scholarly journals Nonlinear Metasurface for Structured Light with Tunable Orbital Angular Momentum

2019 ◽  
Vol 9 (5) ◽  
pp. 958 ◽  
Author(s):  
Yun Xu ◽  
Jingbo Sun ◽  
Jesse Frantz ◽  
Mikhail Shalaev ◽  
Wiktor Walasik ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Communication Systems ◽  
Near Infrared ◽  
Transmission Efficiency ◽  
Photon Absorption ◽  
New Paradigm ◽  
Infrared Wavelength ◽  
Infrared Spectral ◽  
Two Photon Absorption Coefficient

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.

scholarly journals Giant optical anisotropy in transition metal dichalcogenides for next-generation photonics

2020 ◽  
Author(s):  
Georgy Ermolaev ◽  
D. Grudinin ◽  
Y. Stebunov ◽  
K. Voronin ◽  
Vasyl Kravets ◽  
...  
Keyword(s):  
Transition Metal ◽  
Optical Anisotropy ◽  
Near Infrared ◽  
Near Field ◽  
Transition Metal Dichalcogenides ◽  
Next Generation ◽  
Infrared Wavelength ◽  
Infrared Spectral ◽  
Metal Dichalcogenides ◽  
On Chip

Abstract Large optical anisotropy observed in a broad spectral range is of paramount importance for efficient light manipulation in countless devices. Although a giant anisotropy was recently observed in the mid-infrared wavelength range, for visible and near-infrared spectral intervals, the problem remains acute with the highest reported birefringence values of 0.8 in BaTiS3 and h-BN crystals. This inspired an intensive search for giant optical anisotropy among natural and artificial materials. Here, we demonstrate that layered transition metal dichalcogenides (TMDCs) provide an answer to this quest owing to their fundamental differences between intralayer strong covalent bonding and weak interlayer van der Walls interaction. To do this, we carried out a correlative far- and near-field characterization validated by first-principle calculations that reveals an unprecedented birefringence of 1.5 in the infrared and 3 in the visible light for MoS2. Our findings demonstrate that this outstanding anisotropy allows for tackling the diffraction limit enabling an avenue for on-chip next-generation photonics.

scholarly journals Metasurface Spiral Focusing Generators with Tunable Orbital Angular Momentum Based on Slab Silicon Nitride Waveguide and Vanadium Dioxide (VO2)

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1864
Author(s):  
Li Chen ◽  
Lin Zhao ◽  
Yuan Hao ◽  
Wenyi Liu ◽  
Yi Wu ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Vanadium Dioxide ◽  
Communication Systems ◽  
High Speed ◽  
Focal Length ◽  
Polarized Light ◽  
Optical Systems ◽  
Gaussian Beams ◽  
The Impact

The metasurface spiral focusing (MSF) generator has gained attention in high-speed optical communications due to its spatial orthogonality. However, previous MSF generators only can generate a single orbital angular momentum (OAM) mode for one polarized light. Here, a MSF generator with tunable OAM is proposed and it has the ability to transform linearly polarized light (LPL), circularly polarized light or Gaussian beams into vortex beams which can carry tunable OAM at near-infrared wavelength by controlling the phase transition of vanadium dioxide (VO2). Utilizing this MSF generator, the beams can be focused on several wavelength-sized rings with efficiency as high as 76%, 32% when VO2 are in the insulating phase and in the metallic phase, respectively. Moreover, we reveal the relationship between the reflective focal length and transmissive focal length, and the latter is 2.3 times of the former. We further demonstrate the impact of Gaussian beams with different waist sizes on MSF generators: the increase in waist size produces the enhancement in spiral focusing efficiency and the decrease in size of focal ring. The MSF generator we proposed will be applicable to a variety of integrated compact optical systems, such as optical communication systems and optical trapping systems.

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

2018 ◽  
Vol 8 (11) ◽  
pp. 2179 ◽  
Author(s):  
Zhen Qu ◽  
Ivan Djordjevic
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Optical Communication ◽  
Free Space ◽  
Communication Systems ◽  
Huffman Coding ◽  
Free Space Optical Communication ◽  
Free Space Optical ◽  
Optical Communication Systems ◽  
Space Optical Communication

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.

scholarly journals Near-infrared dyes for two-photon absorption in the short-wavelength infrared: strategies towards optical power limiting

2021 ◽  
Author(s):  
Simon Pascal ◽  
Sylvain David ◽  
Chantal Andraud ◽  
Olivier Maury
Keyword(s):  
Spectral Range ◽  
Short Wavelength ◽  
Near Infrared ◽  
Optical Power ◽  
Photon Absorption ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Infrared Spectral Range ◽  
Infrared Spectral ◽  
Optical Power Limiting

The recent advances in the field of two-photon absorbing chromophores in the short-wavelength infrared spectral range (SWIR 1100–2500 nm) are summarized, highlighting the development of optical power limiting devices in this spectral range.

scholarly journals Received Probability of Orbital-Angular-Momentum Modes Carried by Diffraction- and Attenuation- Resistant Beams in Weak Turbulent Oceans

2020 ◽  
Vol 8 (9) ◽  
pp. 701
Author(s):  
Yuan Zheng ◽  
Dongyu Yang ◽  
Shiqing Qin ◽  
Yixin Zhang
Keyword(s):  
Refractive Index ◽  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Optical Communication ◽  
Communication System ◽  
Dissipation Rate ◽  
Communication Systems ◽  
Probability Model ◽  
Complex Refractive Index ◽  
Optical Communication Systems

High performance underwater wireless optical communication systems are the key to the construction of high quality underwater optical communication networks. However, seawater absorption and seawater turbulent diffraction should be the main factors limiting the performance of underwater optical communication systems. For this reason, we established the probability model of the orbital angular momentum (OAM) mode received by the communication system to study the influence of the absorbable turbulent seawater channel on the underwater optical communication system with an anti-diffraction and anti-attenuation random (DARR) beam as the signal carrier. In the study, the DARR beam with a large truncated Gaussian aperture was adopted as the signal carrier, seawater absorption was characterized by the complex refractive index of seawater, and seawater turbulence was described by the power spectrum of the refractive index of seawater. By analyzing the relationship between the received probability of the OAM mode of DARR beams and the dissipation rate of kinetic energy per unit of mass of fluid, the ratio of temperature and salinity, dissipation rate of the mean-squared temperature, and other parameters, we show that one can select longer wavelength, smaller OAM quantum number and smaller received diameter to increase the received probability of OAM signal modes. The disturbance of turbulent seawater to the OAM modes with different quantum numbers carried by the DARR beam is less than the corresponding OAM modes carried by the Laguerre–Gaussian beam. Our paper shows that the DARR beam can mitigate the absorption and disturbance of turbulent seawater.

scholarly journals Giant optical anisotropy in transition metal dichalcogenides for next-generation photonics

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
G. A. Ermolaev ◽  
D. V. Grudinin ◽  
Y. V. Stebunov ◽  
K. V. Voronin ◽  
V. G. Kravets ◽  
...  
Keyword(s):  
Transition Metal ◽  
Optical Anisotropy ◽  
Near Infrared ◽  
Near Field ◽  
Transition Metal Dichalcogenides ◽  
Next Generation ◽  
Infrared Wavelength ◽  
Infrared Spectral ◽  
Metal Dichalcogenides ◽  
On Chip

AbstractLarge optical anisotropy observed in a broad spectral range is of paramount importance for efficient light manipulation in countless devices. Although a giant anisotropy has been recently observed in the mid-infrared wavelength range, for visible and near-infrared spectral intervals, the problem remains acute with the highest reported birefringence values of 0.8 in BaTiS3 and h-BN crystals. This issue inspired an intensive search for giant optical anisotropy among natural and artificial materials. Here, we demonstrate that layered transition metal dichalcogenides (TMDCs) provide an answer to this quest owing to their fundamental differences between intralayer strong covalent bonding and weak interlayer van der Waals interaction. To do this, we made correlative far- and near-field characterizations validated by first-principle calculations that reveal a huge birefringence of 1.5 in the infrared and 3 in the visible light for MoS2. Our findings demonstrate that this remarkable anisotropy allows for tackling the diffraction limit enabling an avenue for on-chip next-generation photonics.

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