Engineering Entangled Photons for Transmission in Ring-Core Optical Fibers

The capacity of optical communication channels can be increased by space division multiplexing in structured optical fibers. Radial core optical fibers allows for the propagation of twisted light–eigenmodes of orbital angular momentum, which have attracted considerable attention for high-dimensional quantum information. Here we study the generation of entangled photons that are tailor-made for coupling into ring core optical fibers. We show that the coupling of photon pairs produced by parametric down-conversion can be increased by close to a factor of three by pumping the non-linear crystal with a perfect vortex mode with orbital angular momentum ℓ, rather than a gaussian mode. Moreover, the two-photon orbital angular momentum spectrum has a nearly constant shape. This provides an interesting scenario for quantum state engineering, as pumping the crystal with a superposition of perfect vortex modes can be used in conjunction with the mode filtering properties of the ring core fiber to produce simple and interesting quantum states.

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Analysis of Bending-Induced Degradation of Orbital Angular Momentum Modes in Optical Fibers

Photonics ◽

10.3390/photonics6030097 ◽

2019 ◽

Vol 6 (3) ◽

pp. 97 ◽

Cited By ~ 1

Author(s):

Lee ◽

Song ◽

Kim

Keyword(s):

Angular Momentum ◽

Quantitative Analysis ◽

Optical Fibers ◽

Orbital Angular Momentum ◽

Topological Charge ◽

Charge Number ◽

Crystal Fiber ◽

Core Fiber ◽

Bending Losses ◽

Ring Core

In this work, bending-induced deterioration of orbital angular momentum (OAM) modes in ring core fiber (RCF), photonic crystal fiber (PCF), and vortex fiber (VF) was theoretically investigated: Bending losses, coupling losses, and intermodal crosstalk at the interface between straight and bent optical fibers were investigated from the modal analysis of those three types of OAM mode fibers. In addition, the degradation of a topological charge number of an OAM mode due to the bending-induced birefringence and horizontal mode asymmetry was also investigated. Our investigation revealed that, in all aspects, the PCF is most robust to bending among the three types of optical fibers, and the most serious bending-induced problem in the VF and the RCF is the degradation of the topological charge number. The allowed minimum bending radii of VF and RCF appeared to be ~15 and ~45 mm, respectively, for the specific structures considered in this work. We expect that the methodology and results of our quantitative analysis on bending-induced degradation of OAM modes will be of great use in the design of OAM mode fibers for practical use.

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Generation, Transmission and Application of Orbital Angular Momentum in Optical Fiber: A Review

Frontiers in Physics ◽

10.3389/fphy.2021.773505 ◽

2021 ◽

Vol 9 ◽

Author(s):

Minghao Ma ◽

Yudong Lian ◽

Yulei Wang ◽

Zhiwei Lu

Keyword(s):

Angular Momentum ◽

Optical Fibers ◽

Orbital Angular Momentum ◽

Optical Systems ◽

Necessary Condition ◽

Fiber Grating ◽

Crystal Fiber ◽

Effective Use ◽

Propagation Properties ◽

Ring Core

Optical orbital angular momentum (OAM) has become a hot research topic because of its unique properties due to its spiral distribution of phases. The production and transmission of OAM has also become a necessary condition for effective use of OAM. As an optical waveguide with good propagation properties, optical fibers are used in optical systems supporting OAM. This paper introduces the OAM generation and transmission system based on fiber, summarizes the current photonic crystal fiber, ring core fiber, fiber grating and other all-fiber systems that can support OAM modes, and explains some experimental principles. Finally, an outlook on OAM generation or transmission devices for all-fiber systems is presented, providing a useful reference for future related research.

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Highly dispersive coupled ring-core fiber for orbital angular momentum modes

Applied Physics Letters ◽

10.1063/5.0025615 ◽

2020 ◽

Vol 117 (19) ◽

pp. 191101

Author(s):

Wenpu Geng ◽

Yiqiao Li ◽

Yuxi Fang ◽

Yingning Wang ◽

Changjing Bao ◽

...

Keyword(s):

Angular Momentum ◽

Orbital Angular Momentum ◽

Core Fiber ◽

Ring Core

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Ring-Core Photonic Crystal Fiber of Terahertz Orbital Angular Momentum Modes with Excellence Guiding Properties in Optical Fiber Communication

Photonics ◽

10.3390/photonics8040122 ◽

2021 ◽

Vol 8 (4) ◽

pp. 122

Author(s):

Fahad Ahmed Al-Zahrani ◽

Md. Anowar Kabir

Keyword(s):

Angular Momentum ◽

Photonic Crystal ◽

Photonic Crystal Fiber ◽

Orbital Angular Momentum ◽

High Capacity ◽

Optical Fiber Communication ◽

Fused Silica ◽

Confinement Loss ◽

Crystal Fiber ◽

Ring Core

The orbital angular momentum (OAM) of light is used for increasing the optical communication capacity in the mode division multiplexing (MDM) technique. A novel and simple structure of ring-core photonic crystal fiber (RC-PCF) is proposed in this paper. The ring core is doped by the Schott sulfur difluoride material and the cladding region is composed of fused silica with one layer of well-patterned air-holes. The guiding of Terahertz (THz) OAM beams with 58 OAM modes over 0.70 THz (0.20 THz–0.90 THz) frequency is supported by this proposed RC-PCF. The OAM modes are well-separated for their large refractive index difference above 10−4. The dispersion profile of each mode is varied in the range of 0.23–7.77 ps/THz/cm. The ultra-low confinement loss around 10−9 dB/cm and better mode purity up to 0.932 is achieved by this RC-PCF. For these good properties, the proposed fiber is a promising candidate to be applied in the THz OAM transmission systems with high feasibility and high capacity.

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