Numerical investigation of multichannel laser beam phase locking in turbulent atmosphere

Volkov, Mikhail V.; Гаранин, С. Г.; Starikov, F. A.

doi:10.1070/qe2015v045n12abeh015885

Cited by 6 publications

(3 citation statements)

References 14 publications

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“…For example, when d / r 0 = 1.5 the average Strehl ratio equals 0.29, but when d / r 0 = 0.5 the average Strehl ratio equals 0.74. Asymptotic calculation results presented in figure 1 quantitatively agree with the results obtained previously in [12] for the same Fried parameters. In current computations, the Fried parameter has been determined by wavefront analysis obtained using the von Kármán turbulence spectrum.…”

Section: Calculation Resultssupporting

confidence: 88%

“…In current computations, the Fried parameter has been determined by wavefront analysis obtained using the von Kármán turbulence spectrum. In this approach, the external scale of the turbulence is limited by a numerical domain half-width and corresponds to larger value of the Fried parameter in comparison with [12].…”

Section: Calculation Resultsmentioning

confidence: 99%

“…where N is the number of combined channels, α is the minimal number of needed iterations per channel for convergence of SPG algorithm equaled 2 iterations per channel [12]. Note one more that rather low values of wind velocity and Greenwood frequency taken in calculations do not affect the main derivations from the calculation results since they depend on the ν ph / ν G ratio only.…”

Section: Problem Statementmentioning

confidence: 99%

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Numerical investigation of dynamic coherent beam combining in turbulent atmosphere with taking into account the double-pass delay

Kuzikov

Volkov

Starikov

2022

28th International Symposium on Atmospheric and Ocean Optics: Atmospheric Physics

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The paper is devoted to numerical investigation of coherent beam combining of 7-channel laser radiation and its focusing on the remote receiver in dynamic turbulent medium using the two-step stochastic parallel gradient (SPG) algorithm with the double-pass delay included in the step time or in the temporal shift between steps. Dynamic turbulent medium has been modelled using one phase screen approximation based on the Taylor hypothesis. The spatial spectrum of turbulent distortions has corresponded to the von Kármán spectrum and has been characterized by the atmospheric coherence radius (the Fried parameter) r0. Combining efficiency has been estimated for various ratios of the aperture size d to r0 and ratios of the phasing frequency νph (reciprocal value of time interval required to achieve the Strehl ratio equaled 0.8 in the nonturbulent medium) to the Greenwood frequency νG. The requirements for d/r0 and νph / νG values have been determined, under which the SPG coherent beam combining with taking into account the double-pass delay provides the Strehl ratio level of ~0.7 or higher.

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Section: Calculation Resultssupporting

confidence: 88%

Section: Calculation Resultsmentioning

confidence: 99%

Section: Problem Statementmentioning

confidence: 99%

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Numerical investigation of dynamic coherent beam combining in turbulent atmosphere with taking into account the double-pass delay

Kuzikov

Volkov

Starikov

2022

28th International Symposium on Atmospheric and Ocean Optics: Atmospheric Physics

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Phasing of seven-channel fibre laser radiation with dynamic turbulent phase distortions using a stochastic parallel gradient algorithm at a bandwidth of 450 kHz

et al. 2020

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We have demonstrated an experimental setup for the coherent phasing of a seven-channel fibre laser system ( λ = 1064 nm) in a scheme comprising a master oscillator and a set of parallel amplifiers with lithium niobate-based fibre-optic phase modulators. Using a stochastic parallel gradient algorithm, an instrumental phase modulator control unit ensures a bandwidth of the system up to 450 kHz. The effectiveness of phasing of light transmitted through a turbulent medium with a characteristic time scale τ turb has been studied experimentally as a function of phasing time τ ph. The results demonstrate that the average Strehl ratio begins to rise at τ turb/τ ph ⩾ 2 and that the effectiveness of compensation for dynamic phase distortions in the beam propagation path rises sharply at τ turb/τ ph ≈ 20. For τ turb/τ ph ⩾ 30 – 40, the average Strehl ratio remains constant at the level reached.

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Phase combining of radiation from a two-channel explosively pumped photodissociation iodine laser with an SBS mirror

Гаранин¹,

Dolgopolov²,

Kachalin³

et al. 2022

Quantum Electron.

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A two-channel double-pass iodine explosively pumped photodissociation laser (EPPL) with an explosively pumped master oscillator (MO) and an SBS mirror is studied. The radiation source, determined by an aperture 6 mm in diameter, through which the radiation from MO enters the turbulent surface air path, is located at a distance of 2.5 km from the amplifier unit input. An SBS mirror with a kinoform raster of microlenses is used to compensate for the amplifier and path optical inhomogeneities and to match the phases in the EPPL channels. The energy and spatial characteristics of the EPPL output radiation are studied experimentally and numerically. Good agreement is obtained between the experimental and calculated distribution of the energy density of the output EPPL radiation in the plane of the MO aperture, which is a pattern of interference between the two channels. The maximum energy density in the aperture plane is by more than 4 times greater than in the case of a single-channel EPPL.

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Numerical investigation of multichannel laser beam phase locking in turbulent atmosphere

Cited by 6 publications

References 14 publications

Numerical investigation of dynamic coherent beam combining in turbulent atmosphere with taking into account the double-pass delay

Numerical investigation of dynamic coherent beam combining in turbulent atmosphere with taking into account the double-pass delay

Phasing of seven-channel fibre laser radiation with dynamic turbulent phase distortions using a stochastic parallel gradient algorithm at a bandwidth of 450 kHz

Phase combining of radiation from a two-channel explosively pumped photodissociation iodine laser with an SBS mirror

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