scholarly journals Multiplication and division of the orbital angular momentum of light with diffractive transformation optics

2019 ◽  
Vol 8 (1) ◽  
Author(s):  
Gianluca Ruffato ◽  
Michele Massari ◽  
Filippo Romanato
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Optical Element ◽  
Input Beam ◽  
Circular Sector ◽  
Optical Elements ◽  
Phase Gradient ◽  
Beam Transmission ◽  
Integer Multiplication ◽  
Optical Transformation

AbstractWe 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.

scholarly journals Pancharatnam–Berry Optical Elements for Spin and Orbital Angular Momentum Division Demultiplexing

Photonics ◽  
2018 ◽  
Vol 5 (4) ◽  
pp. 46 ◽  
Author(s):  
Gianluca Ruffato ◽  
Pietro Capaldo ◽  
Michele Massari ◽  
Alessia Mezzadrelli ◽  
Filippo Romanato
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Silicon Substrate ◽  
Inductively Coupled Plasma ◽  
Optical Element ◽  
Variant Form ◽  
Optical Elements ◽  
Inductively Coupled ◽  
Grating Pattern ◽  
Spatially Variant

A Pancharatnam–Berry optical element is designed, fabricated, and optically characterized for the demultiplexing of beams with different polarization and orbital angular momentum states at the telecom wavelength of 1310 nm. The geometric phase control is achieved by fabricating properly-oriented subwavelength gratings on a silicon substrate, inducing a spatially-variant form birefringence. The digital grating pattern is transferred to the silicon substrate with a two-step nanofabrication protocol, using inductively coupled plasma reactive ion etching to transfer the resist pattern generated with high-resolution electron beam lithography. The optical characterization of the sample confirms the expected capability to sort circularly polarized optical beams with different handedness and orbital angular momentum. Encompassing optical element design and silicon photonics, the designed silicon metasurface paves the way to innovative devices for total angular momentum mode division multiplexing with unprecedented levels of integration.

scholarly journals Holographic Silicon Metasurfaces for Total Angular Momentum Demultiplexing Applications in Telecom

2019 ◽  
Vol 9 (11) ◽  
pp. 2387 ◽  
Author(s):  
Gianluca Ruffato ◽  
Michele Massari ◽  
Pietro Capaldo ◽  
Filippo Romanato
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Silicon Substrate ◽  
Geometric Phase ◽  
Inductively Coupled Plasma ◽  
Optical Element ◽  
Orthogonal Polarization ◽  
Optical Elements ◽  
Wide Range ◽  
Polarization States

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.

scholarly journals A Small-Divergence-Angle Orbital Angular Momentum Metasurface Antenna

Research ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Jianchun Xu ◽  
Ke Bi ◽  
Ru Zhang ◽  
Yanan Hao ◽  
Chuwen Lan ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Electromagnetic Waves ◽  
Divergence Angle ◽  
Compact Structure ◽  
Phase Gradient ◽  
Practical Applications ◽  
Circular Arrangement ◽  
Low Efficiency ◽  
Theoretical Analyses

Electromagnetic waves carrying an orbital angular momentum (OAM) are of great interest. However, most OAM antennas present disadvantages such as a complicated structure, low efficiency, and large divergence angle, which prevents their practical applications. So far, there are few papers and research focuses on the problem of the divergence angle. Herein, a metasurface antenna is proposed to obtain the OAM beams with a small divergence angle. The circular arrangement and phase gradient were used to simplify the structure of the metasurface and obtain the small divergence angle, respectively. The proposed metasurface antenna presents a high transmission coefficient and effectively decreases the divergence angle of the OAM beam. All the theoretical analyses and derivation calculations were validated by both simulations and experiments. This compact structure paves the way to generate OAM beams with a small divergence angle.

Arbitrary spin-to–orbital angular momentum conversion of light

Science ◽  
2017 ◽  
Vol 358 (6365) ◽  
pp. 896-901 ◽  
Author(s):  
Robert C. Devlin ◽  
Antonio Ambrosio ◽  
Noah A. Rubin ◽  
J. P. Balthasar Mueller ◽  
Federico Capasso
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Optical Communication ◽  
Arbitrary Spin ◽  
Spin States ◽  
Spin Angular Momentum ◽  
Optical Elements ◽  
Left And Right ◽  
General Material ◽  
Elliptically Polarized

Optical elements that convert the spin angular momentum (SAM) of light into vortex beams have found applications in classical and quantum optics. These elements—SAM-to–orbital angular momentum (OAM) converters—are based on the geometric phase and only permit the conversion of left- and right-circular polarizations (spin states) into states with opposite OAM. We present a method for converting arbitrary SAM states into total angular momentum states characterized by a superposition of independent OAM. We designed a metasurface that converts left- and right-circular polarizations into states with independent values of OAM and designed another device that performs this operation for elliptically polarized states. These results illustrate a general material-mediated connection between SAM and OAM of light and may find applications in producing complex structured light and in optical communication.

scholarly journals Producing single-photon wave packets of the infrared spectrum range with an orbital angular momentum using “vortex” phase plates

2018 ◽  
Vol 190 ◽  
pp. 04025
Author(s):  
D.A. Turaykhanov ◽  
A.V. Shkalikov ◽  
A.A. Kalachev ◽  
I.R. Imangulova ◽  
N.N. Losevsky ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Single Photon ◽  
Diffractive Optical Elements ◽  
Axially Symmetric ◽  
Optical Elements ◽  
Parametric Down Conversion ◽  
Phase Plates ◽  
Photon States ◽  
Down Conversion

We consider the peculiarities of formation and registration of axially symmetric vortex fields in the context of applying diffractive optical elements such as vortex lenses and vortex axicons for the generation of single-photon states with a nonzero orbital angular momentum in the process of spontaneous parametric down-conversion.

scholarly journals Analog Radio of Fiber Link of 2-Gbaud OOK/BPSK Radio Frequency-Orbital Angular Momentum Beam Transmission over 194-km

2020 ◽  
Author(s):  
Shanguo Huang ◽  
xiyao song ◽  
Xinlu Gao ◽  
Zhennan Zheng ◽  
Zizheng Cao ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Radio Frequency ◽  
Orbital Angular Momentum ◽  
Fiber Link ◽  
Beam Transmission

Efficient measurement of orbital angular momentum using refractive optical elements

2011 ◽  
Author(s):  
Martin P.J. Lavery ◽  
David J. Robertson ◽  
Johannes Courtial ◽  
Gregorius C. G. Berkhout ◽  
Gordon D. Love ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Optical Elements ◽  
Efficient Measurement
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