Performance of wavefront-sensorless adaptive optics using modal and zonal correction

Anzuola, Esdras; Segel, Max; Gładysz, Szymon; Stein, Karin

doi:10.1117/12.2241067

Cited by 12 publications

(17 citation statements)

References 14 publications

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“…Indirect wavefront sensing techniques have gained more scientific attention in the field of FSOC [13][14][15], mainly due to improvements associated with fast DMs, parallel processing, and efficient blind search algorithms [15]. These sensor-less techniques iteratively optimize the received power, updating the AO phase compensation system based on the analysis of a performance metric, which is generally power in the bucket.…”

Section: Introductionmentioning

confidence: 99%

“…Two different blind search approaches are usually considered. The zonal approach randomly changes the states of single DM actuators in searching for optimal power coupling; the modal approach shapes all actuators at once, following an orthogonal modal basis (e.g., Zernike polynomials) [15]. In general, indirect phase sensing benefits from simple optical setups, high power efficiency, and robustness against power scintillation.…”

Section: Introductionmentioning

confidence: 99%

“…Unfortunately, indirect wavefront sensing techniques also have limitations when dealing with laser propagation through the atmosphere. In particular, the short coherence time of the field fluctuations may overcome the correction capacity of iterative techniques, where usually hundreds of iterative measurements may be required [15]. Considering a typical LEO downlink, where coherence times of one millisecond are usual [16,17], unpractical control bandwidth above may be required.…”

Section: Introductionmentioning

confidence: 99%

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Intensity-based adaptive optics with sequential optimization for laser communications

Carrizo¹,

Calvo²,

Belmonte³

2018

Opt. Express

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Wavefront distortions of optical waves propagating through the turbulent atmosphere are responsible for phase and amplitude fluctuations, causing random fading in the signal coupled into single-mode optical fibers. Wavefront aberrations can be confronted, in principle, with adaptive optics technology that compensates the incoming optical signal by the phase conjugation principle and mitigates the likeliness of fading. However, real-time adaptive optics requires phase wavefront measurements, which are generally difficult under typical propagation conditions for communication scenarios. As an alternative to the conventional adaptive optics approach, here, we discuss a novel phase-retrieval technique that indirectly determines the unknown phase wavefront from focal-plane intensity measurements. The adaptation approach is based on sequential optimization of the speckle pattern in the focal plane and works by iteratively updating the phases of individual speckles to maximize the received power. We found in our analysis that this technique can compensate the distorted phasefront and increase the signal coupled with a significant reduction in the required number of iterations, resulting in a loop bandwidth utilization well within the capacity of commercially available deformable mirrors.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Intensity-based adaptive optics with sequential optimization for laser communications

Carrizo¹,

Calvo²,

Belmonte³

2018

Opt. Express

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“…Real-time systems, like those based on Shack-Hartmann wave-front sensor, are very efficient as long as the turbulence is weak-to-moderate [1]. For stronger turbulence conditions, scintillation and phase singularities limit its performance, and the wave-front correction may be better faced with iterative systems [2].…”

Section: Introductionmentioning

confidence: 99%

“…Overall, the available time for a phase wave-front correction can be rounded to 1 milliseconds [3,4]. Considering that existing iterative solutions need more than 100 iterations to converge to an optimum, we would require unpractical loop bandwidths on the order of 100 kHz [2,5]. An alternative is a hybrid system which combines real-time wavefront sensors to provide a system hot start, effectively reducing the number of iterations [6].…”

Section: Introductionmentioning

confidence: 99%

Proof of concept for adaptive sequential optimization of free-space communication receivers

2019

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In a down-link scenario, performance of laser satellite communications is limited due to atmospheric turbulence, which causes fluctuations in the intensity and the phase of the received signal leading to an increase in bit error probability. In principle, a single-aperture phase-compensated receiver, based on adaptive optics, can overcome atmospheric limitations by adaptive tracking and correction of atmospherically induced aberrations. However, under strong-turbulence situations, the effectiveness of traditional adaptive optics systems is severely compromised. We have developed an alternative intensity-based technique that corrects the wave-front by iteratively updating the phases of individual focal-plane speckles, maximizing the power coupled into a single-mode fiber. Here, we present the proof of concept for this method. We show how this technique improves the quality of the received signal by 4 dB gain with less than 60 power measurements under strong turbulence conditions.

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Introduction

2023

Optical Wireless Communication Theory and Technology

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Performance of wavefront-sensorless adaptive optics using modal and zonal correction

Cited by 12 publications

References 14 publications

Intensity-based adaptive optics with sequential optimization for laser communications

Intensity-based adaptive optics with sequential optimization for laser communications

Proof of concept for adaptive sequential optimization of free-space communication receivers

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