FGDFDDD

1. Atmospheric aberrations in coherent laser systems Snowmass, July 12, 2007 Aniceto Belmonte [email_address]

2. Atmospheric Optical Systems

5. Atmospheric Effects on Received Signal WIDE-BAND SIGNAL-TO-NOISE RATIO PHASE DISTORTION BEAM WANDER BEAM SPREADING SCINTILLATION RECEIVED POWER UNCERTAINTY RECEIVED POWER LEVEL SENSITIVITY LINK QUALITY SIGNAL RELATIVE ERROR

6. Available Techniques !? Rytov Simulations Asymptotic Heuristic ?

8. Receiver Plane Formulation LO Beam Receiver Transmitted Beam i Reflected Beam Scatters Turbulence

9. Target Plane Formulation Receiver Transmitted Beam i BPLO Scatters LO Beam

10. Simulated Performance: Monostatic 0 1000 2000 3000 4000 5000 -6 -4 -2 0 2 4 Coherent Power Gain [dB] Lidar Range [m] C n 2 = 10 -12 m -2/3 λ = 2 μ m C n 2 = 10 -13 m -2/3

11. Simulated Performance: Bistatic T BPLO 0 1000 2000 3000 4000 5000 -8 -6 -4 -2 0 Lidar Range [m] Coherent Power Gain [dB] -10 C n 2 = 10 -12 m -2/3 λ = 2 μ m C n 2 = 10 -13 m -2/3

12. Misalignment Effects 0 500 1000 1500 2000 2500 3000 -16 -12 -8 -4 0 4 Coherent Power Gain [dB] Monostatic Bistatic 10 μ rad 20 μ rad 30 μ rad 40 μ rad D=36 cm C n 2 = 10 -12 m -2/3 λ = 2 μ m Range [m] θ 0 500 1000 1500 2000 2500 3000 -20 -15 -10 -5 0 5 Range [m] Monostatic Bistatic D= 9 cm Coherent Power Gain [dB]

13. Coherent Power Fluctuations 0 0.1 0.2 0.3 0.4 0.5 0.6 Strong C n 2 Coherent Power Standard Deviation 0 1000 2000 3000 4000 5000 Altitude [m] 0 0.1 0.2 0.3 0.4 0.5 Coherent Power Standard Deviation 30 ° 60 ° 90 ° (Zenith) Moderate C n 2 λ = 2  m 0 1000 2000 3000 4000 5000

14. Uncertainty Temporal Averaging 10 0 10 1 10 2 10 3 10 4 10 -3 10 -2 10 -1 10 0 10 1 N -1/2 V = 10 m/s R = 5 km Pulses Averaged 1 kHz 5 kHz 10 kHz C n 2 = 10 -13 m -2/3 λ = 2  m 10 -3 10 -2 10 -1 10 0 10 1 Normalized Standard Deviation N -1/2 10 0 10 1 10 2 10 3 10 4 Pulses Averaged R = 3 km C n 2 = 10 -12 m -2/3

17. APERTURE INTEGRATOR/ARRAYS PHASE COMPENSATED RECEIVERS RECIPROCITY POINTING ATMOSPHERIC COMPENSATION TECHNIQUES PHASE DISTORTION BEAM WANDER BEAM SPREADING SCINTILLATION ATMOSPHERIC EFFECTS ON RECEIVED SIGNAL DIRECT DETECTION GROUND, DOWNLINK DIRECT, HETERODYNE GROUND, DOWNLINK DIRECT, HETERODYNE GROUND, DOWN/UP LINKS Atmospheric Compensation Techniques

19. Atmospheric Compensation Needs in FSO Detector-plane Intensity Distributions

20. Adaptive Optics in Direct-Detection FSO Transmitter High Transmission Bandwidth Any Coding Scheme Horizontal/Slant Line-of-Sight Path Near and Far Field Deployment Distance Any Divergence Angle Near IR/Visible Wavelength Any Optical Power Medium Low (Day Time) Atmospheric Seeing High (Day Time) Solar Background Any Scintillation Any Visibility Receiver Single/Multiaperture Reception Diversity Small (APD) Detector Active Area Small (<1 mrad) Receiver Field of View >10 cm Receive Lens Diameter Any Receiver Sensitivity

21. FSO Coherent Power Gain 0 10 20 30 40 50 60 70 80 0 2 4 6 8 10 12 14 Modes Removed C n 2 = 10 -13 m -2/3 R = 3 k m 0 10 20 30 40 50 60 70 80 0 2 4 6 8 10 Modes Removed Coherent Power Gain (dB) C n 2 = 10 -14 m -2/3 λ = 1.55 μ m D=30 cm D=20 cm D=10 cm

25. Blind (Free-Model) Compensation LO Beam Receiver Transmitted Beam i Reflected Beam Scatters Controller

28. Coherent Power as Quality Metric 0 10 20 30 40 50 20 22 24 26 28 Overlap Integral (Coherent Power) Evolution Iteration Number Quality Metric 0 10 20 30 40 50 -0.4 -0.2 0 0.2 0.4 Quality Metric Gradient 0 1000 2000 3000 4000 5000 6000 7000 16 18 20 22 24 26 28 30 Range [m] Overlap Integral Overlap Integral (Coherent Power) Range Dependency

29. LO Control Wavefront 0 5 10 15 20 25 -15 -10 -5 0 5 10 Zernike Order Energy [dB]] Defocus Astigmatism Coma Spherical Aberration Distortion

30. Beam Projection

32. Coherent Power Gain vs Elevation Angle 0 10 20 30 40 50 0 1000 2000 3000 4000 5000 Coherent Power Gain [%] Altitude [m] Moderate C n 2 30 ° 45 ° 60 ° λ = 1  m 90 ° (Zenith) D = 40 cm 0 5 10 15 20 25 Coherent Power Gain [%] Strong C n 2 0 1000 2000 3000 4000 5000

33. Coherent Power Gain 0 10 20 30 40 50 0 1000 2000 3000 4000 5000 Coherent Power Gain [%] Altitude [m] Moderate C n 2 30 ° 45 ° 60 ° λ = 1  m 90 ° (Zenith) D = 20 cm 0 5 10 15 20 25 0 1000 2000 3000 4000 5000 Coherent Power Gain [%] Strong C n 2

34. Coherent Power Gain 0 5 10 15 20 25 0 1000 2000 3000 4000 5000 Coherent Power Gain [%] Altitude [m] Moderate C n 2 30 ° 45 ° 60 ° λ = 1  m 90 ° (Zenith) D = 10 cm 0 5 10 15 20 25 0 1000 2000 3000 4000 5000 Coherent Power Gain [%] Strong C n 2

35. Coherent Power Gain vs Aperture Size 0 10 20 30 40 50 0 1000 2000 3000 4000 5000 Coherent Power Gain [%] Altitude [m] Moderate C n 2 0 10 20 30 40 50 0 1000 2000 3000 4000 5000 Coherent Power Gain [%] Strong C n 2 λ = 1  m D = 10 cm θ = 90° (Zenith) D = 20 cm D = 40 cm

36. 0 10 20 30 40 50 0 1000 2000 3000 4000 5000 Coherent Power Gain [%] Altitude [m] Moderate C n 2 0 10 20 30 40 50 0 1000 2000 3000 4000 5000 Coherent Power Gain [%] λ = 1  m D = 10 cm θ = 45° D = 20 cm D = 40 cm Strong C n 2 Coherent Power Gain

37. Misalignment Compensation 0 5 10 15 0 1000 2000 3000 4000 5000 Coherent Power Gain [dB] Moderate C n 2 λ = 1  m D = 20 cm 90° (Zenith) 60° 30° Misalignment 20 μ m 0 5 10 15 0 1000 2000 3000 4000 5000 Coherent Power Gain [dB] Altitude [m] Moderate C n 2 Misalignment 20 μ m λ = 1  m D = 10 cm θ = 90° (Zenith) D = 20 cm D = 40 cm

38. Misalignment Compensation 0 5 10 15 20 0 1000 2000 3000 4000 5000 Coherent Power Gain [dB] Altitude [m] 30 μ m Moderate C n 2 λ = 1  m D = 20 cm θ = 90° (Zenith) 20 μ m 10 μ m 5 μ m