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This paper compares and discusses two different types of Wavelength Division Multiplexing (WDM) Passive Optical Network (PON) configuration. First is with Semiconductor Optical Amplifier (SOA-WDMPON) and second is with Erbium Doped Fiber Amplifier (EDFA-WDM-PON). The performance of the system is measured by calculating Bit Error Rate (BER) for various values of bitrate and length of fiber. The novelty of the paper is that the results are obtained for higher bitrate up to 30 Gbps and higher fiber lengths up to 80 Km. Compared to previously published results this paper tries to achieve good BER and Q-factor. WDM-PON with four channels is designed, incorporating SOA and EDFA amplifiers to achieve optimized gain and noise performance. Unlike previous studies, this paper integrates recent innovations, such as quantum dot SOA and tunable EDFA, into a practical design that addresses critical challenges in high-speed optical networks, including scalability, signal integrity, and costeffectiveness. The importance of this paper is reflected in its comprehensive overview of stateof-the-art developments and its applicationoriented approach, offering valuable insights for optimizing optical amplification technologies for modern and future communication networks. [ABSTRACT FROM AUTHOR]

With the development of the Internet of Things, cloud networking, and 4K/8K high-definition video, global internet traffic has seen a dramatic increase. This surge in traffic has placed higher demands on the performance of optical networks, featuring higher data rates, lower latency, and lower cost. The passive optical network (PON) is a representative scenario of optical access networks. Issues such as burst-mode detection in upstream PON scenarios, flexible rate allocation in downstream scenarios, and the simplification of hardware complexity at the optical network unit (ONU) side have attracted considerable attention. Compared to intensity modulation/direct detection (IM/DD), a recently proposed coherent PON incorporates a local oscillator laser at the receiver, enabling superior receiver sensitivity, spectrally efficient modulation, linear optical field recovery, and flexible channel selection. These features significantly enhance the flexibility and data rates of PON systems. This paper provides a comprehensive review of the development of coherent PONs, particularly in aspects of preamble design for burst-mode detection in upstream scenarios, the design of flexible rate PONs in downstream scenarios, and solutions for reducing hardware complexity at the ONU side. [ABSTRACT FROM AUTHOR]

A high‐capacity lithium‐niobate‐on‐insulator (LNOI) optical transmitter for next‐generation passive optical‐networks (PONs) is proposed and demonstrated with ultra‐low temperature‐dependence for the first time by simultaneously introducing Z‐ and Y‐propagation LNOI photonic waveguides. There are five wavelength‐division‐multiplexed channels involved with the center wavelengths of 1270/1300/1342/1537/1577 nm, and the photonic filters are realized by integrating amplitude‐apodized multimode waveguide gratings (MWGs) and mode (de)multiplexers designed with Z‐propagation LNOI photonic waveguides, which are found to be with a low thermo‐optic coefficient and thus enable the athermalization. Meanwhile, high‐speed optical modulators connected at the add ports of the photonic filters for the 1342/1577 nm channels are developed with Y‐propagation LNOI photonic waveguides with the maximal electro‐optic effect. For the fabricated on‐chip optical transmitter, box‐like spectral responses are achieved with ultra‐low excess losses of <0.5 dB and low inter‐channel crosstalk of < −26 dB for all the channels whose bandwidths are respectively ∼16/20/4/15/5 nm as expected. The present LNOI photonic chip is nearly athermal, exhibiting very low temperature‐dependence less than 8.7 pm/°C in the full wavelength range of >300 nm. Finally, high‐capacity data transmissions of 50/100 Gbps on‐off‐keying signals and 100/200 Gbps four‐level‐pulse‐amplitude‐modulated signals are demonstrated, providing a promising solution for next‐generation PONs. [ABSTRACT FROM AUTHOR]

In recent times, there has been enormous growth in internet-based applications such as online entertainment platforms, video conferencing and voice over internet protocol (VoIP) applications which might be the trend in future. In order to support such bandwidth-hungry applications, the speed of the network should be enhanced. Increasing the infrastructure of the network requires heavy investment. Another alternative to increase the capacity of the network is to use dense wavelength division multiplexing (DWDM) which also results in increased costs as the lasers and other equipment needed for generation of wavelengths are required. In this work, an alternative cost effective technique is used to create a DWDM scenario using optical flat comb source (OFCS) by combining amplitude modulator (AM) and single drive mach zehnder modulator (SD-MZM). The spectral lines generated using this procedure can be used in Passive Optical Network (PON) as input sources. In this paper, 51 flat spectral lines are generated and transported over a distance of 100 km which are also capable of supporting a data rate of greater than 10 Gbps in a single spectral line. [ABSTRACT FROM AUTHOR]

Wavelength division multiplexing (WDM) is one of the emerging technologies for data transmission in 5G access network assembly between the antenna unit (AU) and the distribution unit (DU). Here, in this work, we evaluate and analyze a dense wavelength division multiplexing (DWDM) — passive optical networks (PONs) employing erbium–ytterbium-doped fiber amplifier (EYDFA) + Raman hybrid optical amplifier (HOA) using two modulation schemes — modified duobinary return to zero (MDRZ) and differential phase shift keying (DPSK) for alternate channels, where the channel count has been varied from 8 to 40. The system has been analyzed over the wavelength span of 1550–1558.8 nm with a channel spacing, input power and data rate of 25 GHz, 0 dB and 40 Gb/s, respectively. An average gain, gain ripple and optical signal-to-noise ratio (OSNR) of 20.87, 0.95 and 30 dB, respectively have been observed in the case of HOA along with the achievement of Q-factor of up to 9 at the receiving end of the system. The DPSK-modulated channels result in higher values of gain and OSNR along with lower gain ripple as compared to MDRZ channels making the proposed system a good option for 5G access network applications. [ABSTRACT FROM AUTHOR]

High-capacity communication networks are built to provide high throughput and low latency to accommodate the growing demand for bandwidth. However, the provision of these features is subject to a robust underlying network, which can provide high capacity with maximum reliability in terms of the system's connection availability. This work optimizes an existing 2D spectral–spatial optical code division multiple access (OCDMA) passive optical network (PON) to maximize connection availability while maintaining desirable communication capacity and capital expenditure. Optimization is performed by employing ring topology at the feeder level, which is used to provide a redundant path in case of connection failures. Furthermore, high transmission capacity is ensured by utilizing a pseudo-3D double-weight zero cross-correlation (DW-ZCC) code. The analysis is performed with Optisystem simulations to observe the performance of the system in terms of bit error rate (BER), received power, and eye openings. It is observed that the introduction of ring topology at the feeder level of the PON does not impact the overall transmission capacity of the system. The system can still support maximum transmission capacity at receiver sensitivities of up to −19 dB. Reliability analysis also shows that the optimized ring-based architecture can provide desirable connection availability compared to the existing system. [ABSTRACT FROM AUTHOR]

Driven by a large number of emerging diversified services, in the 5G and beyond era, concurrent direct inter-ONU and upstream communications inside a PON-based mobile access network are highly desirable to provide dynamic, ultra-dense, and fast ONU-to-ONU (without involving an OLT) and ONU-to-OLT connections. To cost-effectively deliver highly dynamic and low latency direct inter-ONU communications, this paper proposes and experimentally demonstrates novel concurrent direct inter-ONU and upstream communications in an upstream 27 km, >62.47 Gbit/s IMDD PON. For supporting inter-ONU communications between a large number of ONUs, an advanced passive remote node is also proposed. Based on different passive optical components, this remote node can be implemented using two approaches, which can, respectively, reduce the inter-ONU signal power losses by >12.2 dB and >16.6 dB (for 128 ONUs) in comparison with existing inter-ONU communication techniques' remote nodes. In each ONU and OLT, a single pair of cascaded IFFT/FFT-based point-to-multipoint (P2MP) flexible optical transceivers are employed to simultaneously and dynamically establish multiple ONU-to-ONU and ONU-to-OLT communications according to actual users' requirements. Experimental results show that the proposed network has excellent robustness against various transmission system impairments, including chromatic dispersion, the Rayleigh and Brillouin backscattering effects, and the channel interference effects. For each ONU, dynamic channel allocation can be made without compromising its overall performance. [ABSTRACT FROM AUTHOR]

This work proposes a new hybrid bidirectional standard single mode fiber (SSMF)/free space optical (FSO) dual polarization quadrature amplitude modulation (DP‐QAM) employing optical orthogonal frequency division multiplexing (OFDM). An optical multicarrier generator (OMG) source is utilized. The suggested model is simulated using VPI photonics software. Thirty‐two optical OFDM channels are used; each carrier's 30 Gbps information data with DP‐QAM are employed to improve the performance of the fifth‐generation passive optical network (5G‐PON) for downstream and upstream transmission. In addition, 16‐QAM signals are used in DP. The impact of continuous wavelength (CW) lasers and high data rates in the proposed 5G‐PON has been investigated for DP‐QAM‐OFDM. The results reveal 0.96 Tb/s and 0.1 Tb/s for the downstream and upstream directions, respectively, under different turbulence effects. Furthermore, the simulation results show that the proposed model can achieve an SSMF length and FSO propagation ranges of 20 km and 2 km, respectively, with the symbol error rate (SER) (<10−9) and error vector magnitude (EVM) (<0.186). [ABSTRACT FROM AUTHOR]

Computational imaging, as a novel technology utilizing encoded image acquisition, relies on intelligent decoding methods for effective image restoration and sensing. Optical computing‐based decoders can efficiently process and extract features from pre‐sensor information, reducing the computational burden on digital computers. However, mainstream parallel optical neural network (ONN) architectures based on wavefront propagation typically possess complex network structures and high‐precision parameters, which pose challenges in terms of precise fabrication and system calibration, as well as sensitivity to signal‐to‐noise ratios. In this work, a binary‐weighted optical computing engine is proposed with spatial multiplexing and aggregation (B‐OSMA), a large‐scale passive ONN implementation that achieves high‐efficiency image sensing. Employing B‐OSMA as an optical decoder, demonstrated image categorizing from 2% compressive is experimented sampling with 92.0% and 83.8% accuracy on MNIST and fashion‐MNIST datasets, respectively, approaching the performance of full‐precision electronic computing while reducing storage requirements by 97%. Compared to conventional ONNs with analog weights, the B‐OSMA exhibits enhanced resilience against systematic errors and ambient noise. This work represents a significant advancement towards practical applications of optical computing in image sensing. [ABSTRACT FROM AUTHOR]

Today, in passive optical networks (PON) the major issue is call blocking and it is getting worse as there is an increase in the number of connection requests but the wavelength channels in fiber links are limited. In this research, greedy-based priority routing and wavelength assignment traffic grooming (GPRWATG) technique is proposed aimed at reducing call blockage. In this scheme, to avoid optical–electrical–optical correspondence, firstly the grooming of connection requests with same source destination (s–d) is performed. According to the priority of these groomed connection requests, wavelength assignment and routing is assigned. This approach not only addresses the call blocking issue but also aligns with industry demands for improved network infrastructure. The proposed work performance is analyzed for blocking probability (BP), congestion, and its performance is compared with the non-priority-based routing and wavelength assignment traffic grooming (NPRWATG) and priority-based routing and wavelength assignment traffic grooming (PRWATG) schemes. The proposed method has 23.6 % lower congestion as compared to PRWATG and 21 % lower congestion as compared to NPRWATG. Also, the BP of GPRWATG is 26 % less than PRWATG and 21 % less than NPRWATG. Thus, it can be analyzed that by using the proposed technique, the BP as well as the congestion of the network altogether is reduced in comparison to the existing state-of-art techniques. [ABSTRACT FROM AUTHOR]

In this article, the comb wavelength division multiplexing passive optical network (Comb WDM-PON) system has been simulated. Simulation models were created in VPI photonics. The proposed system employs 140 Gbps for seven comb lines. Analytical modelling and simulations are performed for a flat comb source with seven comb lines, variable channel spacing, and a center wavelength. As a result, the performance of the comb WDM-PON system that utilizes a single differential Mach–Zehnder (DiffMZ) modulator comb source is also investigated using different comb line numbers. The total capacity of the system increases as the number of comb lines increases. However, the system performance is degraded. Data rates of 80 Gbit/s can be achieved at the threshold bit error rate of BER (1 × 10−9), over a transmission distance of 200 km using 4 comb lines with a multi-diagonal (MD) code for 4 OLTs. [ABSTRACT FROM AUTHOR]

This paper is successfully demonstrated simulative comparison and investigation of 32 channels with 0.8 nm frequency spacing bidirectional wavelength division multiplexing passive optical network (WDM-PON) having 640 and 320 GB/s data rate in downstream and upstream transmission by using CRZ-DPSK/NRZ modulation formats respectively. The maximum reach of the system has been configured to 100 km by employing different post-dispersion compensation techniques such as EDC, DCF, OPC, and FBG in uplink and downlink transmission for compensate the effect of chromatic dispersion in propagating channel. An EDFA optical amplifier is placed after DCF for boosting the amplitude of weak signals downstream. Apart from this, the RSOA amplifier is installed at the ONT end for reflecting and re-modulates the same wavelengths to the CO terminal without using any external optical light source. The performance comparison of distinct compensation schemes are evaluated in terms of BER, Q factor, and Eye diagrams. It has been observed that the FBG and DCF are more robust compensation techniques as compared to EDC and OPC in the bidirectional WDM-PON. The maximum satisfying value of BER has been observed in downlink and uplink transmissions are 10−26 and 10−13 for FBG and DCF respectively. [ABSTRACT FROM AUTHOR]

Code division multiple access in optical domain has a potential in next-generation long-haul transmission systems. However, multiple user interference is a snag in functioning of system employing OCDMA. A detailed analysis of multiple access interference (MAI) which causes a severe degradation in the system performance is done in this paper. An optimum MAI cancellation scheme has been proposed. This cancellation scheme depends not only on using the excellent correlation property of the double padded modified prime codes (DPMPC) as spreading sequence but also on employing minimum shift keying (MSK). The performance of the proposed cancellation scheme is compared with the existing techniques of FSK-OCDMA and PPM-OCDMA cancellation techniques. MSK-OCDMA cancellation technique achieves the lowest bit error rate of 10−20. It is also efficient in power. It achieves lowest bit error rate at same number of mean photon number when compared to the existing techniques. The investigations reveal that MSK-OCDMA cancellation technique outperforms FSK-OCDMA and PPM-OCDMA cancellation schemes. [ABSTRACT FROM AUTHOR]

Passive optical network (PON) was designed in this paper. The design aim was to locate faulty line of service professionally without extra effort. In the literature, there were various PON-design methodologies. However, a design with fewer components and less faulty line tracking was a challenge. The suggested approach tried to overcome the leakage in the state-of-the-art, such that, the PON network would be able to serve forty-eight optical network units (ONUs). At the same time, the design has to have the capability to distinguish the dropped line of service straightforwardly. The design in this thesis mainly depends on the fiber Bragg gratings (FBGs) to create six-groups, in each group, there are eight-branches. Each branch serves as an end-user/customer point. The capacity of fault location was achieved for ONUs distanced/located as far as 20 Km from the central office (CO). There was only one optical spectrum analyser (OSA) inside the CO. This OSA employed to monitor the whole network groups, i.e., forty-eight branches/ONU were screened inside the CO to predict the fault location. The system is built using the OptiSystem software package version 14. [ABSTRACT FROM AUTHOR]

This work addresses the optimized planning of survivable optical 5G Xhaul access networks employing passive Wavelength Division Multiplexing (WDM) technologies. Specifically, it focuses on the reliability of optical transmission paths connecting remote radio sites to a central hub ensured by using a novel, cost-effective, flexible, and dedicated path protection (DPP-F) scheme, protecting against single-link failures. The proposed DPP-F network protection approach allows for switching of individual wavelengths or the complete multiplexed WDM signal, flexibly applying the best switching option according to given traffic demands. Concurrently, it enables traffic aggregation on the transmission paths from the end and intermediate nodes to minimize the overall network deployment cost. The problem of selecting primary (working) and backup (protection) paths, together with the selection of the best switching and traffic aggregation options, is modeled and solved as a mixed-integer linear programming (MILP) optimization problem. To evaluate the cost savings achieved with DPP-F, we compare it with two reference DPP schemes based on switching the entire multiplexed WDM signal (DPP-M) and individual wavelengths (DPP-W). Numerical experiments conducted across a wide range of network scenarios reveal, among other things, that DPP-F's performance is at least as good as that of the reference methods, bringing significant cost savings (from several to tens of percent) in most of the analyzed network scenarios. [ABSTRACT FROM AUTHOR]

To guarantee the reliability of Tactile Internet (TI) applications such as telesurgery, which demand extremely high reliability and are experiencing rapid expansion, we propose a novel smart resilience mechanism for Next-Generation Ethernet Passive Optical Networks (NG-EPONs). Our architecture integrates Artificial Intelligence (AI) and Software-Defined Networking (SDN)-Enabled Broadband Access (SEBA) platform to proactively enhance network reliability and performance. By harnessing the AI's capabilities, our system automatically detects and localizes fiber faults, establishing backup communication links using Radio Frequency over Glass (RFoG) to prevent service disruptions. This empowers NG-EPONs to maintain uninterrupted, high-quality network service even in the face of unexpected failures, meeting the stringent Quality-of-Service (QoS) requirements of critical TI applications. Our AI model, rigorously validated through 5-fold cross-validation, boasts an average accuracy of 81.49%, with a precision of 84.33%, recall of 78.18%, and F1-score of 81.00%, demonstrating its robust performance in fault detection and prediction. The AI model triggers immediate corrective actions through the SDN controller. Simulation results confirm the efficacy of our proposed mechanism in terms of delay, system throughputs and packet drop rate, and bandwidth waste, ultimately ensuring the delivery of high-quality network services. [ABSTRACT FROM AUTHOR]

Passive Optical Networks (PONs) are telecommunication technologies that use fiber-optic cables to deliver high-speed internet and other communication services to end users. PONs split optical signals from a single fiber into multiple fibers, serving multiple homes or businesses without requiring active electronic components. PONs planning involves designing and optimizing the infrastructure for delivering fiber-optic communications to end users. The main contribution of this paper is the introduction of tailored operators within a genetic algorithm (GA) optimization approach for PONs planning. A three vector and an aggregator vector are devised to account, respectively, for physical and logical connections of the network, facilitating the execution of GA operators. This codification and these operators are versatile and can be applied to any population-based algorithm, not limited to GAs alone. Furthermore, the proposed operators are specifically designed to exploit the unique characteristics of PONs, thereby minimizing the occurrence of unfeasible solutions and accelerating convergence towards an optimal network design. By incorporating these specialized operators, this research aims to enhance the efficiency of PONs planning, ultimately leading to reduced costs and improved network performance. [ABSTRACT FROM AUTHOR]

Optical communications and their security have been got a great attention. In this work, a simple, low cost and secure optical system integrating orthogonal frequency division multiplexing-based passive optical network (OFDM-PON) and chaotic theory is proposed. In the proposed system, a novel scheme of quadrature amplitude modulation (QAM) encryption method is adopted. For privacy of image and video encryption, the process of encryption consists of two processes and a 3D chaotic system is employed. The chaotic system is used to generate the encryption sequences. In the first stage, the first generated chaotic sequence is XORed with the incoming data. While in the second stage, the QAM symbol is remapped using the other two generated chaotic sequences. Generally, the proposed system is designed to provide secure data, videos, and images transmission. The proposed system is simulated and evaluated with a transmission of a 10 Gb/s along 50 km single-mode fiber (SMF). The performance of the proposed system showed that there is a performance enhancement in terms of Peak to average power ratio (PAPR) and bit error rate (BER). The BER of unauthorized user is around 0.6147, while the PAPR is reduced to approximately half. The proposed system is simple and doesn't require complex computations. It requires simple analog multiplexers for its implementation. [ABSTRACT FROM AUTHOR]

In this paper, the system consists of 80 Gbps next-generation passive optical network stage 2 (NG-PON2) co-existing with gigabit passive optical network (GPON) and 10 Gbps gigabit passive optical network (XG-PON) has been presented. The performance of the system has been evaluated for minimum bit error rate (BER) for varied distances (40 km to 100 km). It has been observed that due to the inadequate performance of XG-PON for upstream for higher lengths; the proposed system is limited to 40 km fiber length. To overcome this problem the proposed system is further simulated by increasing upstream transmission power of GPON and XG-PON. With the optimum parameters, the system maximum distance of 60 km has been reached for all GPON, XG-PON, and NG-PON2 without any inline amplification. [ABSTRACT FROM AUTHOR]

Summary Even with existing methodologies, dynamic resource allocation, service inconsistency, operational costs, and excess energy/power consumption in optical access networks remain the key challenges for the next‐generation passive optical network (NG‐PON) design and development. This paper introduces a novel method for analyzing energy/power consumption in time and wavelength division multiplexed (TWDM) passive optical networks (PONs) with a ring‐based topology. We propose subscriber‐based channel allocation models (CAMs) for on‐demand services, allocate bandwidth dynamically, and evaluate their downstream power consumption. To determine the necessary optical devices for the various CAMs, we investigate subscriber take‐up rates by optimizing the utilization of optical components based on active subscribers. Implementing a novel Poisson distribution‐based network traffic model addresses energy‐related concerns and explores optimization techniques to minimize power and improve energy efficiency. With a take‐up rate of 64 active subscribers, simulation results show significant power consumption reductions ranging from 62.2 to 67.7%, achieved by the proposed subscriber‐based architecture models with varying subscriber counts, when compared with the conventional model. The model with the most subscribers (2048 subscribers) saves the most energy by reducing power consumption to 292 W from the conventional model's (2048 subscribers) 440 W. Furthermore, the model with the most subscribers saves 33.4% of energy, outperforming other subscriber‐based architecture models without affecting QoS even during peak hours of the day. These numerical results show that TWDM‐PONs with the most subscribers exhibit improved energy efficiency than the conventional and other proposed subscriber‐based architecture models. [ABSTRACT FROM AUTHOR]

Recently, dense wavelength division multiplexing passive optical networks (DWDM-PONs) have become a considerable choice for 5G and beyond fronthaul implementations. Formerly, we have proposed a full-duplex bidirectional DWDM-PON architecture convenient for those implementations and analyzed the combined dual impact of four-wave mixing (FWM) and stimulated Raman scattering (SRS) nonlinear impairments on the proposed architecture. Meanwhile, a detailed literature analysis showed us that the combined quadruple impact of self phase modulation (SPM), cross phase modulation (XPM), FWM and SRS on the performance of bidirectional DWDM-PONs have never been researched up to now. In this paper, quadruple impact of SPM, XPM, FWM and SRS on the performance of both uplink channels (ULCs) and downlink channels (DLCs) of the formerly proposed DWDM-PON has been analyzed with simulations. Simulations have been performed in O-band region for ULCs and in C-band region for DLCs of 2 × 15- and 2 × 63-channel DWDM-PONs having 12.5 GHz, 25 GHz, 50 GHz, 100 GHz equally-spaced channels. The quadruple impact of optical nonlinear impairments on the DWDM-PON performance has been analyzed with signal-to-crosstalk ratio (SXR) simulations performed under varying channel input powers and channel lengths. Results show that under the quadruple nonlinear impact reliable bidirectional transmission with an SXR over 23 dB can be achieved for channel input powers below 0.58 mW and 0.16 mW in 2 × 15- and 2 × 63-channel DWDM-PONs, respectively, for all channel spacing values and 25 km transmission lengths. Moreover, results also imply that variations in channel lengths do not significantly affect SXR at both ULCs and DLCs of 2 × 15- and 2 × 63-channel DWDM-PONs for lengths exceeding 50 km. The thorough analysis presented in the paper will give a new insight for analysis of conventional and next generation PONs. [ABSTRACT FROM AUTHOR]

This research explores Wavelength Division Multiplexing Passive Optical Networks (WDM-PON) with Erbium-Doped Fiber Amplifier (EDFA) to meet the growing demand for highbandwidth applications. Using Optsim software, the proposed system is simulated for 4-channels WDMPON. The paper presents a comparison of WDMPON performance with and without EDFA amplifiers. It is to be proven that in inclusion of EDFA in the WDM-PON system will significantly improve the system's output power, reduce bit error rate (BER) and enhance the quality factor (Q-factor) with enhanced input parameters like higher fiber length up to 50 Km. The area of EDFA will also be optimized for improving system performance. The bitrate will also be increased to meet modern requirements of higher bandwidth. With EDFA, the WDM-PON system will perform better in the terms of error rate and signal amplification. The design involves parameters like bitrate, laser power, fiber length, modulation type, attenuated power, etc. WDM-PON with EDFA shows great potential for applications like high-speed data transmission systems for Internet applications. System is to be designed for higher bitrate with dispersion compensation and higher fiber length. The Goal is to achieve lower BER even at high distance of communication. [ABSTRACT FROM AUTHOR]

Abstract Solar cells are increasingly being utilised for both energy harvesting and reception in free‐space optical (FSO) communication networks. The authors focus on the implementation of a mid‐band p‐In0.01Ga0.99 N/p‐In0.5Ga0.5 N/n‐In0.5Ga0.5 N (PPN) solar cell, boasting an impressive 26.36% conversion efficiency (under 1.5AM conditions) as a receiver within an indoor FSO communication network. Employing a solar cell with dimensions of 1 mm in length and width, the FSO system underwent simulation using Optisystm software, while the solar cell's behaviour was simulated using SCAPS‐1D. The received power from the solar cell was then compared to that of four commercially available avalanche photodiode (APD) receivers. Exploring incident wavelengths spanning 400–700 nm within the visible spectrum, across transmission distances of 5, 10, 15, and 20 m, the study presented current‐voltage (IV) and power‐voltage curves. Notably, the InGaN solar cell exhibited superior electrical power output compared to all commercial APDs. In conclusion, the findings underscore that augmenting received power has the potential to enhance FSO network quality and support extended transmission distances.

We present a passive RF to optical data transfer without a local oscillator using an atomic "Rydberg" receiver. We demonstrate the ability to detect a 5G frequency carrier wave (3.5 GHz) and decode digital data from the carrier wave without the use of a local oscillator to detect the modulation of the RF signal. The encoding and decoding of the data are achieved using an intermediate frequency (IF). The rubidium vapor detects the changes in the carrier wave's amplitude, which comes from the mixing of the IF onto the carrier. The rubidium vapor then upconverts the IF into the optical domain for detection. Using this technique for data encoding and extraction, we achieve data rates up to 238 kbps with a variety of encoding schemes. [ABSTRACT FROM AUTHOR]

Federated Learning (FL) is a decentralized machine learning method in which individual devices compute local models based on their data. In FL, devices periodically share newly trained updates with the central server, rather than submitting their raw data. The key characteristics of FL, including on-device training and aggregation, make it interesting for many communication domains. Moreover, the potential of new systems facilitating FL in sixth generation (6G) enabled Passive Optical Networks (PON), presents a promising opportunity for integration within this domain. This article focuses on the interaction between FL and PON, exploring approaches for effective bandwidth management, particularly in addressing the complexity introduced by FL traffic. In the PON standard, advanced bandwidth management is proposed by allocating multiple upstream grants utilizing the Dynamic Bandwidth Allocation (DBA) algorithm to be allocated for an Optical Network Unit (ONU). However, there is a lack of research on studying the utilization of multiple grant allocation. In this paper, we address this limitation by introducing a novel DBA approach that efficiently allocates PON bandwidth for FL traffic generation and demonstrates how multiple grants can benefit from the enhanced capacity of implementing PON in carrying out FL flows. Simulations conducted in this study show that the proposed solution outperforms state-of-the-art solutions in several network performance metrics, particularly in reducing upstream delay. This improvement holds great promise for enabling real-time data-intensive services that will be key components of 6G environments. Furthermore, our discussion outlines the potential for the integration of FL and PON as an operational reality capable of supporting 6G networking. [ABSTRACT FROM AUTHOR]

With the continuous increase in data traffic and enormous consumption of data in terms of video on demand services and cloud computing, there is an increasing demand for high speed and high sensitivity short reach receivers for passive optical networks (PON) access network which are point to multi‐point networks. Avalanche photodiodes (APD) are the standard receivers in PON networks due to their high sensitivity and low cost. However, it is currently not clear if they can provide high bandwidth above 40 GHz with good performance (gain, noise, etc.). Furthermore, standard PIN photodiodes do not provide sufficient sensitivity for PON networks. Therefore, in this article a SOA‐UTC receiver is proposed, which is a photonic integrated circuit (PIC) comprising a semiconductor optical amplifier (SOA) for optical preamplification and a high‐speed uni‐travelling‐carrier (UTC) photodiode for opto‐electronic conversion. A very high responsivity of 140 A W−1 is demonstrated, with a polarization dependent loss (PDL) around 1 dB and a 3 dB bandwidth of 48 GHz, which is very promising for future PON network with 50 Gbit s−1 capacity and above. [ABSTRACT FROM AUTHOR]

The rapid development of the Industrial Internet of Things (IIoT) and its application across various sectors has led to increased interconnectivity and data sharing between devices and sensors. While this has brought convenience to users, it has also raised concerns about information security, including data security and identity authentication. IIoT devices are particularly vulnerable to attacks due to their lack of robust key management systems, efficient authentication processes, high fault tolerance, and other issues. To address these challenges, technologies such as blockchain and the formal analysis of security protocols can be utilized. And blockchain-based Industrial Internet of Things (BIIoT) is the new direction. These technologies leverage the strengths of cryptography and logical reasoning to provide secure data communication and ensure reliable identity authentication and verification, thereby becoming a crucial support for maintaining the security of the Industrial Internet. In this paper, based on the theory of the strand space attack model, we improved the Fiber Channel Password Authentication Protocol (FACP) security protocol in the network environment based on symmetric cryptography and asymmetric cryptography. Specifically, in view of the problem that the challenge value cannot reach a consensus under the symmetric cryptography system, and the subject identity cannot reach a consensus under the asymmetric cryptography system, an improved protocol is designed and implemented to meet the authentication requirements, and the corresponding attack examples are shown. Finally, the effectiveness and security of the protocol were verified by simulating different networking environments. The improved protocol has shown an increase in efficiency compared with the original protocol across three different network configurations. There was a 6.43% increase in efficiency when centralized devices were connected to centralized devices, a 5.81% increase in efficiency when centralized devices were connected to distributed devices, and a 6.32% increase in efficiency when distributed devices were connected to distributed devices. Experimental results show that this protocol can enhance the security and efficiency of communication between devices and between devices and nodes (servers, disks) in commonly used Ethernet passive optical network (EPON) environments without affecting the identity authentication function. [ABSTRACT FROM AUTHOR]

A novel modulation, that is, multi‐ary polarization shift keying (PolSK) modulation is proposed for wavelength division multiplexing passive optical networks (PONs) to achieve colorless optical network units. The downstream signal applies the proposed multi‐ary PolSK to eliminate the induced crosstalk to the remodulated amplitude shift keying upstream signal. Different from traditional PolSK, there are more than two polarization states in the proposed multi‐ary PolSK, so it provides higher bit rates and spectra efficiency. Four‐ary and 6‐ary PolSK are demonstrated and evaluated by simulation. The results show the proposed multi‐ary PolSK supports high‐speed downstream signal in future PONs with very low crosstalk induced to the remodulated upstream signal. [ABSTRACT FROM AUTHOR]

The capacity of passive optical networks (PONs) is continuously increasing, and it has been standardized up to 50 Gbit/s. The two main standardization organizations, IEEE and ITU-T, are actively working on the next-generation PON, which appears to be a 100G-PON still based on intensity modulation. Even though direct detection would be preferred for its cost and simplicity, the choice of coherent detection seems inevitable when the bit rate reaches 200–400 Gbit/s, specifically to guarantee the optical power budget requirement of an access network. The introduction of coherent systems in the PON scenario, allowing high-power-budget performances, should encouragetelecom operators to merge the metro and access networks into a single domain. This paper analyzes the mentioned metro + PON convergence scenario with experimental results focusing on a 400 Gbit/s fully coherent transmission (50 GBaud PM-16QAM). We characterize three different transceivers, two of which are pre-commercials. We perform experimental demonstrations, with real urban fiber and laboratory set ups, of the metro–access convergence network in terms of the minimum OSNR value of the metro path, producing an acceptable optical power budget within the access network. Our work demonstrates feasibility of merging the metro–access network by using currently coherent optical transceivers for PON applications. [ABSTRACT FROM AUTHOR]

Solar cells are increasingly being utilised for both energy harvesting and reception in free‐space optical (FSO) communication networks. The authors focus on the implementation of a mid‐band p‐In0.01Ga0.99 N/p‐In0.5Ga0.5 N/n‐In0.5Ga0.5 N (PPN) solar cell, boasting an impressive 26.36% conversion efficiency (under 1.5AM conditions) as a receiver within an indoor FSO communication network. Employing a solar cell with dimensions of 1 mm in length and width, the FSO system underwent simulation using Optisystm software, while the solar cell's behaviour was simulated using SCAPS‐1D. The received power from the solar cell was then compared to that of four commercially available avalanche photodiode (APD) receivers. Exploring incident wavelengths spanning 400–700 nm within the visible spectrum, across transmission distances of 5, 10, 15, and 20 m, the study presented current‐voltage (IV) and power‐voltage curves. Notably, the InGaN solar cell exhibited superior electrical power output compared to all commercial APDs. In conclusion, the findings underscore that augmenting received power has the potential to enhance FSO network quality and support extended transmission distances. [ABSTRACT FROM AUTHOR]

We propose a novel approach to mitigate the limitations of high-speed Passive Optical Networks (PONs) by introducing an all-optical processor. This solution addresses the escalating demand for higher data rates and improved performance in future access networks. The all-optical processor leverages optical signal processing to enhance system efficiency and reduce power consumption compared to traditional electrical methods. Specifically, we explore the processor's dual functionality in performing all-optical equalization and chromatic dispersion compensation. Our research includes a comprehensive analysis of the processor's design, operational principles, and system validation through extensive simulation studies, demonstrating significant improvements in signal quality and overall network performance. The results indicate that the all-optical processor not only relaxes the DSP and power requirements but also outperforms the more sophisticated digital counterpart methods. [ABSTRACT FROM AUTHOR]

The emerging high-bandwidth services of 6G, such as high-definition video transmission and real-time interaction, have promoted the progress of the fiber optic access network industry, driving its development towards the next-generation PON with higher speed and larger system capacity. In response to the future requirements of 200 Gb/s/λ PON for both 20 km and 30 km downlink transmission scenarios, this paper proposes a Simplified Volterra Equalization (SVLE) scheme based on Nyquist PAM4 single-sideband modulation direct detection (SSBM-DD) scheme. In order to verify its advantages, the IQ-modulated Kramers–Kronig reception (KK) scheme is introduced for comparison. Simulation validation platforms for two schemes are conducted, and the performance comparison of the SVLE and KK schemes is carried out. In both, the impact of the carrier signal power ratio (CSPR) on receiver sensitivity, the influence of input optical power on power budget and receiver sensitivity, and the tolerance of receiver sensitivity to the linewidth of the DFB laser are investigated in the simulation. Finally, a comprehensive comparison of the two schemes is presented in terms of system performance, cost, and DSP complexity. In the 20 km downlink transmission scenario, the SVLE scheme outperforms the KK scheme by 4.9 dB in terms of power budget. The total number of multiplications of the SVLE scheme is 37, while that of the KK scheme is 4358. Therefore, the DSP complexity of the SVLE scheme is much lower than that of the KK scheme. The results of the comparison demonstrate that, in downlink transmission scenarios, the SVLE scheme is more suitable than the KK scheme as it exhibits a higher power budget, lower DSP complexity, and lower cost. Consequently, the proposed SVLE scheme could be a highly promising solution for future ultra-high-speed PON downlink transmission. [ABSTRACT FROM AUTHOR]

Recently, extensive research has been conducted to explore the utilization of machine learning (ML) algorithms in various direct-detected and (self)-coherent short-reach communication applications. These applications encompass a wide range of tasks, including bandwidth request prediction, signal quality monitoring, fault detection, traffic prediction, and digital signal processing (DSP)-based equalization. As a versatile approach, ML demonstrates the ability to address stochastic phenomena in optical systems networks where deterministic methods may fall short. However, when it comes to DSP equalization algorithms such as feed-forward/decision-feedback equalizers (FFEs/DFEs) and Volterra-based nonlinear equalizers, their performance improvements are often marginal, and their complexity is prohibitively high, especially in cost-sensitive short-reach communications scenarios such as passive optical networks (PONs). Time-series ML models offer distinct advantages over frequency-domain models in specific contexts. They excel in capturing temporal dependencies, handling irregular or nonlinear patterns effectively, and accommodating variable time intervals. Within this survey, we outline the application of ML techniques in short-reach communications, specifically emphasizing their utilization in high-bandwidth demanding PONs. We introduce a novel taxonomy for time-series methods employed in ML signal processing, providing a structured classification framework. Our taxonomy categorizes current time-series methods into four distinct groups: traditional methods, Fourier convolution-based methods, transformer-based models, and time-series convolutional networks. Finally, we highlight prospective research directions within this rapidly evolving field and outline specific solutions to mitigate the complexity associated with hardware implementations. We aim to pave the way for more practical and efficient deployment of ML approaches in short-reach optical communication systems by addressing complexity concerns. [ABSTRACT FROM AUTHOR]

Mode division multiplexing (MDM) is very competent next generation multiplexing technique and is becoming popular among researchers these days. In this research article, an integrated passive optical network (PON) using MDM and wavelength division multiplexing (WDM) is proposed at 25 Gbps over 3 km multimode fiber (MMF) link distance. For MDM, diverse Laguerre–Gaussian (LG) such as LG12, LG15, LG18, LG111 and LG114 are incorporated and also for cost reduction, vertical cavity surface emitting laser (VCSEL) is located in optical line terminal (OLT). Performance of diverse advanced modulations such as compressed spectrum return to zero (CSRZ), duo-binary return to zero (DRZ) and modified duo-binary return to zero (MDRZ) is evaluated and compared with non-return to zero (NRZ) in terms of Bit error rate (BER) at varied MMF link lengths. Results revealed that CSRZ performance stand out and NRZ provide worst performance. [ABSTRACT FROM AUTHOR]

In the development of ethernet passive optical networks (EPONs), quality of service (QoS) support and fairness per optical network unit (ONU) are crucial issues. However, making an elaborate analysis of the existing prediction-based bandwidth allocation algorithm, light load penalty, low prediction precision are pointed out. We present an improved dynamic bandwidth pre-allocation algorithm (R-DBA), which employs recurrent neural network (RNN) to predict the high-priority service traffic in EPON. And we introduce mixed integer linear programming (MILP) for optimally building DBA algorithm. This algorithm achieves the prediction of the high-priority service traffic by RNN during the waiting time and supports bandwidth pre-allocation, thus ensuring the fairness of the bandwidth allocation. [ABSTRACT FROM AUTHOR]

In this paper, we have proposed and demonstrated a 100 Gbps data transmission system over hybrid single mode fiber (SMF)-free space optics (FSO) link using optical comb lines in wavelength-division-multiplexing technique. A continuous wave laser, two dual drive Mach-Zehnder modulators and four electrical attenuators are employed to generate optical frequency comb lines (OFCL). The OFCL generator generates 52 comb lines by optimizing biasing voltages. The OFCL lines with a side mode suppression ratio of ∼ 50dB and flatness ∼∼ 0.01dB are generated and used as an optical carrier in the proposed system. The performance of the system is investigated in different weather conditions, such as clear weather, hazy weather, heavy rain, light fog, moderate fog, and heavy fog. [ABSTRACT FROM AUTHOR]

The structure of a cloud is three-dimensional (3-D). Nevertheless, cloud research is predominantly developed in one-dimensional (1-D) hypothesis from passive optical satellite measurements. Cloud retrieval algorithms typically do not consider the parallax displacement of clouds in multi-view images. Inversion of cloud properties based on two-dimensional (2-D) coordinates cannot solve multi-view radiation changes which are caused by macro-structure of a cloud in 3-D space. In this study, we included the 3-D structure of clouds by repositioning cloud pixels within a 3-D coordinate system utilizing the directional polarization camera (DPC) data before conducting cloud property retrieval. It is followed by identification of location of cloud in each observational view's image plane. Observational paths of clouds are rebuilt at each observational view. Furthermore, computer graphics methods are employed to establish spatial relationship among different cloud observational paths. The radiational and geometrical information are relocated in unified 3-D sub-pixel space. Finally, 3-D cloud radiation information could be applied to retrieve cloud properties. The case results demonstrate that our method can effectively reduce mixed pixels of clouds and clear sky by 5.79% while decrease indistinguishable pixels in cloud phase classification by 2.11%. It leads to an enhancement in the classification accuracy of water clouds and ice clouds by 3.30% and 4.03%, respectively. Therefore, it is concluded that considering the impact of cloud structure before retrieval would significantly improve accuracy. [ABSTRACT FROM AUTHOR]

Hybrid Passive optical networks provide better communication link with high data rate and low power consumption. Hybrid system is more secured system for large bandwidth application. Here, in this paper, Wavelength Division Multiplexing and Time Division Multiplexing (WDM-TDM) both are used to establish a better communication system. Pump laser used here to transfer the energy from an external source to a gain medium of a laser. The performance can be observed by the observation of Q-Factor, BER value and SNR value. For simulation and optimization purpose OptiSystem software is used here. [ABSTRACT FROM AUTHOR]

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Diffractive neural networks (DNNs) are emerging as a new machine learning hardware based on optical diffraction with parallel and high‐throughput information processing. The optical inputs to DNNs are spatially modulated by propagating through passive diffractive layers that work in succession to achieve an inference. Herein, visible wavelength classification using single‐ and two‐layer DNNs fabricated using direct laser writing is demonstrated. The proposed DNN approach accepts the point spread function of two different wavelengths modeled after a microscope objective as the input and modulates the input field toward the target detector for classification. Of the three models trained to classify different wavelength pairs, the highest performance observed is for the classification of 561 and 785 nm, achieving over 90% accuracy. This work demonstrates the potential of all‐optical artificial neural networks for applications requiring visible wavelengths, from visible light beam shaping to spectral analysis and optical imaging. [ABSTRACT FROM AUTHOR]

With the development of the Internet of Things, cloud networking, and 4K/8K high-definition video, global internet traffic has seen a dramatic increase. This surge in traffic has placed higher demands on the performance of optical networks, featuring higher data rates, lower latency, and lower cost. The passive optical network (PON) is a representative scenario of optical access networks. Issues such as burst-mode detection in upstream PON scenarios, flexible rate allocation in downstream scenarios, and the simplification of hardware complexity at the optical network unit (ONU) side have attracted considerable attention. Compared to intensity modulation/direct detection (IM/DD), a recently proposed coherent PON incorporates a local oscillator laser at the receiver, enabling superior receiver sensitivity, spectrally efficient modulation, linear optical field recovery, and flexible channel selection. These features significantly enhance the flexibility and data rates of PON systems. This paper provides a comprehensive review of the development of coherent PONs, particularly in aspects of preamble design for burst-mode detection in upstream scenarios, the design of flexible rate PONs in downstream scenarios, and solutions for reducing hardware complexity at the ONU side.

The rapid evolution of passive optical network (PON) technologies has been driven by the necessity to accommodate 5th-generation system requirements. This research introduces a PON wavelength division multiplexing-based optical transmitter that is improved in both fiber link and bit rate. The transmitter is designed to connect many clients to a single-mode optical fiber. The optical transmitter under consideration is designed to provide an optimum data rate up to 20 Gbps per user. The data is modulated using a 2-bit per symbol Quadrature Phase Shift Keying (QPSK), and an M-array pulse coder. The R.F. signal is optically modulated during the optical system stage using a Mach–Zehnder external modulator supplied with an optical carrier generated by a vertical cavity surface emitting laser (VCSEL). Two PON configurations are devised in this context: initially, 16 VCSELs spanning 193.1–194.6 THz with a 10 GHz separation are utilized to modulate 16 data sources with 16 MZM. In contrast, in the second configuration, to reduce input laser power and system complexity, 16 data consumers share a single 193.1 THz VCSEL. Simulations of the performance measurements were conducted by Optisystem 19 for both configurations. The initial system configuration permits 20 Gbps transmission to 120 km with a Q-factor of at least 6. The power penalty of this configuration was reduced from − 970 to − 930 dB. The second configuration guarantees the dependability of data transmission over a distance of 100 km. The maximal Q-factors for the first and second configurations are 12 and 10, respectively, at a distance of 20 km. It has been established that the ideal input bias current for a VCSEL is 2 mA. The effects of the quadrature phase shift keying modulation QPSK is clearly appeared, as the current results are surpassed the peer publications regarding the utmost achievable fiber link length, Q-factor and supported data rate. [ABSTRACT FROM AUTHOR]

A polarized bidirectional reflectance distribution function (pBRDF) matrix was developed based on the two-scale roughness theory to provide consistent simulations of fully polarized microwave emission and scattering, required for the ocean–atmosphere-coupled radiative transfer model. In this study, the potential of the two-scale pBRDF matrix was explored for simulating ocean full-polarization backscattering and bistatic-scattering normalized radar cross sections (NRCSs). Comprehensive numerical simulations of the two-scale pBRDF matrix across the L-, C-, X-, and Ku-bands were carried out, and the simulations were compared with experimental data, classical electromagnetic, and GMFs. The results show that the two-scale pBRDF matrix demonstrates reasonable dependencies on ocean surface wind speeds, relative wind direction (RWD), geometries, and frequencies and has a reliable accuracy in general. In addition, the two-scale pBRDF matrix simulations were compared with the observations from the advanced scatterometer (ASCAT) onboard MetOP-C satellites, with a correlation coefficient of 0.9634 and a root mean square error (RMSE) of 2.5083 dB. In the bistatic case, the two-scale pBRDF matrix simulations were compared with Cyclone Global Navigation Satellite System (CYGNSS) observations, demonstrating a good correlation coefficient of 0.8480 and an RMSE of 1.2859 dB. In both cases, the two-scale pBRDF matrix produced fairly good simulations at medium-to-high wind speeds. The relatively large differences at low wind speeds (<5 m/s) were due probably to the swell effects. This study proves that the two-scale pBRDF matrix is suitable for the applications of multiple types of active instruments and can consistently simulate the ocean surface passive and active signals. [ABSTRACT FROM AUTHOR]

Passive differential optical absorption spectroscopy (DOAS) is widely used to monitor the three-dimensional distribution of atmospheric pollutants. However, the observational and retrieval accuracy of this technique is significantly influenced by the precise wavelength calibration of solar spectra. Current calibration methods face challenges in automation when dealing with complex remote-sensing conditions. We introduce a novel automatic wavelength calibration algorithm for passive DOAS based on sequence-matching technology to estimate the spectral parameters of the spectrometer channels, integrating advanced processing measures such as feature structure enhancement and sub-pixel interpolation. These measures significantly reduce the dependency on reference spectrum resolution and accurately correct even minor spectral shifts. We perform sensitivity experiments using synthetic spectra to determine optimal retrieval configurations, followed by field tests at four cities on the Yangtze River Delta, China, to calibrate and compare passive DOAS instruments of various resolutions. Comparative verification in these field studies demonstrated that our algorithm was suitable for rapid spectral calibration within a wider resolution range of 0.03 nm to 0.1 nm with a wavelength inversion error < 0.01 nm. This highlights the applicability and calibration precision of our algorithm. [ABSTRACT FROM AUTHOR]

In a fluorescence microscope, passive autofocus processing provides the best-focused cellular image in optical visualization during image collection. The steep focus curve is essential to high throughput microscopy for the application of cell images by reducing the number of stack image acquisitions to be focus-measured. The proposed scheme combines the non-parametric blur ratio computed by the two-step Otsu's threshold method to region of interest (ROI)-based autofocus measures based on the conventional sharpness metrics. The blur ratio expedites the gentle focus curve caused by arbitrary plane selection of an out-focused image to be segmented among stack images. It makes up for irregular focus computation by the improper threshold value of Otsu's method by bright big cells and epithelial debris. Also, the proposed blurriness curve of stack images identifies coarse and fine search areas in variable step-sized autofocus search algorithms, which decreases the number of image collection for calculating the focus metrics. In computer simulations with nuclei cell images containing U2OS cells stained with Hoechst from the Broad Bioimage Benchmark Collection (BBBC), the proposed autofocus algorithm yields superior sharpness performance of focus curve over the schemes applying the entire image and using focus ROI by Otsu's method. Four types of cellular fluorescence images are evaluated in terms of normalized focus curves and quantitative criteria of steepness, sharpness ratio, and sensitivity. Additionally, the performance excellence of the proposed autofocus algorithm is assessed by testing the rule-based search algorithm with a varying search size and adapting the blurriness curve in terms of the quantitation of autofocus speed (number of stack image acquisitions) and accuracy of focus position (not to lose best focus position). [ABSTRACT FROM AUTHOR]

The unique advantage of orbital angular momentum (OAM) provides a novel approach to breaking through the limitations of high‐capacity and long‐distance transmission in the conventional radio‐overfiber passive optical network (RoF‐PON) hybrid access network. Introducing the OAM division multiplexing (OAM‐DM) based on Laguerre–Gaussian (LG) beams into the RoF‐PON, an innovative multidimensional system architecture is proposed, which integrates with polarization‐division multiplexing (PDM), wavelength‐division multiplexing (WDM), and orthogonal frequency‐division multiplexing (OFDM) technologies. Successful long‐distance transmission of both the downstream 40 GHz radio OFDM signal and the upstream 40 Gbps on‐off keying (OOK) signal over 80 km are achieved. Additionally, at the optical network unit side, low‐cost upstream carrier re‐modulation technology and flexible access for both wired and wireless signals are realized. The proposed RoF‐OAM‐DM‐PDM‐WDM‐OFDM‐PON architecture offers a dependable solution for high‐capacity and low‐cost future communication systems, holding great importance in achieving flexible access networks. [ABSTRACT FROM AUTHOR]

This paper presents the experimental results of a novel radio-over-fiber (RFoF) architecture that is capable of transmitting data at 20 Gb/s over a 600 km fiber. Such high bit rates required by 5G systems for long-haul communication. This is accomplished by overcoming the limitation of single mode fibers (SMF) of power attenuation and chromatic dispersion. This is achieved by interspersing sections of the SMF with a dispersion compensating filter (DCF) and embedding midway of the fiber length with chirped fiber Bragg grating (CFBG). Moreover, the proposed approach is shown to enhance the total bandwidth over a long-haul gigabit passive optical network (GPON) using integrated channel coarse wavelength division multiplexing (CWDM). In the experiment, a 64-quadrature amplitude modulation (64-QAM) signal was modulated onto CWDM signal. With the proposed RFoF architecture the signal power received over a 600 km fiber is greater than a conventional optical architecture by 19 dB for identical applied input optical power of 20 dBm. This translates to significant power savings that can be achieved with the proposed architecture over existing architectures that should reduce the carbon footprint of long-haul optical communications systems. The optical receiver is shown to have a sensitivity of −28.3 dBm for a bit-error rate (BER) of 10−9. These results demonstrate the viability of the proposed RFoF architecture in providing significant improvement in the bit rate over a transmission distance. [ABSTRACT FROM AUTHOR]