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Experimental evaluation of complex optical adaptive arrays in free-space coherent laser communications

Total activity: 1
Type of activity
Competitive project
Funding entity
Funding entity code
139.792,80 €
Start date
End date
Optical free-space communication will be a key building block for future information systems in free-space
environments. Wireless optical communications can be used for ground-to-ground links, satellite-to-satellite
crosslinks, and up-and-down links between space platforms and aircraft, ships, and other ground platforms. Also,
recent successes of laboratory and space demonstrations of free-space optical communications indicate that
coherent technology is near to be ready for operational deployment. However, when the link includes part of the
atmosphere, clear-air turbulence induces serious phase distortions and fading to the coherent link. The phase
distortions can be larger than 2p, and the fading can be tens of decibels and, consequently, the channel must be
treated as random for the design of the optical-communication system and the corresponding network.
Detection of coherent optical communication through atmospheric turbulence is difficult because the atmosphere
destroys the phase, which is the carrier of the information. In a coherent receiver the phase compromised beam
is superimposed by a perfect local oscillator beam, which results in a very poor overall modulation contrast.
Fortunately, techniques can be used to reduce significantly the effects of turbulence in the performance of the
coherent communication links. First, the use of coherent signal processing can reduce atmospheric interference
significantly. Then, it is possible to use spatial diversity and simple signal combining techniques to mitigate
turbulence-induced signal fluctuations on coherent systems. We aim in this project at addressing analytically this
research problem as it has become instrumental for the development of feasible free-space laser
The ultimate goal is to replace in laser communications the single receiver with a receiver array, where each
individual detector observes a different section of the received beam. Due to atmospheric turbulence the
individual detectors of the array will detect different amplitudes and phases, which shall be phase corrected and
combined in the optoelectrical domain. Thus, the activity will investigate the feasibility to electro-optically restore
the modulation contents of an atmospherically distorted optical signal.
We list four objectives that need to be pursued in this project.
1) Determine the feasibility of coherent adaptive array technologies for reliable free-space laser
2) Specify the value added by the array receiver technology on coherent, laser communications for high data
rate links.
3) Provide a detailed theoretical and experimental investigation into the viability of such solution in view of
present and future services development supported by optical communication systems.
4) Identify by experimentation the research developments necessary in the future and the next steps required in technical terms to effectively establish coherent adaptive array technologies as a reliable solution.
The purpose of the project is to assess the feasibility of using these array techniques (as described below in the
proposal) to improve the reliability of high data-rate optical communications developments. Also, key in this
project is to advance coherent optical communications in terms of its use of phase information for providing
scalable channel capacity, increasing link availability, and providing for complex modulation formats.
Array combining, Comunicaciones ópticas, Comunicaciones ópticas inalámbricas, Propagación atmosférica, Sistemas coherentes
Adm. Estat
Plan Nacional de Investigación Científica, Desarrollo e Innovación Tecnológica 2008-2011
Resoluton year
Funcding program
Tecnología Electrónica y de Comunicaciones
Funding subprogram
Tecnologías de comunicaciones
Funding call
Proyectos de investigación y acciones complementarias-TECSUB
Grant institution
Gobierno De España. Ministerio De Economía Y Competitividad, Mineco


Scientific and technological production

1 to 1 of 1 results
  • Multi-wavelength aerosol LIDAR signal pre-processing: practical considerations  Open access

     Rodriguez-Gomez, A.; Rocadenbosch, F.; Sicard, M.; Lange, D.; Barragan, R.; Batet, O.; Comeron, A.; López-Márquez, M.A.; Muñoz, C.; Tiana-Alsina, J.; Tomás, S.
    IOP conference series: earth and environment
    Vol. 28, num. 012013, p. 1-7
    DOI: 10.1088/1755-1315/28/1/012013
    Date of publication: 2015-12
    Journal article
    Access to the full text