Article
Physics, Multidisciplinary
Omer F. Sayan, Hamza Gercekcioglu, Yahya Baykal
Summary: The scintillation index of multimode laser beams used in communication systems in weak atmospheric turbulent medium is examined using the Rytov method. The on-axis scintillation index is analyzed in relation to source size, propagation distance, and zenith angle for vertical links. The study finds that in general, multimode laser beams have larger scintillation noise compared to Gaussian laser beams. However, for specific parameters and at a downlink distance of 700 km, a multimode beam with larger mode content is found to have slightly smaller scintillations.
WAVES IN RANDOM AND COMPLEX MEDIA
(2022)
Article
Physics, Multidisciplinary
Mert Bayraktar
Summary: This study presents the scintillation performance of Weber beam propagating in atmospheric turbulence, showing that it has a lower scintillation index compared to spherical wave and Gaussian beam. Mitigation of scintillation is possible by generating Weber beams with more and smaller intensities, and the outputs of this study are anticipated to be used by communication system designers.
Article
Optics
Wenchen Li, Yijun Jiang, Wanwang Fu, Shichen Wu, Mi Lia
Summary: The atmospheric intensity scintillation effect deteriorates the communication quality of space chaos laser communication. The research analyzed the effect of internal and external mismatches induced by intensity scintillation on bit error rate (BER) in the space downlink chaos laser communication system. The results demonstrate that BER worsens with the effect of intensity scintillation, and internal mismatch has a greater impact on BER than external mismatch. These findings are valuable for designing practical space chaos laser communication systems with optimal performance.
OPTICAL ENGINEERING
(2022)
Article
Optics
Ya-qing Li, Li-guo Wang, Lei Gong, Qian Wang
Summary: Echo characteristics of plane and spherical waves reflected from a rough target in atmospheric turbulence were studied based on the extended Huygens-Fresnel principle. The intensity fluctuation caused by turbulence was found to decrease with increasing target size. It was also observed that under weak turbulence, log-amplitude fluctuations were the main factor affecting the second-order statistical properties of the received beam intensity.
Article
Acoustics
Andrea P. C. Bresciani, Julien Maillard, Leandro D. de Santana
Summary: This paper proposes a physics-based formulation to model amplitude and phase fluctuations of sound propagating in a turbulent atmosphere. The method is applicable to slanted and vertical propagation, and can simulate elevated noise sources such as aircraft, drones, and wind turbines. Two applications with audio files demonstrate the applicability of this method to tonal and broadband noise.
JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA
(2023)
Article
Optics
Xiangyuan Liu, Rui He, Huojiao Sun, Dandan Liu, Hao Yuan, Ke Tang
Summary: This study deduces the generalized scintillation index and plane wave structure function of the plane wave based on the modified non-Kolmogorov power spectrum of atmospheric refractive index. The fluctuation of atmospheric density due to thermal blooming is analyzed, and the thermal phase screening and intensity distribution of six beams in thermal blooming are simulated. The numerical simulation of the six-beam combination under atmospheric turbulence and thermal blooming is conducted, and parameters such as the equivalent radius, power in the bucket, Strehl ratio, and peak intensity are obtained. Results show that pulse beam combination parameters decrease with an increase in the power spectrum index alpha, except for the equivalent radius which operates in reverse, and short pulse durations can reduce thermal blooming. Laser of short duration cannot generate high ring energy on the target.
Article
Chemistry, Analytical
Yuqing Lu, Jiandong Mao, Yingnan Zhang, Hu Zhao, Chunyan Zhou, Xin Gong, Qiang Wang, Yi Zhang
Summary: Based on the residual turbulent scintillation theory, the Mie-scattering lidar system is used to measure the intensity of atmospheric turbulence. Through numerical simulation and calculation methods, the system parameters are evaluated and optimized, resulting in consistent atmospheric turbulence profiles with the input model.
Article
Optics
Yousef K. Chahine, Adam C. Wroblewski, John E. Malowicki, Joseph M. Flatico, Gunnar Ristroph, Alex Hsia, Rani Megally, Adam Resnick
Summary: This study presents an analysis of optical scintillation and fade on long slant-path atmospheric channels through a comparison between wave-optics-based numerical simulations and experimental flight data. The simulated power fluctuations, including power spectral density, fade probability, and mean fade time, were found to be in good agreement with measurements taken at slant-path distances ranging from 60 to 113 km and aircraft speeds up to 70 m/s.
OPTICAL ENGINEERING
(2021)
Article
Engineering, Electrical & Electronic
Mert Bayraktar, Salma Chib, Abdelmajid Belafhal
Summary: In this article, we investigate the scintillation and bit error rate performance of mirrored Bessel beams in turbulent atmosphere, using numerical modeling. Scintillation is found to be a crucial factor in optical wireless applications, and reducing it improves system performance. Results show that increasing the beam order to three can decrease scintillation under strong turbulence. Additionally, the argument of the Bessel beam has a more dominant role than the beam order in moderate turbulence. Mirroring also provides a slight advantage in terms of bit error rate. These findings are valuable for optical link designers.
OPTICAL AND QUANTUM ELECTRONICS
(2023)
Article
Engineering, Multidisciplinary
Wenzheng Liu, Cong Zhang, Fajie Duan, Xiao Fu, Ruijia Bao, Ming Yan
Summary: A method for noise attenuation of straightness measurement based on laser collimation was proposed to address the issue of atmospheric turbulence interference. The turbulence shield effectively reduced the impact of atmospheric turbulence on the measurement results, leading to improved accuracy and stability of the straightness measurement. Experimental results showed a significant decrease in standard deviations of straightness noise, with the effectiveness of the turbulence shield validated through simulations.
Article
Optics
Victor Kornilov, Boris Safonov, Matwey Kornilov
Summary: The development of new techniques in characterizing atmospheric optical turbulence has become a recent research focus, with the introduction of a dimensionless Fresnel filter for approximating polychromatic weighting functions. The study also explores matching conditions for weighting functions in different apertures, as well as the application of linear digital filters to scintillation signals. Main limitations of this approach, such as finite pixel size, aliasing, and finite image detector size, are discussed.
JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION
(2021)
Article
Telecommunications
Mert Bayraktar
Summary: This paper investigates the characteristics of Lommel beams, comparing their scintillation index to Gaussian beams and evaluating their performance in terms of bit error rate under weak turbulent and low signal to noise ratio conditions. It is found that Lommel beams exhibit lower scintillation indexes than Gaussian beams and outperform them in terms of bit error rate.
WIRELESS PERSONAL COMMUNICATIONS
(2022)
Article
Optics
Fei Wang, Han Lv, Yahong Chen, Yangjian Cai, Olga Korotkova
Summary: The study compares the equivalence and differences among three modal representation methods (CMR, PMR, RMR) for the Gaussian Schell-model (GSM) source class. Results show that for accurate reconstruction of CSD of a generic GSM source, CMR method requires superposition of the least number of modes, followed by PMR and then by RMR. The methods become equivalent with a sufficiently large number of modes, but limited to the second-order statistics of the source, while fourth-order statistics are quite different.
Article
Optics
Xiaoxin Zhou, Zeyu Zhou, Xiuhua Yuan
Summary: This paper investigates a new class of non-uniformly correlated flat-topped beams called convex partially coherent flat-topped (CPCFT) beams, and found that they self-focus during propagation, resulting in larger on-axis intensity and smaller scintillation compared to other types of beams. The properties of CPCFT beams make them effective for improving the mean signal-to-noise ratio (SNR) and reducing the mean bit-error rate (BER), and turbulence-induced degradation can be significantly reduced under certain circumstances.
OPTICS COMMUNICATIONS
(2021)
Article
Optics
Lijuan Zhang, Xue Tian, Yutong Jiang, Xingxin Li, Zhiyi Li, Dongming Li, Songtao Zhang
Summary: This paper proposes a deep neural network to enhance image clarity under strong turbulence, mitigating the effects of turbulence on the image.