Orbital Angular Momentum of photons

88 Pages·2016·10.38 MB·English

by  Andre C. Marta

Orbital Angular Momentum of photons:
a tool to transmit information
João David Ventura Sabino
Thesis to obtain the Master of Science Degree in
Engineering Physics
Supervisor(s): Professor Gonçalo Nuno Marmelo Foito Figueira
Professor Paulo Sérgio de Brito André
Examination Committee
Chairperson: Professor Horácio João Matos Fernandes
Supervisor: Professor Paulo Sérgio de Brito André
Member of the Committee: Professor Jorge Miguel Ramos Domingues Ferreira Vieira
Professor José Maria Longras Figueiredo
November 2016
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AoAmordaquelesquenuncadeixamdeacreditar.
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Acknowledgments
I’d like to start by thanking my family. The support form L´ıdia, Joa˜o and Filipe was crucial to make this
journeypossible. I’dalsoliketothankmygirlfriendPatr´ıciawhoalsoofferedunconditionalsupport,not
only with suggestions to this work but also in the reviewing of this document. The five people above
gavemethemostimportantthingsIneeded: Talks,jokes,andsmiles.
Professor Gonc¸alo Figueira from the Group of Lasers and Plasmas (GoLP) and professor Paulo
Andre´ fromInstitutodeTelecomunicac¸o˜es(IT)alsomadethisworkpossiblethroughallthesupportand
encouragementprovided.
ImustthankGoLPandInstitutodePlasmaseFusa˜oNuclear(IPFN)forprovidingtheLaborato´riode
LasersIntensos(L2I),theinstallationwheretheexperimentwasperformed,andmanyopticalmaterials
that were necessary. I also thank IT for the provided equipment without which the experiment couldn’t
beperformed.
AwordmustbelefttoalltheniceGoLPteam,namelyCelsoJoa˜o,HugoPires,VictorHariton,Joana
Duarte,whowerealwaysavailabletohelpedmetoovercomesomeobstacles.
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Resumo
Os sistemas de comunicac¸o˜es sofreram uma grande evoluc¸a˜o na segunda metade do se´culo XXI,
permitindo melhores e mais ra´pidas comunicac¸o˜es em qualquer parte do mundo. Em particular, as
comunicac¸o˜es o´pticas tornaram-se o pilar central das comunicac¸o˜es por cabo de alta capacidade. O
volumedetra´ficodedadosnainternetesta´ aatingirrapidamenteoslimitesimpostospelosefeitosna˜o
lineares da fibra o´ptica. O Momento Angular Orbital (OAM) da luz e´ uma potencial soluc¸a˜o, uma vez
que permite a gerac¸a˜o de modos ortogonais, adicionando assim um grau de liberdade extra para o
transportedeinformac¸a˜o. Nestetrabalhoforamdesenvolvidassimulac¸o˜esparamodelarapropagac¸a˜o
edifracc¸a˜odefeixescomMAOefoitambe´mexecutadaumatransmissa˜odeinformac¸a˜ousandoMAO,
provandoqueestapropriedadedaluzpodeserusadaparaaumentaraeficieˆnciaespectraldasactuais
redesdecomunicac¸o˜es.
Palavras-chave:
Momento Angular Orbital, Comunicac¸o˜es o´pticas, Eficieˆncia espectral,
ModuladorEspacialdaLuz,Modulac¸a˜odefase
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Abstract
Communication systems have seen a great evolution in the second half of last century, allowing faster
and better communications all over the world. In particular, optical communications have become the
backboneofhighcapacitywiredcommunucations. Theinternetdatatrafficcapacityisrapidlyreaching
the limits imposed by optical fiber non-linear effects. Orbital Angular Momentum (OAM) of light is a
potentialsolutionthatpermitsthegenerationofunlimitedorthogonalmodeswhichaddsanotherdegree
of freedom to carry information. In this work simulations are developed as a model to the propagation
and diffraction of OAM-carrying beams and a proof-of-concept information transmission using OAM is
also implemented, showing that this property of light can be used to increase the spectral efficiency of
today’snetworks.
Keywords:
Orbital Angular Momentum, Optical communications, Spectral efficiency, Spatial
LightModulator,Phasemodulation
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