Optical Communication Networks Research Articles

Review on nonlinearity effect in radio over fiber system and its mitigation

Abstract Modern communication generation for high data rate requirement is fifth generation. The fifth generation has many advantages like low delay, high spectrum availability, high reliability, low jitter, and more capacity. To combat with the high capacity and high data rate requirement, optical fiber helps in the backhaul of 5G network. When fiber is used as a mode of propagation, many nonlinearities arises. This nonlinearity effect in the optical fiber communication is one of the most undesirable phenomena for the modern communication system which results in harmonic distortion, intermodulation distortion, phase distortion, and adjacent channel interference, etc. In most fiber optic communication systems, the major fiber nonlinear effect is the Kerr nonlinearity and Scattering effect that produced due to the variation of refractive index due to signal intensity. To minimize the effect of nonlinear distortion, some techniques are used which considerably improve the transmission capacity by reducing or compensating the effect of nonlinear distortion along with minimal infrastructure modifications and minimum cost for implementation. To overcome the effect of nonlinearity, fiber nonlinearity mitigation techniques are preferred to achieve the significant performance gains. Mitigation techniques can be implemented to improve and optimize the performance of optical communication network. In this paper, a brief description of the fiber nonlinearity effect and a review of various fiber nonlinearity compensation techniques are described.

Modelling and Simulation Analysis of Routing Algorithms in Multichannel Optical Communication Networks

In this paper, it is considered the broadband backbone optical networks with wavelength routing and circuit switching used to build long-range wide area networks. In this type of network, if there is an available and acknowledged connection request, it is necessary to determine the optimal path between the optical communication nodes in the network. This also requires the assignment of an optimal set of wavelengths along the selected route between these nodes. This paper takes into account the multichannel optical communication networks with spectral multiplexing. Four different routing algorithms are modeled and analyzed for which their weight functions are determined to take into account various factors, such as the total distance of the individual routes, the total number of available wavelengths for a given route and how many of them are available for use. It is studied and compared the performance of the proposed algorithms in a multichannel optical network in terms of blocking probability.

Remotely Pumped All-Optical Wavelength Conversion for WDM-PON-Based Access-Metro Convergence

Access-metro convergence networks (AMCN) have been proposed as a future optical communication network to realize flexible and dynamic bandwidth allocation. An AMCN requires transceivers with different wavelengths for the optical network units (ONUs). This causes an increase in production costs. Although an all-optical wavelength converter (AOWC) mitigates this issue, the AOWC increases the installation cost because it consists of many expensive optical devices. We propose the use of a remotely pumped AOWC (RP-AOWC) with an AMCN. The proposed technique can reduce the number of pump light sources in the AOWC. This paper demonstrates this reduction in the number of light sources and the feasibility of wavelength conversion using pump light propagation. We calculate the reduction in the number of pump sources and the number of transceiver types caused by the use of RP-AOWC and experiment with the wavelength conversion using pump light propagation.

An energy-efficient recovery algorithm for the free space optical communications network via reflections

Free space optical (FSO) communication is a very attractive solution to substitute or complement radio frequency-based wireless technologies for providing high-speed wireless connections. FSO-based network consists of a lot of optical nodes, whose transmission power is concentrated in a narrow volume. Considering the directionality of FSO communications, the outage of a node in the network may result in reduced link connectivity and availability, thus causing coverage hole. Once the coverage hole, the accuracy of network monitoring data would not only be reduced, but much of the not-yet-used resource would also be abandoned in the network resulting in energy waste. In this paper, we propose an energy-efficient recovery algorithm for FSO network based on reflections. The proposed algorithm adopts the classified repair mode based on the communication conditions prior to dying of the node. If the dead node is a relay node, the mirror node is used as the repair node in order to reduce the energy consumption of data forwarding, and an evaluation model is established by combining the coverage and the energy to determine the repair location. However, if the dead node is not a relay node, the ordinary node is used as repair node. The location of the repair node is found based on the coverage and the geometric relationship to ensure the maximum coverage. The simulation results show that, the proposed algorithm not only sustains coverage but also reduces the network energy consumption and prolongs the network's lifetime.

Impact of optimized pulse shaping on optical transmission performance in the availability of different dispersion maps

One of the most detrimental effects of an optical communication network that can strongly restrict the bit rate and thus reduce the transmission performance is the nonlinear effect. In this work, the effect of the optimized pulse on the optical transmission system with different dispersion maps i.e. post, pre, and symmetric dispersion compensation for 240 km is investigated. Furthermore, the system performance in terms of max quality factor (Q-factor) is performed under the influence of input power changing and applying bit rate equal to a 40 Gb/s. The results state that the optimized shaper brought an improvement in the performance compared to other pulse shapes at the same conditions. Also, the post-compensation shows better performance compared to pre and symmetrical at the same time. For instance in the case of post compensation at 10 dBm input power and 240 km distance, the optimized pulse shape offered better performance compared to others where the Q-factor equal to 67.65. As well as it is clear when NRZ, RZ and Sine pulse are used, the quality factors were decreased to 66.53, 50.92, 51.34 sequentially at the same input conditions.

A hybrid next-generation passive optical network and visible light communication for future hospital applications

The advancement in the latest healthcare technologies have shown a growing interest in 10/10 Gbps per channel hybrid next generation passive optical network (NG-PON) and visible light communication (VLC) networks to achieve the aim of future hospital applications. This paper investigates the use of hybrid time and wavelength division multiplexing PON (TWDM-PON), wavelength division multiplexing optical code division multiple access PON (WDM-OCDMA PON) using zero cross-correlation (ZCC) code and VLC for the hospitals scenario. The proposed bidirectional system is investigated for four TWDM, six WDM-OCDMA and three VLC information channels in terms of variable fiber length, bit rate, different OCDMA codes and multi-hospital systems. It is investigated that upstream channels performs better than downstream channels and provides the successful 10/10 Gbps hybrid system over 50 km fiber and 10 m VLC link serving 53 users in single hospital system. It also provides the high eye-height, optical signal to noise ratio (OSNR) and received power. Moreover, the performance of the proposed system can be further enhanced by using modified quadratic congruence (MQC) code and high transmission power. Also the comparative analysis with existing systems show the superiority of the hybrid NG-PON/VLC system using fiber/wireless links over the conventional radio access networks in healthcare applications.

Mid-infrared broadband all-optical wavelength converter in Ge20Sb15Se65 photonic crystal fiber with flattened dispersion

A chalcogenide photonic crystal fiber (PCF) with flattened dispersion and high nonlinearity in mid-infrared (mid-IR) based on a triangular and circular lattice hybrid cladding structure is proposed. The structural parameters of the PCF are optimized by the full-vectorial finite-difference method. The numerical simulation results show: when d1 = 0.4 µm, d2 = 0.16 µm, d3 = 0.04 µm, Ʌ1 = 0.88 µm, Ʌ2 = 0.8 µm, Ʌ3 = 0.5 µm, the flatten and low dispersion is obtained in the wavelength range of 3.8–5 µm. The dispersion value is between ± 1.2 (ps/nm/km), and the maximum nonlinear coefficient is as high as 2464.2 km-1 W-1 at 2.5 µm. Based on the four-wave mixing (FWM) effect in the proposed PCF, the all-optical wavelength conversion performance is numerically analyzed. When the pumping wavelength is 4.02 µm, the 3 dB conversion bandwidth can reach 4833 nm (from 2.737 µm to 7.57 µm), and the maximum wavelength conversion efficiency is 12.12 dB. The proposed all optical wavelength converter is having large bandwidth and high conversion efficiency in mid-IR band due to the flat dispersion and high nonlinearity of the PCF, which has potential application in future space optical communication network and mid-IR photonic.

Analytical Solution of FSO-Mimo System Peformance Using DWDM Optical Communication

Now days, in optical communication network challenge requirement are a high quality factor, good performance in terms of parameters like Bit Error Rate (BER), Eye Diagram. An objective of this paper, to analysis the attenuation value for a haze and normal weather condition respectively, and analysis, performance result of the different optical system has been compared in terms of received signal strength and quality factor of the different haze atmosphere. In this proposed paper used FSO with SISO and FSO-MIMO system for measuring the Q-factor and BER for various data link in different atmosphere. Finally, simulation result shows that the improved FSO link over the existing technique in terms of both the parameter signal power strength and quality factor.

Performance Analysis of Hybrid Radio Frequency and Free Space Optical Communication Networks with Cooperative Spectrum Sharing

This paper investigates the impact of cooperative spectrum sharing policy on the performance of hybrid radio frequency and free space optical wireless communication networks, where primary users and secondary users develop a band of the same spectrum resource. The radio frequency links obey Nakagami-m distribution with arbitrary fading parameter m, while the free space optical link follows gamma-gamma distributed atmospheric turbulence with nonzero pointing error. Because the secondary users access the spectrum band without payment, their behavior needs to be restricted. Specifically, the power of the secondary users is dominated by the tolerable threshold of the primary users. Considering both heterodyne and intensity modulation/direct detection strategies in optical receiver, the performance of optical relaying networks is completely different from that of traditional networks. With the help of bivariable Fox’s H function, new expressions for cumulative distribution function of equivalent signal to noise ratio at destination, probability density function, outage probability, ergodic capacity and symbol error probability are built in closed forms.

Extinction Ratio and the Fiber Optic Transmission Networks

In the fiber optic communication network for example,- FTTH, EPON, NBN, OTN and so on, the most important components are fiber length between transmitter and receiver point. So, to make, cheap and meaningful communication through optical fiber it must be required to calculate how and what amount of signal is transmitted with the given length of the fiber. Finally, it is said that the optical fiber network have several limitations like extension ratio. So, it is necessary to investigate its affect on the performance of the Optical Network. This research is based on simulation by OptiSystem 0.17 on the basis of Dense wavelength division multiplex (DWDM) technology, Erbium Doped Fiber Amplifier (EDFA), dispersion Compensating Fiber (DCF) and single mode fiber of length 50–100 km.

Connection availability for optical communication networks employing dedicated protection system

Designing a protection system for improvement of the availability of connections is an important issue in communication networks under resource constraints. Quantification of availability for networks is a fundamental design element of network-communication services. In this paper, we present a generalized mathematical model for connection availability of an optical communication network with a dedicated protection system. Specifically, the proposed model provides a closed-form relation of connection availability with the path availabilities for the M:N dedicated protection system using probability and combinatorics. We performed various numerical tests for protection systems with different path availabilities to demonstrate the plausibility of the model. To validate the model, Monte-Carlo (MC) simulation was carried out and MC simulation provides a good accordance with the theoretical model, satisfying the theoretical results with the reality. The test results can be used as a benchmark for any new model validation in future. The same model can be applied to similar problems related to probabilistic analysis in other areas.

High speed modulated wavelength division optical fiber transmission systems performance signature

This study presents modulated-wavelength division radio signals over fiber with mixed modulation techniques in the transmitter stage. Hybrid optical sources are used to achieve optimal performance and enhancement for an optical fiber communication network. The proposed modulation techniques work at a frequency of 250 GHz. Optical quadrature phase shift keying (OQPSK) and phase modulation (PM) techniques were merged to create OQPSKPM. This was in addition to the minimum shift keying (MSK) modulation scheme that was applied in the proposed model. The modulated wavelength division multiplexing design to four subscribers was examined with a single mode optical fiber at a 1550 nm wavelength. The proposed and previous simulation models were executed, investigated and measured on important operating parameter quantities that expressed the behavior of the optical fiber network in detail, like maximum quality factor, minimum bit error rate, and output power. The obtained simulation results demonstrated the priority of the proposed simulation model.

Generation of four-wave mixing in molybdenum ditelluride (MoTe2)-deposited side-polished fibre

In this work, we report the effect of four-wave mixing (FWM) in MoTe2 deposited on a side-polished fibre (SPF). The MoTe2 layer has a nonlinear coefficient of 17.368 W−1 km−1 at 1550 nm, while the coated SPF has a conversion efficiency of – 38 dB and output tuning range of 5 nm. The generated idlers from the induced FWM effect were observed to be highly stable with minimal peak fluctuations and only minor changes in their measured conversion efficiency. The proposed MoTe2 based SPF is thus a suitable device for inducing the FWM effect in an optical fibre laser cavity and could also serve to induce other non-linear optical effects for use in optical communications networks.

All-fiber narrow-bandwidth rectangular Optical filter with reconfigurable bandwidth and tunable center wavelength.

In this manuscript, a novel narrow-bandwidth rectangular optical filter based on multi-phase-shifted fiber Bragg grating (MPSFBG) is proposed. Using the local temperature control technology, the precise controllable phase shifts are introduced at different positions of the fiber Bragg grating (FBG). Therefore, the bandwidth of the MPSFBG-based filter with good shape factor can be reconfigured from 70 MHz to 1050 MHz by flexibly controlling the numbers and the positions of the phase shifts introduced in the MPSFBG. In addition, the center wavelength of the MPSFBG-based filter can be tuned through controlling the MPSFBG's environment temperature, and the tuning range of 22 GHz is realized. This is one of the best results for the narrow-bandwidth rectangular optical tunable filter with reconfigurable bandwidth. It can be widely used in the processing of reconfigurable signals in the optical communication networks and microwave photonics.

Multimode Interference Induced Optical Routing in an Optical Microcavity

AbstractThe photonic router is a key device in optical communication and quantum networks. Here, the results of a study of multi‐channel optical routing using optomechanical multimode interference in an optical microcavity are reported. The optomechanical system used here exhibits multi‐optical modes and a mechanical mode. Optomechanical induced transparency and absorption appear in the system due to the interference between different paths. It is shown that the system can be served as a three‐port routing in the red‐detuned region to rout photons from the input port to an arbitrarily selected output port with high routing efficiency by controlling the parameters corresponding to different interference paths.

Highly versatile near-infrared emitters based on an atomically defined HgS interlayer embedded into a CdSe/CdS quantum dot.

The availability of colloidal quantum dots with highly efficient, fast and 'non-blinking' near-infrared emission would benefit numerous applications, from advanced optical communication and quantum networks to biomedical diagnostics. Here, we report high-quality near-infrared emitters that are based on well known CdSe/CdS heterostructures. By incorporating an HgS interlayer at the quantum dot core/shell interface, we convert normally visible emitters into highly efficient near-infrared fluorophores. Employing thermodynamically controlled sequential deposition of metal and chalcogen ions, we achieve atomic-level precision in defining the thickness of the HgS interlayer (H). This manifests in 'quantized' jumps of the photoluminescence spectrum when H changes in discrete, atomic steps. The synthesized structures show highly efficient photoluminescence, tunable from 700 to 1,370 nm, and fast radiative rates of ~1/60 ns-1. The emission from individual CdSe/HgS/CdS colloidal quantum dots is virtually blinking free and exhibits nearly perfect single-photon purity. In addition, when incorporated into a light-emitting-diode architecture, these quantum dots demonstrate strong electroluminescence with a sub-bandgap turn-on voltage.

Design and modeling of double Panda-microring resonator as multi-band optical filter

In this paper, the behavior of light within a double stage developed add-drop ring resonator called a double Vernier Panda-ring resonator (DVPR) is investigated using the signal flow graph technique in the Z-domain and Mason’s gain rule. The system included a double stage of add-drop ring resonators that each add-drop ring is attached to two small lateral resonators. The light transmission through the DVPR system is studied and the system responses analyzed in terms of the fundamental physical properties such as the free spectral range (FSR), structural dispersion, group delay, finesse, Q-factor and resonant bandwidth. Based on the coupling strength between the add-drop rings and the small lateral resonators (indirect couplers), different values of extended FSR from 64 nm to 90 nm were realized in the wavelength region of 1.4–1.7μm. Results analyzed for four values of indirect coupling strengths and the optimum layout was determined, which led to realize of a FWHM as narrow as 0.47 nm, the extended FSR of 81 nm for the center wavelength of 1535 nm, the structural dispersion of 6.0 fs/pm and a group delay of 3.9 ps. The superiority of DVPR design rather than the conventional Vernier ring-based filter is in achieving several values for extended FSRs, which provides different optical communication channels. These characteristics of our proposed structure ensure the tuning of optical communication channels by means of an optical device, which is desirable in the optical communication networks

A Holistic Survey on Disaster and Disruption in Optical Communication Network

A Holistic Survey on Disaster and Disruption in Optical Communication Network

Research on Key Technologies of large capacity and long distance optical transmission systems

In recent years, with the rapid development of high-bandwidth applications and the rapid growth of Internet data services, the capacity of communication networks is growing rapidly. Optical fiber has become an ideal transmission medium for communication networks due to its advantages such as large bandwidth and low loss. Large-capacity and long-distance optical fiber communication networks have become the key research directions of optical communication systems. In this paper, the main technical means to achieve large-capacity and long-distance optical transmission are investigated. First, the application of orthogonal frequency division multiplexing (OFDM) technology in large-capacity transmission is briefly introduced, including its principle, main structure, advantages and disadvantages. Subsequently, wavelength division multiplexing (WDM) technology based on optical frequency comb is introduced. Finally, the methods to realize long-distance transmission are discussed, including Digital Backward Propagation (DBP), Phase-Conjugate Twin Wave (PCTW) and advanced modulation format.

Optical Channel Drop Filter Design Based on PCRR and Micro Cavity Resonator

Optical channel drop filter (OCDF) plays a key role in optical communication networks for filtering the individual wavelength among the group of channels in wavelength division multiplexing systems. There are several channel drop filters with different design mechanisms available in the literature, but those structure dimensions are not compact enough for the photonic integrated applications. Hence, in this paper, a compact and efficient OCDF is developed in the triangular lattice PC structure based on diamond-shaped photonic crystal ring resonator (PCRR) mechanism combined with micro cavity resonator (MCR). The developed OCDF is analysed for different operating wavelengths by considering the different positions of MCR around the main PCRR. Based upon the position of the MCR around PCRR, the three dropping wavelengths such as 1540 nm, 1550 nm, and 1570 nm are observed at the output waveguides with 100% dropping efficiency. Then the structural and performance parameter comparison is done between the proposed and existing structures in terms of device dimension, dropping efficiency, and quality factor. It is depicted through the results that the quality factor and the device dimension are better than that of the existing structures for 1550-nm wavelength.