Abstract

The detection and processing of laser communication signals are affected by the fading induced onto these signals by atmospheric turbulence. One method of reducing this fading is to use an array of detectors in which each of the detector outputs are added together coherently. We present experimental verification and theory of a 1.06 μm eight-element coherent receiver used to mitigate the effects of fading over a 1-km outdoor range. The carrier-to-noise ratio (CNR) was measured on a single channel and was then compared with the CNR obtained from the coherent sum of the eight channels. The increase of the mean CNR for the coherent sum as compared with a single aperture was observed proportional to the number of the apertures under different conditions of atmospheric turbulence. The measured mean CNR gain fitted the theoretical prediction well when the laser intensity fluctuations followed the gamma distribution.

© 1998 Optical Society of America

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References

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  1. L. C. Andrews, R. L. Phillips, P. T. Yu, “Optical scintillations and fade statistics for a satellite-communication system,” Appl. Opt. 34, 7742–7751 (1995).
    [CrossRef] [PubMed]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef] [PubMed]
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1996 (2)

1995 (1)

1994 (1)

1990 (1)

T. Day, A. D. Farinas, R. L. Byer, “Demonstration of a low bandwidth 1.06 mm optical phase-locked loop for coherent homodyne communication,” IEEE Photon. Technol. Lett. 2, 294–296 (1990).
[CrossRef]

1988 (1)

1980 (1)

D. A. Jackson, R. Priest, A. Dandridge, A. B. Tveten, “Elimination of drift in a single-mode optical fiber interferometer using a piezoelectrically stretched coiled fiber,” Appl. Opt. 19, 970–972 (1980).
[CrossRef]

1976 (1)

1967 (1)

D. L. Fried, “Optical heterodyne detection of an atmospherically distorted signal wave front,” Proc. IEEE 55, 57–67 (1967).
[CrossRef]

1965 (1)

L. H. Enloe, J. L. Rodda, “Laser phase-locked loop,” Proc. IEEE 53, 165–166 (1965).
[CrossRef]

Andrews, L. C.

L. C. Andrews, R. L. Phillips, P. T. Yu, “Optical scintillations and fade statistics for a satellite-communication system,” Appl. Opt. 34, 7742–7751 (1995).
[CrossRef] [PubMed]

L. C. Andrews, D. E. Kelly, R. L. Phillips, A. R. Weeks, J. Harvey, J. Xu, C. Gagge, A. Notash, G. Luvera, G. Sellar, “Carrier-to-noise ratio for an equal-gain coherent laser radar receiver array system: theory and experiment.” in Optics in Atmospheric Propagation and Adaptive Systems II, A. Kohnle, A. D. Devir, eds., Proc. SPIE3219, 84–92 (1997).
[CrossRef]

Byer, R. L.

T. Day, A. D. Farinas, R. L. Byer, “Demonstration of a low bandwidth 1.06 mm optical phase-locked loop for coherent homodyne communication,” IEEE Photon. Technol. Lett. 2, 294–296 (1990).
[CrossRef]

Castellanos, D. C.

Cheng, A. P.

Costello, T. P.

Dandridge, A.

D. A. Jackson, R. Priest, A. Dandridge, A. B. Tveten, “Elimination of drift in a single-mode optical fiber interferometer using a piezoelectrically stretched coiled fiber,” Appl. Opt. 19, 970–972 (1980).
[CrossRef]

Day, T.

T. Day, A. D. Farinas, R. L. Byer, “Demonstration of a low bandwidth 1.06 mm optical phase-locked loop for coherent homodyne communication,” IEEE Photon. Technol. Lett. 2, 294–296 (1990).
[CrossRef]

Enloe, L. H.

L. H. Enloe, J. L. Rodda, “Laser phase-locked loop,” Proc. IEEE 53, 165–166 (1965).
[CrossRef]

Farinas, A. D.

T. Day, A. D. Farinas, R. L. Byer, “Demonstration of a low bandwidth 1.06 mm optical phase-locked loop for coherent homodyne communication,” IEEE Photon. Technol. Lett. 2, 294–296 (1990).
[CrossRef]

Fink, D.

Fried, D. L.

D. L. Fried, “Optical heterodyne detection of an atmospherically distorted signal wave front,” Proc. IEEE 55, 57–67 (1967).
[CrossRef]

Gagge, C.

L. C. Andrews, D. E. Kelly, R. L. Phillips, A. R. Weeks, J. Harvey, J. Xu, C. Gagge, A. Notash, G. Luvera, G. Sellar, “Carrier-to-noise ratio for an equal-gain coherent laser radar receiver array system: theory and experiment.” in Optics in Atmospheric Propagation and Adaptive Systems II, A. Kohnle, A. D. Devir, eds., Proc. SPIE3219, 84–92 (1997).
[CrossRef]

Gatt, P.

Harvey, J.

L. C. Andrews, D. E. Kelly, R. L. Phillips, A. R. Weeks, J. Harvey, J. Xu, C. Gagge, A. Notash, G. Luvera, G. Sellar, “Carrier-to-noise ratio for an equal-gain coherent laser radar receiver array system: theory and experiment.” in Optics in Atmospheric Propagation and Adaptive Systems II, A. Kohnle, A. D. Devir, eds., Proc. SPIE3219, 84–92 (1997).
[CrossRef]

Heimmermann, D. A.

Jackson, D. A.

D. A. Jackson, R. Priest, A. Dandridge, A. B. Tveten, “Elimination of drift in a single-mode optical fiber interferometer using a piezoelectrically stretched coiled fiber,” Appl. Opt. 19, 970–972 (1980).
[CrossRef]

Jakes, W. C.

W. C. Jakes, Microwave Mobile Communications (IEEE, New York, 1974).

Jutila, J. M.

J. M. Jutila, “Wireless laser networking,”IEEE Telecommun.37–40 (1996).

Kane, J. T.

Kelly, D. E.

L. C. Andrews, D. E. Kelly, R. L. Phillips, A. R. Weeks, J. Harvey, J. Xu, C. Gagge, A. Notash, G. Luvera, G. Sellar, “Carrier-to-noise ratio for an equal-gain coherent laser radar receiver array system: theory and experiment.” in Optics in Atmospheric Propagation and Adaptive Systems II, A. Kohnle, A. D. Devir, eds., Proc. SPIE3219, 84–92 (1997).
[CrossRef]

Kudielka, K. H.

Leeb, W. R.

Luvera, G.

L. C. Andrews, D. E. Kelly, R. L. Phillips, A. R. Weeks, J. Harvey, J. Xu, C. Gagge, A. Notash, G. Luvera, G. Sellar, “Carrier-to-noise ratio for an equal-gain coherent laser radar receiver array system: theory and experiment.” in Optics in Atmospheric Propagation and Adaptive Systems II, A. Kohnle, A. D. Devir, eds., Proc. SPIE3219, 84–92 (1997).
[CrossRef]

Neubert, W. M.

Notash, A.

L. C. Andrews, D. E. Kelly, R. L. Phillips, A. R. Weeks, J. Harvey, J. Xu, C. Gagge, A. Notash, G. Luvera, G. Sellar, “Carrier-to-noise ratio for an equal-gain coherent laser radar receiver array system: theory and experiment.” in Optics in Atmospheric Propagation and Adaptive Systems II, A. Kohnle, A. D. Devir, eds., Proc. SPIE3219, 84–92 (1997).
[CrossRef]

Parson, J. D.

J. D. Parson, “Diversity techniques in communications receivers,” in Advanced Signal Processing, D. A. Creasey, ed. (Peregrinus, London, 1985).
[CrossRef]

Phillips, R. L.

L. C. Andrews, R. L. Phillips, P. T. Yu, “Optical scintillations and fade statistics for a satellite-communication system,” Appl. Opt. 34, 7742–7751 (1995).
[CrossRef] [PubMed]

L. C. Andrews, D. E. Kelly, R. L. Phillips, A. R. Weeks, J. Harvey, J. Xu, C. Gagge, A. Notash, G. Luvera, G. Sellar, “Carrier-to-noise ratio for an equal-gain coherent laser radar receiver array system: theory and experiment.” in Optics in Atmospheric Propagation and Adaptive Systems II, A. Kohnle, A. D. Devir, eds., Proc. SPIE3219, 84–92 (1997).
[CrossRef]

Priest, R.

D. A. Jackson, R. Priest, A. Dandridge, A. B. Tveten, “Elimination of drift in a single-mode optical fiber interferometer using a piezoelectrically stretched coiled fiber,” Appl. Opt. 19, 970–972 (1980).
[CrossRef]

Rodda, J. L.

L. H. Enloe, J. L. Rodda, “Laser phase-locked loop,” Proc. IEEE 53, 165–166 (1965).
[CrossRef]

Scholtz, A. L.

Sellar, G.

L. C. Andrews, D. E. Kelly, R. L. Phillips, A. R. Weeks, J. Harvey, J. Xu, C. Gagge, A. Notash, G. Luvera, G. Sellar, “Carrier-to-noise ratio for an equal-gain coherent laser radar receiver array system: theory and experiment.” in Optics in Atmospheric Propagation and Adaptive Systems II, A. Kohnle, A. D. Devir, eds., Proc. SPIE3219, 84–92 (1997).
[CrossRef]

Stickley, C. M.

Tveten, A. B.

D. A. Jackson, R. Priest, A. Dandridge, A. B. Tveten, “Elimination of drift in a single-mode optical fiber interferometer using a piezoelectrically stretched coiled fiber,” Appl. Opt. 19, 970–972 (1980).
[CrossRef]

Vodopia, S. N.

Weeks, A. R.

P. Gatt, T. P. Costello, D. A. Heimmermann, D. C. Castellanos, A. R. Weeks, C. M. Stickley, “Coherent optical array receivers for the mitigation of atmospheric turbulence and speckle effects,” Appl. Opt. 35, 5999–6009 (1996).
[CrossRef] [PubMed]

L. C. Andrews, D. E. Kelly, R. L. Phillips, A. R. Weeks, J. Harvey, J. Xu, C. Gagge, A. Notash, G. Luvera, G. Sellar, “Carrier-to-noise ratio for an equal-gain coherent laser radar receiver array system: theory and experiment.” in Optics in Atmospheric Propagation and Adaptive Systems II, A. Kohnle, A. D. Devir, eds., Proc. SPIE3219, 84–92 (1997).
[CrossRef]

Xu, J.

L. C. Andrews, D. E. Kelly, R. L. Phillips, A. R. Weeks, J. Harvey, J. Xu, C. Gagge, A. Notash, G. Luvera, G. Sellar, “Carrier-to-noise ratio for an equal-gain coherent laser radar receiver array system: theory and experiment.” in Optics in Atmospheric Propagation and Adaptive Systems II, A. Kohnle, A. D. Devir, eds., Proc. SPIE3219, 84–92 (1997).
[CrossRef]

Yu, P. T.

Appl. Opt. (5)

IEEE Photon. Technol. Lett. (1)

T. Day, A. D. Farinas, R. L. Byer, “Demonstration of a low bandwidth 1.06 mm optical phase-locked loop for coherent homodyne communication,” IEEE Photon. Technol. Lett. 2, 294–296 (1990).
[CrossRef]

IEEE Telecommun. (1)

J. M. Jutila, “Wireless laser networking,”IEEE Telecommun.37–40 (1996).

Opt. Lett. (1)

Proc. IEEE (2)

L. H. Enloe, J. L. Rodda, “Laser phase-locked loop,” Proc. IEEE 53, 165–166 (1965).
[CrossRef]

D. L. Fried, “Optical heterodyne detection of an atmospherically distorted signal wave front,” Proc. IEEE 55, 57–67 (1967).
[CrossRef]

Other (3)

W. C. Jakes, Microwave Mobile Communications (IEEE, New York, 1974).

J. D. Parson, “Diversity techniques in communications receivers,” in Advanced Signal Processing, D. A. Creasey, ed. (Peregrinus, London, 1985).
[CrossRef]

L. C. Andrews, D. E. Kelly, R. L. Phillips, A. R. Weeks, J. Harvey, J. Xu, C. Gagge, A. Notash, G. Luvera, G. Sellar, “Carrier-to-noise ratio for an equal-gain coherent laser radar receiver array system: theory and experiment.” in Optics in Atmospheric Propagation and Adaptive Systems II, A. Kohnle, A. D. Devir, eds., Proc. SPIE3219, 84–92 (1997).
[CrossRef]

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Figures (5)

Fig. 1
Fig. 1

Schematic of the eight-aperture equal-gain coherent-detection system. AOM, acousto-optic modulator.

Fig. 2
Fig. 2

Block diagram of the sampling circuit. LP, low pass.

Fig. 3
Fig. 3

Mean CNR gain versus number of apertures for 200 m.

Fig. 4
Fig. 4

Mean CNR gain versus number of apertures for 500 m.

Fig. 5
Fig. 5

Mean CNR gain versus number of apertures for 1000 m.

Tables (4)

Tables Icon

Table 1 Measured Mean CNR Gain for 200 m

Tables Icon

Table 2 Normalized Moments of the Signal Intensities and Gamma Distribution

Tables Icon

Table 3 Measured Mean CNR Gain for 500 m

Tables Icon

Table 4 Measured Mean CNR Gain for 1000 m

Equations (18)

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s t = k = 1 M   a k s k t ,
s k t = 2 A sk A LO   cos ω s - ω LO t + ϕ k = 2 A sk A LO   cos Δ ω t + ϕ k ,
s t = k = 1 M   s k t = 2 A LO k = 1 M   A sk cos Δ ω t + ϕ r ,
A = k = 1 M   A sk .
CNR = A 2 2 NM = 1 2 NM k = 1 M   A sk 2 ,
CNR ¯ = 1 + M - 1 A s ¯ 2 A s 2 ¯ A s 2 ¯ 2 N ,
CNR ¯ gain = 1 + M - 1 A s ¯ 2 A s 2 ¯ .
CNR ¯ gain M = average   IF   carrier   power   M average   noise   power   M average   IF   carrier   power   1 average   noise   power   1 ,
CNR ¯ 1 = average   IF   carrier   power   1 average   noise   power   1 ,
I M = A sk 2 A LO 2 cos 2 Δ ω t + ϕ k = 1 2   I s I LO 1 + cos 2 Δ ω t + ϕ k ,
I s n ¯ I s ¯ n = 1 m k = 1 m   I k n 1 m k = 1 m   I k n ,
CNR ¯ = 0.081 + 0.780 M .
CNR ¯ gain - Γ = 1 + M - 1 α Γ 1 2 + α Γ α 2 ,
α = 1 I 2 ¯ / I ¯ 2 - 1 ,
CNR ¯ gain - Γ = 0.428 + 0.572 M
CNR ¯ gain - Γ = 0.312 + 0.688 M
CNR ¯ = - 0.211 + 0.587 M ,
CNR ¯ = 0.076 + 0.580 M .

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