scholarly journals The angular momentum of twisted light in anisotropic media: chiroptical interactions in chiral and achiral materials

2018 ◽  
Author(s):  
David L. Andrews ◽  
Kayn A. Forbes
Keyword(s):  
Angular Momentum ◽  
Anisotropic Media ◽  
Twisted Light

Quantized optical orbital angular momentum precession and nutation in a twisted light

2020 ◽  
Vol 95 (8) ◽  
pp. 085509
Author(s):  
Zhuoyuan Wang ◽  
Shi Yao Chong ◽  
Peihong Cheng ◽  
Peng An ◽  
Jian Qi Shen
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Twisted Light

scholarly journals Origins and demonstrations of electrons with orbital angular momentum

2017 ◽  
Vol 375 (2087) ◽  
pp. 20150434 ◽  
Author(s):  
Benjamin J. McMorran ◽  
Amit Agrawal ◽  
Peter A. Ercius ◽  
Vincenzo Grillo ◽  
Andrew A. Herzing ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Free Space ◽  
Rest Mass ◽  
Wave Functions ◽  
Matter Wave ◽  
Optical Manipulation ◽  
Electron Wave ◽  
Mechanical Wave ◽  
Twisted Light

The surprising message of Allen et al. (Allen et al. 1992 Phys. Rev. A 45 , 8185 ( doi:10.1103/PhysRevA.45.8185 )) was that photons could possess orbital angular momentum in free space, which subsequently launched advancements in optical manipulation, microscopy, quantum optics, communications, many more fields. It has recently been shown that this result also applies to quantum mechanical wave functions describing massive particles (matter waves). This article discusses how electron wave functions can be imprinted with quantized phase vortices in analogous ways to twisted light, demonstrating that charged particles with non-zero rest mass can possess orbital angular momentum in free space. With Allen et al. as a bridge, connections are made between this recent work in electron vortex wave functions and much earlier works, extending a 175 year old tradition in matter wave vortices. This article is part of the themed issue ‘Optical orbital angular momentum’.

scholarly journals Controlling light’s helicity at the source: orbital angular momentum states from lasers

2017 ◽  
Vol 375 (2087) ◽  
pp. 20150436 ◽  
Author(s):  
Andrew Forbes
Keyword(s):  
Angular Momentum ◽  
Solid State ◽  
Orbital Angular Momentum ◽  
Laser Cavity ◽  
Solid State Lasers ◽  
On Demand ◽  
Twisted Light ◽  
Optical Modes ◽  
On Chip

Optical modes that carry orbital angular momentum (OAM) are routinely produced external to the laser cavity and have found a variety of applications, thus increasing the demand for integrated solutions for their production. Yet such modes are notoriously difficult to produce from lasers due to the strict symmetry requirements for their creation, together with the need to break the degeneracy in helicity. Here, we review the progress made since 1992 in producing such twisted light modes directly at the source, from gas to solid-state lasers, bulk to integrated on-chip solutions, through to generic devices for on-demand OAM in both scalar and vector forms. This article is part of the themed issue ‘Optical orbital angular momentum’.

scholarly journals Twisted light transmission over 143 km

2016 ◽  
Vol 113 (48) ◽  
pp. 13648-13653 ◽  
Author(s):  
Mario Krenn ◽  
Johannes Handsteiner ◽  
Matthias Fink ◽  
Robert Fickler ◽  
Rupert Ursin ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Adaptive Optics ◽  
Orbital Angular Momentum ◽  
Free Space ◽  
Light Transmission ◽  
Short Message ◽  
Spatial Modes ◽  
Twisted Light ◽  
Transmission Quality

Spatial modes of light can potentially carry a vast amount of information, making them promising candidates for both classical and quantum communication. However, the distribution of such modes over large distances remains difficult. Intermodal coupling complicates their use with common fibers, whereas free-space transmission is thought to be strongly influenced by atmospheric turbulence. Here, we show the transmission of orbital angular momentum modes of light over a distance of 143 km between two Canary Islands, which is 50× greater than the maximum distance achieved previously. As a demonstration of the transmission quality, we use superpositions of these modes to encode a short message. At the receiver, an artificial neural network is used for distinguishing between the different twisted light superpositions. The algorithm is able to identify different mode superpositions with an accuracy of more than 80% up to the third mode order and decode the transmitted message with an error rate of 8.33%. Using our data, we estimate that the distribution of orbital angular momentum entanglement over more than 100 km of free space is feasible. Moreover, the quality of our free-space link can be further improved by the use of state-of-the-art adaptive optics systems.

scholarly journals Measurement of the spin of the M87 black hole from its observed twisted light

2019 ◽  
Vol 492 (1) ◽  
pp. L22-L27 ◽  
Author(s):  
Fabrizio Tamburini ◽  
Bo Thidé ◽  
Massimo Della Valle
Keyword(s):  
Black Hole ◽  
Angular Momentum ◽  
Observational Evidence ◽  
Rotation Parameter ◽  
Intensity Data ◽  
Wavefront Reconstruction ◽  
Recovery Techniques ◽  
Physical Observable ◽  
Twisted Light ◽  
Radio Intensity

ABSTRACT We present the first observational evidence that light propagating near a rotating black hole is twisted in phase and carries orbital angular momentum (OAM). This physical observable allows a direct measurement of the rotation of the black hole. We extracted the OAM spectra from the radio intensity data collected by the Event Horizon Telescope from around the black hole M87* by using wavefront reconstruction and phase recovery techniques and from the visibility amplitude and phase maps. This method is robust and complementary to black hole shadow circularity analyses. It shows that the M87* rotates clockwise with an estimated rotation parameter a = 0.90 ± 0.05 with an $\sim 95{{\ \rm per\ cent}}$ confidence level (c.l.) and an inclination i = 17° ± 2°, equivalent to a magnetic arrested disc with an inclination i = 163° ± 2°. From our analysis, we conclude that, within a 6σ c.l., the M87* is rotating.

scholarly journals Resolving enantiomers using the optical angular momentum of twisted light

2016 ◽  
Vol 2 (3) ◽  
pp. e1501349 ◽  
Author(s):  
Ward Brullot ◽  
Maarten K. Vanbel ◽  
Tom Swusten ◽  
Thierry Verbiest
Keyword(s):  
Angular Momentum ◽  
Circular Dichroism ◽  
Molecular System ◽  
Optical Rotation ◽  
Electric Quadrupole ◽  
Pharmaceutical Drugs ◽  
Chiral Molecules ◽  
Twisted Light ◽  
Nanoparticle Aggregates ◽  
Circular Dichroïsm

Circular dichroism and optical rotation are crucial for the characterization of chiral molecules and are of importance to the study of pharmaceutical drugs, proteins, DNA, and many others. These techniques are based on the different interactions of enantiomers with circularly polarized components of plane wave light that carries spin angular momentum (SAM). For light carrying orbital angular momentum (OAM), for example, twisted or helical light, the consensus is that it cannot engage with the chirality of a molecular system as previous studies failed to demonstrate an interaction between optical OAM and chiral molecules. Using unique nanoparticle aggregates, we prove that optical OAM can engage with materials’ chirality and discriminate between enantiomers. Further, theoretical results show that compared to circular dichroism, mainly based on magnetic dipole contributions, the OAM analog helical dichroism (HD) is critically dependent on fundamentally different chiral electric quadrupole contributions. Our work opens new venues to study chirality and can find application in sensing and chiral spectroscopy.

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