High efficiency wireless optical links in high transmission speed wireless optical communication networks

Author(s):  
Ahmed Nabih Zaki Rashed
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Nidhi Patle ◽  
Arockia Bazil Raj ◽  
Chinchu Joseph ◽  
Nishant Sharma

Abstract In the present era of technology, it is quite fascinating to design a system capable of transmitting information from one end to another by using the optical spectrum. This system differs from optical fibre communication in terms of channel medium. Optical fibre technology uses the end-to-end physical connection via fibre. In contrast, Light-based wireless communication networks, also known as wireless optical communication (WOC) networks or fibreless optical communication networks, use light as a carrier and air as an unguided propagation media for transmission. Fibreless optical communication eliminates the need for Licensing and Buried Fibre Cables; also, its installation is relatively easy. This survey article describes the evolution of WOC technologies right from the old methods of communication to today’s deep-space optical satellite communication. This article briefly describes the WOC system working principle, categorization of wireless optical systems (based on the carrier frequency wavelength, distance covered, and application), different modulation techniques adopted for wireless optical communication, challenges associated with channel medium and channel modelling, performance analysis of WOC system, various application areas of WOC network, commercial developments in the field of WOC, and some other emerging trends associated with WOC.


2019 ◽  
Vol 28 (1) ◽  
pp. 224-231
Author(s):  
Randa S. Hammad ◽  
El_Sayed M. El_Rabaie ◽  
Fathi. E. Abd-El-Samie ◽  
Ibrahim M. El-Dokany

2021 ◽  
Vol 17 (2) ◽  
pp. 155014772199961
Author(s):  
Zhongwei Shen ◽  
Hongxi Yin ◽  
Yanjun Liang ◽  
Rigele Maao ◽  
Lianyou Jing

A routing-benefited deployment algorithm combining static and dynamic layouts is proposed, and its comprehensive performance evaluation is given in this article. The proposed routing-benefited deployment algorithm is intended to provide a suitable network deployment and subsequent data transmission approach for underwater optical networking and communication. Static nodes are anchored for long-term monitoring, and movable nodes can adjust their depths based on the virtual force and move with the variation of area-of-interest changing. Then, nodes begin to collect data that they can monitor and transmit to sink nodes. Here, the underwater wireless optical communication model is described to actualize the real environment, and the vector-based forwarding protocol is particularly considered to compare the impact of different deployment algorithms on routing. It is shown by simulation experiment results that routing-benefited deployment algorithm outperforms several existing traditional virtual force deployment algorithms in terms of coverage, lifetime, energy consumption balance, packet-loss rate, and time-delay.


Sensors ◽  
2020 ◽  
Vol 20 (23) ◽  
pp. 6789
Author(s):  
Katarzyna A. Rutkowska ◽  
Anna Kozanecka-Szmigiel

Tunable diffraction gratings and phase filters are important functional devices in optical communication and sensing systems. Polarization gratings, in particular, capable of redirecting an incident light beam completely into the first diffraction orders may be successfully fabricated in liquid crystalline cells assembled from substrates coated with uniform transparent electrodes and orienting layers that force a specific molecular distribution. In this work, the diffraction properties of liquid crystal (LC) cells characterized by a continually rotating cycloidal director pattern at the cell substrates and in the bulk, are studied theoretically by solving a relevant set of the Euler-Lagrange equations. The electric tunability of the gratings is analyzed by estimating the changes in liquid crystalline molecular distribution and thus in effective birefringence, as a function of external voltage. To the best of our knowledge, such detailed numerical calculations have not been presented so far for liquid crystal polarization gratings showing a cycloidal director pattern. Our theoretical predictions may be easily achieved in experimental conditions when exploiting, for example, photo-orienting material, to induce a permanent LC alignment with high spatial resolution. The proposed design may be for example, used as a tunable passband filter with adjustable bandwidths, thus allowing for potential applications in optical spectroscopy, optical communication networks, remote sensing and beyond.


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