The performances of satellite-to-ground downlink optical communications over Gamma-Gamma distributed atmospheric turbulence are studied for a coherent detection receiving system with spatial diversity. Maximum ratio combining (MRC) and selection (SC) techniques considered as practical schemes to mitigate the turbulence. Bit-error rate (BER) binary phase-shift keying modulated outage probabilities analyzed compared SC diversity using analytical results MRC through an approximation method...

The linear canonical transform (LCT) plays an important role in many fields of optics and signal processing. Many properties for this are already known, however, the convolution theorems don't have elegance simplicity comparable to that Fourier (FT), which states two functions is product their transforms. purpose letter introduce a new structure LCT preserves theorem also easy implement designing filters. Some well-known results about FT domain, fractional (FRFT) domain shown be special...

Biofilm contributes significantly to bacterial persistence in endoscope channels. Enhanced cleaning methods capable of removing biofilm from all channels are required decrease infection risk patients. This head-to-head study compared cyclic build-up removal an automated channel cleaner (AECC) with standard manual according instructions for use (IFU) polytetrafluorethylene

To achieve real-time deep learning wavefront sensing (DLWFS) of dynamic random distortions induced by atmospheric turbulence, this study proposes an enhanced neural network (WFSNet) based on convolutional networks (CNN). We introduce a novel multi-objective architecture search (MNAS) method designed to attain Pareto optimality in terms error and floating-point operations (FLOPs) for the WFSNet. Utilizing EfficientNet-B0 prototypes, we propose WFSNet with which significantly reduces...

Based on weak fluctuation theory and the beam-wander model, bit-error rate of a ground-to-satellite laser uplink communication system is analyzed, in comparison with condition which beam wander not taken into account. Considering combined effect scintillation wander, optimum divergence angle transmitter radius for are researched. Numerical results show that both them increase increment total link margin transmitted wavelength. This work can benefit design.

In intersatellite optical communications it is important to obtain the most efficient performance of acquisition system with respect time for a given probability. this paper novel approach analytical optimization spatial presented as an alternative conventional Monte Carlo simulation. First, expression estimating mean (MAT) derived function desired probability, taking into account distribution satellite position, field uncertainty (FOU), beam divergence angle and dwell time. Accordingly,...

High power erbium-ytterbium co-doped fiber amplifier (EYDFA) has been radiated to the dose of 50 krad at rate 40 rad/s. Some key parameters have measured investigate radiation effect on EYDFA for space optical communication. Considering is big enough most low-dose environment, these experimental results will be a good reference inter-satellite communication designers.

An 11.8km optical link is established to examine the intensity fluctuation of laser beam transmission through atmosphere turbulence. Probability density function, fade statistic, and high-frequency spectrum are researched based on analysis experimental data collected in each season a year, including both weak strong cases. Finally, daily variation curve scintillation index given, compared with refractive-index structure parameter C(n) (2), which calculated from angle arrival. This work...

In the past decades, both increasing experimental evidences and some results of theoretical investigation on non-Kolmogorov turbulence have been reported. This has prompted study optical propagation in atmospheric turbulence. this paper, using a power spectrum which owns generalized law instead standard Kolmogorov value 11/3 amplitude factor constant 0.033, log-amplitude variances for Gaussian-beam wave are derived weak-fluctuation regime horizontal path. The analytic expressions obtained...

We first show that the bandlimited signals associated with linear canonical transform (LCT) form a reproducing kernel Hilbert space. An orthogonal basis for class of LCT is then proposed by use kernel, respect to which coordinates signal are actually values taken at certain instants time. Finally, nonuniform sampling theorem presented.

The performances of fiber-based free-space optical (FSO) communications over gamma-gamma distributed turbulence are studied for multiple aperture receiver systems. equal gain combining (EGC) technique is considered as a practical scheme to mitigate the atmospheric turbulence. Bit error rate (BER) binary-phase-shift-keying-modulated coherent detection derived and analyzed EGC diversity receptions through an approximation method. To show net system, BER compared with single monolithic system...

Efficient coupling of coherent plane waves into single-mode fibers is a key technology for free-space optical communication at 1550 nm. Here we deal with the influence random angular jitter on wave to fiber coupling. The expression mean-coupling efficiency in presence handled pupil plane. First, an analytical derived zero bias error case. Then was taken account. By minimizing penalty, optimum value design parameter beta fiber-coupled systems obtained. results obtained here will be useful...

Nowadays it has been accepted that the Kolmogorov model is not only possible turbulent one in atmosphere, which confirmed by increasing experimental evidences and some results of theoretical investigation. This prompted scientist community to study optical propagation non-Kolmogorov atmospheric turbulence. In this paper, using a power spectrum more general law instead standard value 11/3 amplitude factor constant 0.033, temporal spectra presentative phase effects, irradiance angle arrival...

We investigate the performance of a dual-hop mixed radio frequency (RF)/free space optical (FSO) system with variable-gain relaying. The RF link is modeled by <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\kappa$</tex-math></inline-formula> - notation="LaTeX">$\mu$</tex-math></inline-formula> shadowed distribution, which unifies popular channel models. FSO subject to atmospheric turbulence non-zero...

Instead of Zernike polynomials, ellipse Gaussian model is proposed to represent localized wave-front deformation in researching pointing and tracking errors inter-satellite laser communication links, which can simplify the calculation. It shown that both depend on center deepness h, radiuses a b, distance d distortion change regularly as they increase. The maximum peak values always appear around h=0.2lambda. influence up 0.7microrad for error, 0.5microrad error. To reduce impact errors,...