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Proceedings Paper

From q-plates to the photonic gear: tailoring the rotational properties of light
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Paper Abstract

The rotational properties of a light beam are controlled by its spin and orbital angular momentum (SAM and OAM). The q-plate, a liquid crystal device that can give rise to a coupling of these two quantities, was introduced a few years ago, leading to several applications in classical and quantum photonics. Very recently, in particular, a specific kind of q-plate was used to generate rotational-invariant states of single photons, which were then employed for performing a demonstration of quantum key distribution without the need for establishing a common reference frame between the transmitting and the receiving units. This result may find applications in future satellite-based quantum communication. By a similar approach, photonic states having a strongly enhanced rotational sensitivity, as opposed to rotational invariance, can be generated by using q-plates with very high topological charge. Photons in these states can be obtained starting from light having a uniform linear polarization and, after a physical rotation, can be converted back into light having uniformly linear polarization. As a result, one obtains linearly polarized light whose polarization plane rotates by an angle that is proportional to the angle of physical rotation between the generation and detection stages, with a very large proportionality constant. This effect of rotational amplification, which we named “photonic gear”, leads to a sort of “super-resolved Malus’ law”, potentially useful for measuring mechanical angles with very high precision.

Paper Details

Date Published: 25 February 2014
PDF: 10 pages
Proc. SPIE 8999, Complex Light and Optical Forces VIII, 89990H (25 February 2014); doi: 10.1117/12.2036723
Show Author Affiliations
Lorenzo Marrucci, Univ. degli Studi di Napoli Federico II (Italy)
CNR-SPIN, Complesso Univ. di Monte S. Angelo (Italy)
Fabio Sciarrino, Univ. degli Studi di Roma La Sapienza (Italy)

Published in SPIE Proceedings Vol. 8999:
Complex Light and Optical Forces VIII
David L. Andrews; Enrique J. Galvez; Jesper Glückstad, Editor(s)

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