Practical calculation of the beam scintillation index based on the rigorous asymptotic propagation theory

Charnotskii, Mikhail; Baker, Gary J.

doi:10.1117/12.884632

Cited by 8 publications

(4 citation statements)

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“…However, the derivations are focused on the homogenous path (Ĉ 2 n z maintains constant); though they are applied for the inhomogenous path (Ĉ 2 n z varies with z), where σ 2 R is expressed as an integral function of C 2 n z [9], this approximation is not accurate. Recently, another asymptotic theory based method for investigating the moderate-to-strong turbulence has been proposed [23], which determines the moderate-to-strong region by mathematical interpolation between the rigorous asymptotes of the weak perturbation and strong scintillation theories. The advantage for this method is that it is applicable for both the homogenous path and the inhomogenous path, and the expression in [23] fits well with the rigorous results for weak and strong turbulence regions.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

“…Recently, another asymptotic theory based method for investigating the moderate-to-strong turbulence has been proposed [23], which determines the moderate-to-strong region by mathematical interpolation between the rigorous asymptotes of the weak perturbation and strong scintillation theories. The advantage for this method is that it is applicable for both the homogenous path and the inhomogenous path, and the expression in [23] fits well with the rigorous results for weak and strong turbulence regions. Although this approach lacks some physical explanations for the choices of the interpolation function and some key parameters, it provides a simple analytical approximation to bridge the gap between the weak and strong scintillation theories for practical calculations.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

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Atmospheric spectral model and theoretical expressions of irradiance scintillation index for optical wave propagating through moderate-to-strong non-Kolmogorov turbulence

et al. 2012

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A new atmospheric spectral model and expressions of irradiance scintillation index are derived theoretically for optical wave propagating through moderate-to-strong non-Kolmogorov turbulence. They are developed under Andrews' assumption that small-scale irradiance fluctuations are modulated by large-scale irradiance fluctuations of the wave, and the geometrical optics approximation is adopted for mathematical development. A wide range of turbulence strength is considered instead of a limited range for weak turbulence. The atmospheric spectral model has a spectral power law value in the range of 3 to 4 instead of the standard power law value of 11/3. Numerical calculations are conducted to analyze the influences of spectral power law and turbulence strength.

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Section: Conclusion and Discussionmentioning

confidence: 99%

Section: Conclusion and Discussionmentioning

confidence: 99%

Atmospheric spectral model and theoretical expressions of irradiance scintillation index for optical wave propagating through moderate-to-strong non-Kolmogorov turbulence

et al. 2012

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“…This effect can be minimized using, for example, aperture averaging, diversity techniques, adaptive optics, or some modulation techniques [ 35 ]. It also was shown that an operation at longer wavelengths allows for better transmission during turbulence [ 36 ]. However, strong turbulence causes comparable radiation attenuation for NIR, SWIR, and MWIR ranges.…”

Section: Methodsmentioning

confidence: 99%

Data Link with a High-Power Pulsed Quantum Cascade Laser Operating at the Wavelength of 4.5 µm

Mikołajczyk

2021

Sensors

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This article is a short study of the application of high-power quantum cascade lasers and photodetectors in medium-infrared optical wireless communications (OWC). The link range is mainly determined by the transmitted beam parameters and the performance of the light sensor. The light power and the photodetector noise directly determine the signal-to-noise power ratio. This ratio could be maximized in the case of minimizing the radiation losses caused by atmospheric attenuation. It can be obtained by applying both radiation sources and sensors operated in the medium infrared range decreasing the effects of absorption, scattering or scintillation, beam spreading, and beam wandering. The development of a new class of laser sources based on quantum cascade structures becomes a prospective alternative. Regarding the literature, there are descriptions of some preliminary research applying these lasers in data transmission. To provide a high data transfer rate, continuous wave (cw) lasers are commonly used. However, they are characterized by low power (a few tens of mWatts) limiting their link range. Also, only a few high-power pulsed lasers (a few hundreds of mWatts) were tested. Due to their limited pulse duty cycle, the obtained modulation bandwidth was lower than 1 MHz. The main goal of this study is to experimentally determine the capabilities of the currently developed state-of-the-art high-power pulsed quantum cascade (QC) lasers and photodetectors in OWC systems. Finally, the data link range using optical pulses of a QC laser of ~2 W, operated at the wavelength of ~4.5 µm, is discussed.

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“…(56) To summarize, mean irradiance for the extended medium is still described by Eq. (17) provided that C r is given in Eq. (55).…”

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confidence: 99%

Passive scintillometer: theory and field measurements

Charnotskii¹

2021

J. Opt. Soc. Am. A

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We propose design of a low-cost passive scintillometer that measures the strength of optical turbulence by analyzing scintillation in the image of a straight edge between the two areas of uniform, but distinct brightness. Two theoretical approaches to scintillations description are developed that are based on the phase screen and rigorous path integral propagation imaging models. Asymptotic analysis of both models leads to four distinctive imaging situations. We propose two uniform approximations that cover the most promising conclusion for the passive scintillometer applications. Both the strength of scintillation and the width of the area where scintillations exist can be used to estimate the turbulence strength. We present the results of the proof-of-concept experiment where images of the specifically made target were taken by a consumer grade camera equipped with a telephoto lens. We describe the image processing that separates the target characteristics from the turbulence scintillations. The spatial profiles of the image variances at three spectral bands and for several apertures were calculated. As was expected, scintillations are concentrated around the sharp edge and are absent at the uniformly bright parts of the target. Observed edge scintillation variances are within the theoretical limits, and provide reasonable estimates for the turbulence structure constant across the three spectral bands. However, the width of the scintillation area and dependence on the aperture are inconsistent with the thin lens imaging theory for larger apertures. We attribute this to the Additional bench tests on bar targets revealed that the camera and lens resolution are well below the nominal thin lens diffraction limit, and a different optical setup should be used in order to exploit the spatial distribution and aperture dependence of fluctuations.

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Practical calculation of the beam scintillation index based on the rigorous asymptotic propagation theory

Cited by 8 publications

References 1 publication

Atmospheric spectral model and theoretical expressions of irradiance scintillation index for optical wave propagating through moderate-to-strong non-Kolmogorov turbulence

Atmospheric spectral model and theoretical expressions of irradiance scintillation index for optical wave propagating through moderate-to-strong non-Kolmogorov turbulence

Data Link with a High-Power Pulsed Quantum Cascade Laser Operating at the Wavelength of 4.5 µm

Passive scintillometer: theory and field measurements

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