Zuo, Hongxiang Guo, Weijun Tong and Jian Wu

Appl. Sci. 2019, 9(11), 2233; https://doi.org/10.3390/app9112233 - 30 May 2019

Cited by 10 | Viewed by 2765

Abstract

We analyze the mode evolution in mode-selective photonic lanterns with respect to taper lengths, affected by possible mode phase differences varying along the taper. As a result, we design a three-mode orbital angular momentum (OAM) mode-selective photonic lantern by optimizing the taper length [...] Read more.

We analyze the mode evolution in mode-selective photonic lanterns with respect to taper lengths, affected by possible mode phase differences varying along the taper. As a result, we design a three-mode orbital angular momentum (OAM) mode-selective photonic lantern by optimizing the taper length with mode crosstalk below −24 dB, which employs only one single mode fiber port to selectively generate one OAM mode. Full article

(This article belongs to the Special Issue Novel Insights into Orbital Angular Momentum Beams: From Fundamentals, Devices to Applications)

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13 pages, 5404 KiB

Open AccessArticle

An Evaluation of Orbital Angular Momentum Multiplexing Technology

by Doohwan Lee, Hirofumi Sasaki, Hiroyuki Fukumoto, Yasunori Yagi and Takashi Shimizu

Appl. Sci. 2019, 9(9), 1729; https://doi.org/10.3390/app9091729 - 26 Apr 2019

Cited by 30 | Viewed by 4389

Abstract

This paper reports our investigation of wireless communication performance obtained using orbital angular momentum (OAM) multiplexing, from theoretical evaluation to experimental study. First, we show how we performed a basic theoretical study on wireless OAM multiplexing performance regarding modulation, demodulation, multiplexing, and demultiplexing. [...] Read more.

This paper reports our investigation of wireless communication performance obtained using orbital angular momentum (OAM) multiplexing, from theoretical evaluation to experimental study. First, we show how we performed a basic theoretical study on wireless OAM multiplexing performance regarding modulation, demodulation, multiplexing, and demultiplexing. This provided a clear picture of the effects of mode attenuation and gave us insight into the potential and limitations of OAM wireless communications. Then, we expanded our study to experimental evaluation of a dielectric lens and end-to-end wireless transmission on 28 gigahertz frequency bands. To overcome the beam divergence of OAM multiplexing, we propose a combination of multi-input multi-output (MIMO) and OAM technology, named OAM-MIMO multiplexing. We achieved 45 Gbps (gigabits per second) throughput using OAM multiplexing with five OAM modes. We also experimentally demonstrated the effectiveness of the proposed OAM-MIMO multiplexing using a total of 11 OAM modes. Experimental OAM-MIMO multiplexing results reached a new milestone for point-to-point transmission rates when 100 Gbps was achieved at a 10-m transmission distance. Full article

(This article belongs to the Special Issue Novel Insights into Orbital Angular Momentum Beams: From Fundamentals, Devices to Applications)

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31 pages, 6861 KiB

Open AccessCommunication

Reception of OAM Radio Waves Using Pseudo-Doppler Interpolation Techniques: A Frequency-Domain Approach

by Marek Klemes

Appl. Sci. 2019, 9(6), 1082; https://doi.org/10.3390/app9061082 - 14 Mar 2019

Cited by 7 | Viewed by 4381

Abstract

This paper presents a practical method of receiving waves having orbital angular momentum (OAM) in the far field of an antenna transmitting multiple OAM modes, each carrying a separate data stream at the same radio frequency (RF). The OAM modes are made to [...] Read more.

This paper presents a practical method of receiving waves having orbital angular momentum (OAM) in the far field of an antenna transmitting multiple OAM modes, each carrying a separate data stream at the same radio frequency (RF). The OAM modes are made to overlap by design of the transmitting antenna structure. They are simultaneously received at a known far-field distance using a minimum of two antennas separated by a short distance tangential to the OAM conical beams’ maxima and endowed with different pseudo-Doppler frequency shifts by a modulating arrangement that dynamically interpolates their phases between the two receiving antennas. Subsequently down-converted harmonics of the pseudo-Doppler shifted spectra are linearly combined by sets of weighting coefficients which effectively separate each OAM mode in the frequency domain, resulting in a higher signal-to-noise ratios (SNR) than possible using spatial-domain OAM reception techniques. Moreover, no more than two receiving antennas are necessary to separate any number of OAM modes in principle, unlike conventional MIMO (Multi-Input, Multi-Output) which requires at least K antennas to resolve K spatial modes. Full article

(This article belongs to the Special Issue Novel Insights into Orbital Angular Momentum Beams: From Fundamentals, Devices to Applications)

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11 pages, 10692 KiB

Open AccessArticle

Nonlinear Metasurface for Structured Light with Tunable Orbital Angular Momentum

by Yun Xu, Jingbo Sun, Jesse Frantz, Mikhail I. Shalaev, Wiktor Walasik, Apra Pandey, Jason D. Myers, Robel Y. Bekele, Alexander Tsukernik, Jasbinder S. Sanghera and Natalia M. Litchinitser

Appl. Sci. 2019, 9(5), 958; https://doi.org/10.3390/app9050958 - 06 Mar 2019

Cited by 11 | Viewed by 3768

Abstract

Orbital angular momentum (OAM) beams may create a new paradigm for the future classical and quantum communication systems. A majority of existing OAM beam converters are bulky, slow, and cannot withstand high powers. Here, we design and experimentally demonstrate an ultra-fast, compact chalcogenide-based [...] Read more.

Orbital angular momentum (OAM) beams may create a new paradigm for the future classical and quantum communication systems. A majority of existing OAM beam converters are bulky, slow, and cannot withstand high powers. Here, we design and experimentally demonstrate an ultra-fast, compact chalcogenide-based all-dielectric metasurface beam converter which has the ability to transform a Hermite–Gaussian (HG) beam into a beam carrying an OAM at near infrared wavelength. Depending on the input beam intensity, the topological charge carried by the output OAM beam can be switched between positive and negative. The device provides high transmission efficiency and is fabricated by a standard electron beam lithography. Arsenic trisulfide (As

_{2}

S

_{3}

) chalcogenide glass (ChG) offers ultra-fast and large third-order nonlinearity as well as a low two-photon absorption coefficient in the near infrared spectral range. Full article

(This article belongs to the Special Issue Novel Insights into Orbital Angular Momentum Beams: From Fundamentals, Devices to Applications)

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10 pages, 2751 KiB

Open AccessArticle

Orbital Angular Momentum Multiplexed Free-Space Optical Communication Systems Based on Coded Modulation

by Zhen Qu and Ivan B. Djordjevic

Appl. Sci. 2018, 8(11), 2179; https://doi.org/10.3390/app8112179 - 07 Nov 2018

Cited by 10 | Viewed by 3837

Abstract

In this paper, we experimentally investigate the turbulence mitigation methods in free-space optical communication systems based on orbital angular momentum (OAM) multiplexing. To study the outdoor atmospheric turbulence environment, we use an indoor turbulence emulator. Adaptive optics, channel coding, Huffman coding combined with [...] Read more.

In this paper, we experimentally investigate the turbulence mitigation methods in free-space optical communication systems based on orbital angular momentum (OAM) multiplexing. To study the outdoor atmospheric turbulence environment, we use an indoor turbulence emulator. Adaptive optics, channel coding, Huffman coding combined with low-density parity-check (LDPC) coding, and spatial offset are used for turbulence mitigation; while OAM multiplexing and wavelength-division multiplexing (WDM) are applied to boost channel capacity. Full article

(This article belongs to the Special Issue Novel Insights into Orbital Angular Momentum Beams: From Fundamentals, Devices to Applications)

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Review

Jump to: Editorial, Research

17 pages, 4730 KiB

Open AccessReview

A Review of Tunable Orbital Angular Momentum Modes in Fiber: Principle and Generation

by Lipeng Feng, Yan Li, Sihan Wu, Wei Li, Jifang Qiu, Hongxiang Guo, Xiaobin Hong, Yong Zuo and Jian Wu

Appl. Sci. 2019, 9(12), 2408; https://doi.org/10.3390/app9122408 - 13 Jun 2019

Cited by 14 | Viewed by 3502

Abstract

Orbital angular momentum (OAM) beams, a new fundamental degree of freedom, have excited a great diversity of interest due to a variety of emerging applications. The scalability of OAM has always been a topic of discussion because it plays an important role in [...] Read more.

Orbital angular momentum (OAM) beams, a new fundamental degree of freedom, have excited a great diversity of interest due to a variety of emerging applications. The scalability of OAM has always been a topic of discussion because it plays an important role in many applications, such as expanding to large capacity and adjusting the trapped particle rotation speed. Thus, the generation of arbitrary tunable OAM mode has been paid increasing attention. In this paper, the basic concepts of classical OAM modes are introduced firstly. Then, the tunable OAM modes are categorized into three types according to the orbital angular momentums and polarization states of mode carrying. In order to understand the OAM evolution of a mode intuitively, three kinds of Poincaré spheres (PSs) are introduced to represent the three kinds of tunable OAM modes. Numerous methods generating tunable OAM modes can be roughly divided into two types: spatial and fiber-based generation methods. The principles of fiber-based generation methods are interpreted by introducing two mode bases (linearly-polarized modes and vector modes) of the fiber. Finally, the strengths and weaknesses of each generation method are pointed out and the key challenges for tunable OAM modes are discussed. Full article

(This article belongs to the Special Issue Novel Insights into Orbital Angular Momentum Beams: From Fundamentals, Devices to Applications)

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25 pages, 6110 KiB

Open AccessFeature PaperReview

Generation of Orbital Angular Momentum Modes Using Fiber Systems

by Hongwei Zhang, Baiwei Mao, Ya Han, Zhi Wang, Yang Yue and Yange Liu

Appl. Sci. 2019, 9(5), 1033; https://doi.org/10.3390/app9051033 - 12 Mar 2019

Cited by 41 | Viewed by 7776

Abstract

Orbital angular momentum (OAM) beams, characterized by the helical phase wavefront, have received significant interest in various areas of study. There are many methods to generate OAM beams, which can be roughly divided into two types: spatial methods and fiber methods. As a [...] Read more.

Orbital angular momentum (OAM) beams, characterized by the helical phase wavefront, have received significant interest in various areas of study. There are many methods to generate OAM beams, which can be roughly divided into two types: spatial methods and fiber methods. As a natural shaper of OAM beams, the fibers exhibit unique merits, namely, miniaturization and a low insertion loss. In this paper, we review the recent advances in fiber OAM mode generation systems, in both the interior and exterior of the beams. We introduce the basic concepts of fiber modes and the generation and detection theories of OAM modes. In addition, fiber systems based on different nuclear devices are introduced, including the long-period fiber grating, the mode-selective coupler, microstructural optical fiber, and the photonic lantern. Finally, the key challenges and prospects for fiber OAM mode systems are discussed. Full article

(This article belongs to the Special Issue Novel Insights into Orbital Angular Momentum Beams: From Fundamentals, Devices to Applications)

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17 pages, 535 KiB

Open AccessReview

Optical Helicity and Chirality: Conservation and Sources

by Frances Crimin, Neel Mackinnon, Jörg B. Götte and Stephen M. Barnett

Appl. Sci. 2019, 9(5), 828; https://doi.org/10.3390/app9050828 - 26 Feb 2019

Cited by 38 | Viewed by 6615

Abstract

We consider the helicity and chirality of the free electromagnetic field, and advocate the former as a means of characterising the interaction of chiral light with matter. This is in view of the intuitive quantum form of the helicity density operator, and of [...] Read more.

We consider the helicity and chirality of the free electromagnetic field, and advocate the former as a means of characterising the interaction of chiral light with matter. This is in view of the intuitive quantum form of the helicity density operator, and of the dual symmetry transformation generated by its conservation. We go on to review the form of the helicity density and its associated continuity equation in free space, in the presence of local currents and charges, and upon interaction with bulk media, leading to characterisation of both microscopic and macroscopic sources of helicity. Full article

(This article belongs to the Special Issue Novel Insights into Orbital Angular Momentum Beams: From Fundamentals, Devices to Applications)

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