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An 82-m 9 Gb/s PAM4 FSO-POF-UWOC Convergent System
摘要： With the increasing demands in free-space/underwater environmental monitoring, disaster precaution, and manufacturing industry applications, free-space optical (FSO)-plastic optical fiber (POF)-underwater wireless optical communication (UWOC) convergence is designed to be a promising framework for providing long-haul free-space with underwater links. An 82-m 9 Gb/s four-level pulse amplitude modulation (PAM4) system employing a 405-nm blue-light injection-locked laser diode (LD) is thereby offered and practically demonstrated. Results reveal that a 1.8-GHz 405-nm blue-light injection-locked LD can be effectively applied for a 9 Gb/s PAM4 signal transmission over 50 m FSO link, 30 m graded-index (GI)-POF transportation, and 2 m clear ocean underwater channel. To the authors’ understanding, this study is the first to practically build an 82-m 9 Gb/s PAM4 FSO-POF-UWOC convergent system that effectively constructs a long-haul optical wireless-wired-wireless link using doublet lenses, GI-POF, and optical beam reducer. The performances of the proposed convergent systems are analyzed by bit error rate and non-return-to-zero eye diagram in real-time over an 82-m transport. This framework is the leading one to establish a long-haul FSO-POF-UWOC convergent system with qualified transmission performances. It guides a promising way to facilitate wide applications in the convergence of FSO, POF and UWOC.
关键词： Graded-index plastic optical fiber,Underwater wireless optical communication,Four-level pulse amplitude modulation,Free-space optical
更新于2025-09-23 15:23:52
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Aberrated Microlenses to Reduce Crosstalk in Free Space Optical Interconnects Systems
摘要： A free space optical interconnects system that uses Gaussian beams and focusing microlenses with spherical aberration has been considered. Numerical results show that the use of microlenses with negative spherical improves the signal-to-crosstalk ratio of the interconnects system at some optimum positions of the detector array. An expression for output field at the detectors plane is derived and used to evaluate the signal-to-crosstalk ratio.
关键词： lens spherical aberration,optical crosstalk,free space optical interconnects
更新于2025-09-23 15:23:52
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[IEEE 2018 International Conference on Current Trends towards Converging Technologies (ICCTCT) - Coimbatore, India (2018.3.1-2018.3.3)] 2018 International Conference on Current Trends towards Converging Technologies (ICCTCT) - Impact of Modulation Techniques for Hybrid-WDM Based FSO
摘要： Free space optical communication (FSO) provides high data rate by allowing light passed through the atmosphere. It is very effective and efficient technology for wireless communication. This emerging field basically uses invisible beams of light such as ultraviolet, infrared, etc. This work exclusively deals with the designing of hybrid WDM based FSO system using the simulation software Opti-System 7.0 with Minimum-Shift Keying and Differential-phase-shift keying. Further their study has been made as to which modulation techniques provides better means of communication. The normal rain weakening from rain power information which are gathered for a period for six months. The concert of the future system is evaluated in terms of Bit Error Rate, Q-factor, and Receiver Sensitivity are examined with respect to link distance for using rain attenuation 20.5dBm. The transmission wavelength and data rate is 1550nm and 2.5Gbps considered for investigation.
关键词： Receiver Sensitivity,Hybrid WDM,BER,Free space optical communication,DPSK,MSK
更新于2025-09-23 15:23:52
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An optical wireless communication system deploying active high-pass pre-emphasis circuit for high speed application
摘要： This article presents a high-speed optical wireless communication link with a newly proposed pre-emphasis circuit to increase transmission performance at higher data rates. The effectiveness of the pre-emphasis circuit has been verified through testing on an optical wireless link implemented with existing laser communications components in our laboratory operating at 1550 nm. When the proposed pre-emphasis circuit is included in the optical wireless link, we achieved bit-error-rate (BER) power penalty improvements of 1.6, 2.2, and 1.0 dB at 155 Mbps, 622 Mbps, and 1.244 Gbps, respectively at the BER of 2 × 10?3 compared with the optical wireless communication links without pre-emphasis circuit. For the lower BER of 10?9, BER power penalty improvements of 2.2, 3.7, 0.7 dB at 155 Mbps, 622 Mbps, and 1.244 Gbps are observed, which show the effectiveness of our proposed pre-emphasis circuit in optical wireless communications link.
关键词： pre-emphasis,optical communications,optical wireless communications,free space optical communications,optical wireless link
更新于2025-09-23 15:22:29
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[IEEE 2018 International Conference on Intelligent and Innovative Computing Applications (ICONIC) - Mon Tresor, Plaine Magnien, Mauritius (2018.12.6-2018.12.7)] 2018 International Conference on Intelligent and Innovative Computing Applications (ICONIC) - Atmospheric Effects on Free Space Optics Wireless Communication: Applications and Challenges
摘要： Demand for data and multi-media services in recent times has really grown and it is expected to grow more in the next decade with application ranges from high speed real-time/live streaming to live video-conferencing, and so the demand for new and richer data services to meet up with the new and more advanced applications. In other to meet up with these great users’ expectations, there is a need to explore other viable access network technologies that can offer services beyond what is already in the offering. Free space optical (FSO) communication system is the predominant choice to replace existing wireless technology with great availability of link capacity and huge bandwidth to meet the user’s expectation of the 21st century. This system is reliant on optics signal transmitted in a free space channel, hence termed FSO. This type of communication does not require any licenses for its operation and offers many features being the low-start up and operational cost, rapid development and high fiber-like bandwidth. FSO uses line-of-sight path for the communication between two points and beam of light to provide optical connection that can send and receive video, voice and data information. This technology provides a massive and unregulated bandwidth where a data rate in excess of 100Gbit/s is achievable over a distance of 1-4km. However, it suffers from degradation in the signal quality due to its susceptibility to atmospheric channel impairments which limits its wide deployment and quality of services. This paper explores the FSO system, atmospheric effects of implementing this system and mitigating techniques.
关键词： free space optical fiber-like,atmospheric channel,real-time,multi-media
更新于2025-09-23 15:22:29
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Physical Layer Security of Hybrid Satellite-FSO Cooperative Systems
摘要： In this paper, we study the physical layer secrecy performance of a hybrid satellite and free-space optical (FSO) cooperative system. The satellite links are assumed to follow the Shadowed-Rician fading distribution; and the channel of the terrestrial link between the relay and destination is assumed to experience the Gamma-Gamma fading. For the FSO communications, the effects of different types of detection techniques (i.e., heterodyne detection and intensity modulation with direct detection) as well as the pointing error are considered. We derive exact analytical expressions for the average secrecy capacity (ASC) and secrecy outage probability (SOP) for both cases of Amplify-and-Forward (AF) and Decode-and-Forward (DF) relaying. The asymptotic analysis for the SOP is also conducted to provide more insights on the impact of FSO and satellite channels on secrecy performance. It is found that with the AF with fixed gain scheme, the secrecy diversity order of the investigated system is only dependent on the channel characteristics of the FSO link and the FSO detection type, whereas the secrecy diversity is zero when the relay node employs DF or AF with variable-gain schemes.
关键词： land mobile satellite (LMS) channel,secrecy outage probability,hybrid satellite free-space optical (FSO) cooperative system,Physical layer security,average secrecy capacity
更新于2025-09-23 15:22:29
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Modeling of Short-Range Ultraviolet Communication Channel Based on Spherical Coordinate System
摘要： The study on short-range ultraviolet (UV) communication (UVC) channel modeling is often based on prolate-spheroidal coordinate system in previous studies. In this letter, we propose a single scattering coplanar model based on spherical coordinate system, where the transmitter beam and receiver field of view (FOV) can point arbitrarily under the limitation that the sum of transceiver elevation angles and half of their own FOV is less than 180°, and the transmitter beam and receiver FOV are above ground. We utilize the number of intersections between a special ray on the transmitter cone and the receiver conical surface to distinguish the UVC scenarios, which makes the analysis of UVC channel modeling comprehensible. Meanwhile, we validate the proposed model in comparison with the single scattering model and the Monte Carlo simulation model through numerical calculations. The results show that the proposed model agrees well with the both models. This work presents a new method to estimate the path loss of short-range UVC and provides guidelines for the experimental system design.
关键词： ultraviolet communications,Atmospheric propagation,free-space optical communication
更新于2025-09-23 15:22:29
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-Distribution Dual-Hop RF/FSO Systems
摘要： In this correspondence, we investigate the physical-layer security of a mixed radio frequency/free space optical (RF/FSO) dual-hop communication system for both fixed- and variable-gain relaying schemes. More specifically, we only assume that the eavesdropping happens at the RF link because the optical link has high security. We assume that all RF channels suffer from η–μ fading, while the FSO link experiences M-distributed fading. Then, we derive some analytical results for the average secrecy rate and the secrecy outage probability.
关键词： secrecy outage probability,Average secrecy rate,radio frequency-free space optical,M-distributed fading,η-μ fading,physical-layer security
更新于2025-09-23 15:22:29
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Error rate and ergodic capacity of RF-FSO system with partial relay selection in the presence of pointing errors
摘要： This paper presents an analysis of a multiple dual-hop relaying system, which is composed of km-class radio frequency (RF)-free-space optical (FSO) links. Partial relay selection based on outdated channel state information (CSI) is employed in order to select active relay for further transmission. Amplify-and-forward relaying protocol is utilized. The RF links are assumed to be subject to Rayleigh fading, and the FSO links are influenced by both Gamma-Gamma atmospheric turbulence and pointing errors. On the basis of our previously derived expression for cumulative distribution function of the equivalent signal-to-noise ratio of the whole system, we derive novel analytical expressions for the average bit-error rate (BER) and ergodic capacity that are presented in terms of the Meijer’s G-function and extended generalized bivariate Meijer’s G-function, respectively. The numerical results are confirmed by Monte Carlo simulations. Considering the effect of time-correlation between outdated CSI and actual CSI related to the RF channel at the time of transmission, the average BER and the ergodic capacity dependence on various system and channel parameters are observed and discussed. The results illustrate that the temporal correlation between outdated and actual CSI has strong effect on system performance, particularly on BER values, when FSO hop is influenced by favorable conditions.
关键词： ergodic capacity,free-space optical systems,Bit error rate,partial relay selection,radio frequency systems.
更新于2025-09-23 15:22:29
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Bidirectional SMF and PF-POF transmission of 400 Gbps Nyquist shaped on DP-QPSK systems
摘要： This work experimentally shows a transmission path based on standard single-mode optical fiber and perfluorinated graded-index plastic optical fiber with the connections between distinct optical fibers being made by fiber collimators using free-space optical transmission. The data stream consists of a bidirectional 400 Gbps optical transmission using four wavelength channels with quadrature phase-shift keying modulation format, combined with dual-polarization and Nyquist pulse-shaped. The results obtained seeks to study the use of short-distance cables in plastic optical fiber as a flexible means of interconnection, when inserted between single-mode optical fibers or as a coupling medium between devices with single-mode optical inputs/outputs located in data centers/video headends.
关键词： bidirectional transmission,optical network convergence,free-space optical connection,Perfluorinated polymer optical fibers
更新于2025-09-23 15:21:21