This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see https://creativecommons.org/licenses/by/4.0/ This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/JPHOT.2020.3034177, IEEE Photonics Journal IEEE Photonics Journal xxxxx K-Band Centralized Cost-Effective All-Optical Sensing Signal Distribution Network M. A. Esmail 1,6 , A. Ragheb 2 , H. Seleem 3 , H. Fathallah 4 , Senior Member, IEEE, and S. Alshebeili 2,5 1 Communications and Networks Enginnering Department, Prince Sultan University, Riyadh 11586, Saudi Arabia, 2 KACST-TIC in Radio Frequency and Photonics Center (RFTONICS), Riyadh 11421, Saudi Arabia, 3 Department of Electrical Communications and Electronics, Tanta University, Tanta 31527, Egypt, 4 Computer Department of the College of Science of Bizerte, University of Carthage, Tunis, Tunisia, 5 Electrical Engineering Department, King Saud University, Riyadh 11421, Saudi Arabia, 6 Smart Systems Engineering Laboratory, College of Engineering, Prince Sultan University, Riyadh 11586, Saud Arabia, DOI: 10.1109/JPHOTxxx.XXXXXXX 1943-0655/$25.00 c xxx IEEE Manuscript received xxxxxx x, xxxx; revised xxxxxx xx, xxxx. First published xxxxxx xx, xxxx. Current version published xxxxxx xx, xxxx. This Project was funded by the National Plan for Science, Technology and Innovation (MAARIFAH), King Abdulaziz City for Science and Technology, Kingdom of Saudi Arabia, Award Number (3-17-09- 001-0012). Abstract: In this work, we propose and experimentally demonstrate a centralized all-optical network for sensing signal distribution to a large number of remote sites. The reach range of high-resolution sensing systems is often limited due to atmospheric effects. Employing a centralized optical fiber network for signal distribution to different nodes increases the effective reach distance, decreases the power consumption, and reduces the overall cost of the sensing system. The proposed centralized all-optical network is structured such that it has an all-optical wavelength converter hosted at a central office to guide a sensing signal to a specific site/sensor. This system enables using shared equipment in the transmitter which in turn reduces the overall cost of the network. The performance of the proposed system is investigated by transmitting a radar signal over various transmission media, i.e. fiber, free space optic (FSO), and hybrid fiber/FSO. Some empirical formulas for the signal power and dynamic range (DR) are derived. The results show that although optical signal switching introduces a penalty of 2.5-dB in the signal (DR), the signal still preserves its good shape and spectrum quality. In addition, the experimental results show the system performance with respect to target detection and range estimation. Index Terms: All-optical network, free-space optics, sensing signal distribution, semiconductor optical amplifier (SOA), wavelength conversion. 1. Introduction A SENSOR network is a network that combines arrays of sensor elements which are deployed to perform different tasks such as safety, security, environmental monitoring, etc. Among these sensor networks is radar sensor network which is used for various applications in many fields. In the past, the development of radar was dedicated to military and security applications, such as air defense, weapon guidance, ship surveillance, and so forth. However, currently, radar sensors are being used for several civilian applications, such as objects detection and positioning, Vol. xx, No. xx, June 2020 Page 1