Improving system performance by using adaptive optics and aperture averaging for laser communications in oceanic...

Area of Science:

• Optical Physics
• Ocean Optics
• Laser Communications

Background:

• Oceanic turbulence significantly distorts laser beams, impacting direct detection systems.
• Adaptive optics (AO) offers a potential solution for wavefront correction in turbulent media.

Purpose of the Study:

• To theoretically evaluate the effectiveness of adaptive optics in correcting Gaussian beams distorted by oceanic turbulence.
• To determine the impact of AO on direct detection system performance using aperture-averaged scintillation as a key metric.

Main Methods:

• Modeled AO as the perfect removal of Zernike modes from an aberrated wavefront.
• Analyzed Gaussian beam propagation through simulated oceanic turbulence.
• Quantified performance using aperture-averaged scintillation for various numbers of corrected Zernike modes and transceiver aperture sizes.

Main Results:

• Adaptive optics significantly reduces scintillation, improving system performance.
• A reduction in scintillation by a factor of approximately 7 was observed when 15 Zernike modes were corrected.
• Optimal transceiver aperture size, capturing 4-5 turbulence-induced speckles, is crucial for maximizing AO effectiveness.

Conclusions:

• Adaptive optics is highly effective in mitigating the detrimental effects of oceanic turbulence on Gaussian beams.
• The performance gains are maximized when the transceiver aperture is appropriately sized relative to the turbulence characteristics.
• AO holds significant promise for enhancing the reliability of laser communication links operating in oceanic environments.