Skip to main content
SpringerLink
Log in

Free-space laser communications with adaptive optics: Atmospheric compensation experiments

  • Published:
Journal of Optical and Fiber Communications Reports

Abstract

Refractive index inhomogeneities of the turbulent air cause wave-front distortions of optical waves propagating through the atmosphere, leading to such effects as beam spreading, beam wander, and intensity fluctuations (scintillations). These distortions are responsible for severe signal fading in free-space optical communications systems and therefore compromise link reliability. Wave-front distortions can be mitigated, in principle, with adaptive optics, i.e., real-time wave-front control, reducing the likeliness of signal fading. However, adaptive optics technology, currently primarily used in astronomical imaging, needs to be adapted to the requirements of free-space optical communication systems and their specific challenges.

In this chapter we discuss a non-conventional adaptive optics approach that has certain advantages with respect to its incorporation into free-space optical communication terminals. The technique does not require wave-front measurements, which are difficult under the strong scintillation conditions typical for communication scenarios, but is based on the direct optimization of a performance quality metric, e.g., the communication signal strength, with a stochastic parallel gradient descent (SPGD) algorithm.

We describe an experimental adaptive optics system that consists of a beam-steering and a higher-resolution wave-front correction unit with a 132-actuator MEMS piston-type deformable mirror controlled by a VLSI system implementing the SPGD algorithm. The system optimizes the optical signal that could be coupled into a single-mode fiber after propagating along a 2.3-km near-horizontal atmospheric path. We investigate characteristics of the performance metric under different atmospheric conditions and evaluate the effect of the adaptive system. Experiments performed under strong scintillation conditions with beam-steering only as well as with higher-resolution wave-front control demonstrate the mitigation of wave-front distortions and the reduction of signal fading.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Similar content being viewed by others

References

  1. I.S. Reed and X. Chen, Error-Control Coding for Data Networks, Vol. 508 of The Kluwer International Series in Engineering and Computer Science (Kluwer Academic, Boston, 1999).

  2. J.W. Hardy, Adaptive Optics for Astronomical Telescopes, Vol. 16 of Oxford Series in Optical and Imaging Sciences (Oxford University Press, UK, 1998).

  3. F. Roddier, Adaptive Optics in Astronomy (Cambridge University Press, UK, 1999).

  4. C.A. Primmerman T.R. Price R.A. Humphreys B.G. Zollars H.T. Barclay J. Herrmann (1995) ArticleTitleAtmospheric-compensation experiments in strong-scintillation conditions Appl. Opt. 34 2081–2088 Occurrence Handle1995ApOpt..34.2081P Occurrence Handle10.1364/AO.34.002081

    Article  ADS  Google Scholar 

  5. B.M. Levine E.A. Martinsen A. Wirth A. Jankevics M. Toledo-Quinones F. Landers T.L. Bruno (1998) ArticleTitleHorizontal line-of-sight turbulence over near-ground paths and implications for adaptive optics correction in laser communications Appl. Opt. 37 4553–4560 Occurrence Handle1998ApOpt..37.4553L Occurrence Handle10.1364/AO.37.004553

    Article  ADS  Google Scholar 

  6. N.B. Baranova A.V. Mamaev N.F. Pilipetsky V.V. Shkunov B.Y. Zel’dovich (1983) ArticleTitleWave-front dislocations: topological limitations for adaptive systems with phase conjugation J. Opt. Soc. Am 73 525–528 Occurrence Handle1983OSAJ...73..525B

    ADS  Google Scholar 

  7. D.L. Fried (1998) ArticleTitleBranch point problem in adaptive optics J. Opt. Soc. Am. A 15 2759–2768 Occurrence Handle1998OSAJ...15.2759F Occurrence Handle1688265

    ADS  MathSciNet  Google Scholar 

  8. A. Buffington F.S. Crawford R.A. Muller A.J. Schwemin R.G. Smit (1977) ArticleTitleCorrection of atmospheric distortion with an image-sharpening telescope J. Opt. Soc. Am. 67 298–303 Occurrence Handle1977OSAJ...67..298B Occurrence Handle10.1364/JOSA.67.000298

    Article  ADS  Google Scholar 

  9. S.L. McCall T.R. Brown A. Passner (1977) ArticleTitleImproved optical stellar image using a real-time phase-correction system: initial results Astrophys. J. 211 463–468 Occurrence Handle1977ApJ...211..463M

    ADS  Google Scholar 

  10. J.W. Hardy (1978) ArticleTitleActive optics: a new technology for the control of light Proc. IEEE 66 651–697 Occurrence Handle10.1109/PROC.1978.10992 Occurrence Handle1978IEEEP..66..651H

    Article  ADS  Google Scholar 

  11. T.R. O’Meara (1977) ArticleTitleThe multi-dither principle in adaptive optics J. Opt. Soc. Am. 67 306–315 Occurrence Handle1977OSAJ...67..306O

    ADS  Google Scholar 

  12. J.E. Pearson S. Hansen (1977) ArticleTitleExperimental studies of a deformable-mirror adaptive optical system J. Opt. Soc. Am. 67 325–333 Occurrence Handle1977OSAJ...67..325P

    ADS  Google Scholar 

  13. M.A. Vorontsov G.W. Carhart J.C. Ricklin (1997) ArticleTitleAdaptive phase-distortion correction based on parallel gradient-descent optimization Opt. Lett. 22 907–909 Occurrence Handle1997OptL...22..907V

    ADS  Google Scholar 

  14. M.A. Vorontsov V.P. Sivokon (1998) ArticleTitleStochastic parallel-gradient-descent technique for high-resolution wave-front phase-distortion correction J. Opt. Soc. Am. A 15 2745–2758 Occurrence Handle1998OSAJ...15.2745V

    ADS  Google Scholar 

  15. J.C. Spall, Introduction to Stochastic Search and Optimization (Wiley, Hoboken, NJ, 2003).

  16. R.T. Edward, M. Cohen, G. Cauwenberghs, M.A. Vorontsov, and G.W. Carhart, “‘Analog VLSI parallel stochastic optimization for adaptive optics,” in Learning on Silicon, G. Cauwenberghs and M.A. Bayoumi, eds., (Kluwer Academic, Boston, 1999), Chap. 16, pp. 359-382.

  17. T.G. Bifano, J.A. Perreault, P.A. Bierden, and C.E. Dimas, ”Micromachined deformable mirrors for adaptive optics,” InHigh-Resolution Wavefront Control: Methods, Devices, and Applications IV, J.D. Gonglewski, M.A. Vorontsov, M.T. Gruneisen, S.R. Restaino, and R.K. Tyson, eds., Proc. SPIE 4825, 10-13 (2002).

  18. M.A. Vorontsov, G.W. Carhart, J.W. Gowens II, and J.C. Ricklin, “Adaptive correction of wave-front phase distortions in a free-space laser communication: system and method,” Patent pending.

  19. M.A. Vorontsov, G.W. Carhart, L.A. Beresnev, and J.W. Gowens II, “Adaptive WDM free-space laser communication system: low-order aberration compensation experiments,” presented at the International Symposium on Optical Science and Technology, Denver, Colorado, Conference 5550 “Free-Space Laser Communications IV,” 2-6 August 2004.

  20. M.A. Vorontsov, G.W. Carhart, M. Banta, T. Weyrauch, J. Gowens II, and J.C. Carrano, “Atmospheric laser optics testbed (A$\underline{~}$LOT): atmospheric propagation characterization, beam control and imaging results,” In Advanced Wavefront Control: Methods, Devices, and Applications, J.D. Gonglewski, M.A. Vorontsov, and M.T. Gruneisen, eds., Proc. SPIE 5162, 37-48 (2003).

  21. M.E. Gravecha, A.S. Gurvich, S.S. Kashkarov, and V.L.V. Pokasov, “Similarity relations and their experimental verification for strong intensity fluctuations of laser radiation,” in Laser Beam Propagation in the Atmosphere, J. Strohbehn, ed., (Springer, New York, 1978).

  22. L.C. Andrews, R.L. Phillips, and C.Y. Hopen, Laser Beam Scintillation with Applications (SPIE Press, Bellingham, WA, 2001).

  23. Y.A. Kravtsov (1993) ArticleTitleNew effects in wave propagation and scattering in random media (a mini review) Appl. Opt. 32 2681–2691 Occurrence Handle1993ApOpt..32.2681K Occurrence Handle10.1364/AO.32.002681

    Article  ADS  Google Scholar 

  24. M.A. Vorontsov G.W. Carhart M. Cohen G. Cauwenberghs (2000) ArticleTitleAdaptive optics based on analog parallel stochastic optimization: analysis and experimental demonstration J. Opt. Soc. Am. A 17 1440–1453 Occurrence Handle2000OSAJ...17.1440V

    ADS  Google Scholar 

  25. T. Weyrauch M.A. Vorontsov T.G. Bifano J.A. Hammer M. Cohen G. Cauwenberghs (2001) ArticleTitleMicroscale adaptive optics: wave-front control with a $\mu$-mirror array and a VLSI stochastic gradient descent controller Appl. Opt. 40 4243–4253 Occurrence Handle2001ApOpt..40.4243W

    ADS  Google Scholar 

  26. T. Weyrauch M.A. Vorontsov (2002) ArticleTitleDynamic wave-front distortion compensation with a 134-control-channel submillisecond adaptive system Opt. Lett. 27 751–753 Occurrence Handle2002OptL...27..751W

    ADS  Google Scholar 

  27. T.G. Bifano J. Perrault R. Krishnamoorthy Mali M.N. Horenstein (1999) ArticleTitleMicroelectromechanical deformable mirrors IEEE J. Sel. Top. Quantum Electron. 5 83–89

    Google Scholar 

  28. J.C. Ricklin F.M. Davidson (2003) ArticleTitleAtmospheric optical communication with a Gaussian Schell beam J. Opt. Soc. Am. A 20 856–866 Occurrence Handle2003OSAJ...20..856R

    ADS  Google Scholar 

  29. T. Weyrauch and M.A. Vorontsov, “Atmospheric compensation with a multiconjugate (piston-MEMS/modal DM) adaptive system,” In Target-in-the-Loop: Atmospheric Tracking, Imaging and Compensation, M.T. Valley and M.A. Vorontsov, eds., Proc. SPIE 5552, 73-84 (2004).

Download references

Author information

Authors and Affiliations

  1. Intelligent Optics Laboratory, Institute for Systems Research, University of Maryland, A.V. Williams Bldg., Mail Stop 1103, College Park, Maryland 20742, USA

    Thomas Weyrauch & Mikhail A. Vorontsov

  2. Computational and Information Sciences Directorate, U.S. Army Research Laboratory, 2800 Powder Mill Road, Adelphi, Maryland 20783, USA

    Mikhail A. Vorontsov

Authors
  1. Thomas Weyrauch
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Mikhail A. Vorontsov
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding authors

Correspondence to Thomas Weyrauch or Mikhail A. Vorontsov.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Weyrauch, T., Vorontsov, M. Free-space laser communications with adaptive optics: Atmospheric compensation experiments. J Optic Comm Rep 1, 355–379 (2004). https://doi.org/10.1007/s10297-005-0033-5

Download citation

  • Issue Date:

  • DOI: https://doi.org/10.1007/s10297-005-0033-5

Keywords

Search

Navigation