Design and Analysis of Commercially Viable Free-Space Optical Communication Link for Diverse Beam Divergence Profiles

With an exponential increase in the use of smart devices and with increasing demand for high-speed data applications, the Radio Frequency and Microwave links will find themselves almost incapable of meeting this deficit. Free-space optical (FSO) links are poised to take the leading role as communication systems for futuristic needs in providing cost-effective and high-speed connectivity to end-users. However, on the flip side, the reliability of FSO links has an intrinsic relationship with the characteristics of the atmospheric channel. During the propagation, the atmospheric adversities result in the geometrical spreading of the FSO beam which in turn has consequential degrading effects on the link performance. In this work, an FSO communication system based on practical, commercial, and realistic parameters has been proposed with the intent of accurately determining the co-relation between different beam divergence profiles and overall link performance. For different beam divergence profiles, the proposed link has been evaluated for reference bit error rate (BER) of 10–9 which is an ideal condition for delivering high-speed data access to the end-users. During the analysis, the practical constraints related to the trade-off between the maximum possible link range and beam divergence have also been optimized. The findings of this work will be crucial for engineers and designers in configuring FSO links for improved link range and reliability.

Tracing Evolution of Angle-Wavelength Spectrum along the 40-m Postfilament in Corridor Air

Postfilamentation channel resulting from filamentation of freely propagating 744-nm, 5-mJ, 110-fs pulse in the corridor air is examined experimentally and in simulations. The longitudinal extension of postfilament was determined to be 55–95 m from the compressor output. Using single-shot angle-wavelength spectra measurements, we observed a series of red-shifted maxima in the spectrum, localized on the beam axis with the divergence below 0.5 mrad. In the range 55–70 m, the number of maxima and their red-shift increase with the distance reaching 1 μm, while the pulse duration measured by the autocorrelation technique is approximately constant. Further on, for distances larger than 70 m and up to 95 m, the propagation is characterized by the suppressed beam divergence and unchanged pulse spectrum. The pulse duration increases due to the normal air dispersion.

Performance analysis of beam divergence propagation through rainwater and snow pack in free space optical communication

In the present work the future communication requirements need to fulfill with high data rate, FSO (free space optic) with it is tremendous potential is the solution. This research observed the effectiveness analysis of FSO systems by modifying one of the most important FSO parameters beam divergence, under the most affected weather attenuating condition Rainwater and snow pack. The simulation is obtained and analyzed under single channels CSRZ-FSO (carrier-suppressed return-to-zero/free space optical) systems having capacity of 40 Gbps between two transceivers with variable distance. The connection is presently under 5 meteorological turbulences (light rain, medium rain, wet snow, heavy rain and dry snow). The results show the heavy rain and dry snow have a very high attenuation carried out in terms of Q-factor. this result led us to conclude that small divergence offers significant performance improvement for FSO link and this performance decrease every time the beam divergence increase, Therefore, to build inexpensive and reliable transmission media, we go with new method that still in the experiment area called hybrid RF/FSO (radio frequency/free space optical) that compatible with atmospherically status.

OPTIMIZATION OF DISTRIBUTED STRUCTURES OF ATMOSPHERIC OPTICAL COMMUNICATION NETWORK

Рассмотрены проблемы оптимизации распределенной структуры атмосферной лазерной коммуникационной сети. Поставлена и решена задача оптимизации распределенной атмосферной оптической коммуникационной сети, содержащей один передающий и n приемных узлов. Определено выражение оптимальной связи между дивергенцией луча на входах приемных узлов и расстоянием между передатчиком и этими узлами, при реализации которой суммарное затухание в системе при условии неизменности других факторов, способствующих ослаблению сигнала, достигает минимума. The problems of optimization of the distributed structure of atmospheric laser communication network are considered. The problem of optimization of distributed atmospheric optical communication network containing one transmitting and n receiving nodes is formulated and solved. The formula determining the relation between beam divergence at the input of receiving points and the distance between these points and transmitter is obtained. Technical implementation of this formula brings to a minimum of total attenuation in the system, provided that other factors potentially causing signal attenuation are unchanged.