Dense Wavelength Division Multiplexing Research Articles

Closed-form formula for unequal channel allocation to reduce FWM crosstalk in DWDM long-haul networks

Dense wavelength division multiplexing (DWDM) is considered as a mainstream solution for 5G optical transmission networks to confront increasing bandwidth demand. In such a dense multiwavelength system, the four wave mixing (FWM) non-linear effect limits the achievable transmission distance and channel capacity. For this reason, and to the best of our knowledge, a new unequal channel allocation (UCA) has been introduced in this paper based on new closed-form equations to reduce the FWM crosstalk in the DWDM optical long-haul network. The proposed channel allocation has been investigated based on several design parameters that affect FWM nonlinear crosstalk, such as total transmission distance, channel frequency spacing, the number of WDM channels, and the input power per channel. The suggested technique has further been compared with a previous model proposed by other authors to prove the effectiveness of this work. The simulation results have been examined and validated by analysing the optical spectrum analyser and the power of the FWM spectral products. Results demonstrate the reliability and the efficiency of the developed method.

The KM3NeT Broadcast optical system network

The optical data transport system of the KM3NeT neutrino telescope at the bottom of the Mediterranean Sea will serve more than 6000 optical modules in the detector arrays with a point-to-point optical connection to the control stations onshore. The ARCA and ORCA detectors of KM3NeT are being installed at a depth of about 3500 m and 2500 m, respectively and their distance to the control stations is about 100 km and 40 km. The two detectors are optimised for the detection of cosmic neutrinos with energies above about 1 TeV (ARCA) and of atmospheric neutrinos with energies in the range 1 GeV– 1 TeV (ORCA). The expected maximum data rate is 200 Mbps per optical module. The implemented optical data transport system matches the layouts of the networks of electro-optical cables and junction boxes in the deep sea. For efficient use of the fibres in the system the technology of Dense Wavelength Division Multiplexing is applied. To comply with the scientific goals of KM3NeT, a time calibration of 1 ns between the many optical modules in the detector arrays is essential for the reconstruction of the neutrino events. For the first time in a deep sea neutrino telescope the White Rabbit protocol over Ethernet is used for the clock distribution. Downstream slow control and base module signals are broadcasted to all optical modules in the detector array. Synchronisation is achieved by communication between a White Rabbit master onshore and a White Rabbit slave unit inside the optical modules. In this contribution the KM3NeT broadcast optical data transport system is presented.

56 Gbps externally modulated widely tunable lasers with SOA boosters heterogeneously integrated on silicon

We demonstrate externally modulated widely tunable lasers co-integrated with semiconductor optical amplifiers (SOAs) heterogeneously integrated on silicon. The widely tunable laser enables continuous single-mode operation over a tuning range of approximately 40 nm, with a side-mode suppression ratio (SMSR) of at least 50 dB and an average waveguide-coupled optical power of 5 mW. The integrated electro-absorption modulator (EAM) exhibits an extinction ratio (ER) of 16 dB when reversed biased at -2 V. The bit-error-rate (BER) measurements conducted across the available optical bandwidth (15 nm) showcase error-free transmission at 32 Gbps using non-return-to-zero (NRZ) signals for the majority of wavelengths in a back-to-back (B2B) configuration. Additionally, transmission measurements over distances of up to 10 km through a standard single-mode fiber (SSMF) have been successfully demonstrated. Dynamic extinction ratio (DER) values exceeding 4.5 dB are achieved for all wavelengths. Open-eye diagrams were measured up to 56 Gbps. These results demonstrate that this compact mono-epitaxial externally modulated tunable laser with integrated optical amplification can be a cost-effective transmitter solution for dense wavelength division multiplexing (DWDM) metropolitan and access networks.

Performance analysis of a 400-Gbps DWDM-FSO system using advanced modulation formats and under adverse weather conditions

Free space optical (FSO) systems offer an attractive and cost-effective solution for providing communication services in remote regions, as they allow secure transmission without the need for licensing and with lower deployment costs. However, the performance of FSO systems can be significantly impacted by atmospheric turbulences, creating considerable challenges to their deployment. To meet the expanding bandwidth requirements in optical networks, dense wavelength division multiplexing (DWDM) has emerged as a viable option. The development of a 400-Gbps DWDM-FSO system with advanced modulation formats is the subject of this paper. To ensure efficient energy conservation in such a system, power consumption needs to be minimized while maintaining performance level; this calls for optimization of different components within the system. The system is made up of 10 channels and each channel can transmit data at 40 Gbps. Various modulation schemes like carrier-suppressed return-to-zero, modified duo binary return-to-zero, differential phase shift keying, and duo binary return-to-zero are studied for their impact on system performance parameters Q-factor and bit error rate (BER) in C-band around 1550 nm wavelengths. The assessment is also extended to the effects that changing FSO length, input power, and data rate have on these two parameters as well as an evaluation regarding how differing atmospheric conditions influence the FSO system’s effectiveness.

Real-time demonstration of 64 × 200 Gbps UDWDM-PON downstream transmission based on silicon photonic integrated transceiver

Coherent detection, high-order modulation, and dense wavelength division multiplexing (DWDM) technologies provide solutions for increasing bandwidth demand of future access networks. We experimentally demonstrate a real-time 64 × 200-Gb/s coherent ultra-dense wavelength-division (UDWDM) coherent passive optical networks (PONs) at 75-GHz channel spacing. The demonstrated downlink transmission is realized with the dual-polarization QPSK (DP-QPSK) modulation scheme. The cost is reduced by using silicon photonic integrated coherent transceiver modules and wider grid AWGs. The power budget is evaluated when all 200 channels are launched at C band. The power budget is 26 dB after 20-km G.652D standard single mode fiber (SSMF) transmission without amplifier at the receiver side under soft-decision FEC (SD-FEC) threshold of 1 × 10−2, and can achieve 32.5 dB with pre-amplified semiconductor optical amplifier (SOA) used at the receiver side.

MODELLING OF A TBPS SYSTEM FOR 5G WIRELESS COMMUNICATION UTILIZING DWDM RFoF

In recent times, several sectors and businesses have been doing extensive research on the usage of Dense Wavelength Division Multiplexing (DWDM) and Radio Frequency Over Fiber (RFOF). These two technologies are considered to be the most significant features. Increasing the data rate was a significant challenge that needed to be addressed, and the goal was to successfully implement a fiber optic system that was dependable and had a high number of associated channels. As a consequence of this, a 64-channel DWDM RFOF system that is capable of supporting a larger number of data rates of 2.56 Tbps has been designed and implemented in this study. A significant number of channels that have been sampled will be chosen for inquiry based on the characteristics of Quality Factor (QF) and Bit Error Rate (BER) that have been researched. This study will be carried out with the assistance of Optisystem software. These findings would be investigated at distances ranging from sixty to one hundred eighty kilometers, with the NRZ modulation format being used and a lunched power of zero decibels per meter. Additionally, the purpose of this study would be to explore the three distinct techniques of compensation, namely pre, post, and symmetrical, to quantify the individual performance of each approach on the suggested system. According to the findings, the use of symmetrical-based compensation yielded the most favorable outcomes, with the average QF produced falling within the range of (20.33-14.09) dBm over distances ranging from (60-180) kilometers. This demonstrates the dependability of the proposed system.

Development of a Technique for Mitigating Four-Wave Mixing Effect in Dense Wavelength Division Multiplexing System Using DP-QPSK with Channel Spacing

A Dense Wavelength Division Multiplexing (DWDM) system is a vital component in the optical network for the transmission of high data over a long distance. However, the non-linear effect of Four-Wave Mixing (FWM), one of the critical non-linear effects, limits the channel capacity and the amount of data that the DWDM system transmits. Intensity Modulation formats and Channel Shuffling algorithms being used to overcome the impact of FWM in DWDM are unable to sufficiently suppress the FWM effect due to limited capacity. This research, therefore, examined the mitigation of the FWM effect in the DWDM system using Dual Polarization Quadrature Phase Shift Keying (DP-QPSK) and channel arrangement. The DP-QPSK was designed and implemented using 100 GHz for both Equal Space Channel Allocation (ESCA) and Unequal Space Channel Allocation (USCA). It was analysed on a 64-channel DWDM system operating at 100 Gbps capacity over a transmission distance of 1000 km. The DP-QPSK-based ESCA and USCA techniques were simulated using OptiSystem 17 simulation software and Python for data analysis. The performance of the system was evaluated using bit error rate (BER), optical signal-to-noise ratio (OSNR) and Electrical Constellation Diagram. Validation was done with other advanced modulation formats: Quadrature Phase Shift Keying (QPSK) and Differential-Quadrature Phase Shift Keying (D-QPSK). The DWDM system using DP-QPSK gave better performance due to the highest OSNR and BER values obtained when compared with ESCA-based QPSK and D-QPSK techniques. The technique can be used to suppress the effect of FWM in optical communication systems.

Design and simulation of an enhanced optical demultiplexer using photonic crystal resonators

The purpose of this paper is to examine the design, simulation, and optimization of a demultiplexer optical system using photonic crystal resonators. Utilizing the distinct properties of photonic crystals, the proposed device achieves high-quality resonances, efficient wavelength separation, and minimal crosstalk. These characteristics are crucial for enhancing the performance of dense wavelength division multiplexing (DWDM) systems, which require precise and efficient channel separation to manage increasing data traffic. Extensive simulations conducted with the RSoft CAD tool explore the impact of varying resonator parameters such as refractive index, geometric dimensions, and material composition on the device's performance. The results indicate substantial improvements in transmission efficiency and quality factor, with average values of 98.675% and 3131.125, respectively. Furthermore, the ability to fine-tune these parameters allows for the customization of the demultiplexer to specific wavelength ranges, making it highly adaptable for various telecommunications applications. This research aims to propel the development of compact, high-performance photonic devices that meet the growing demands of modern communication networks, ultimately contributing to more efficient and reliable optical communication systems.

Intensity noise reduction in quantum dot comb laser by lower external carrier fluctuations.

This work investigates the impact of carrier noise induced by an external current source on the linewidth enhancement factor (LEF) and relative intensity noise (RIN) of a 100 GHz quantum dot fourth-order colliding-pulse mode-locked laser (MLL), driven by a normal pump with Gaussian-distributed carrier sequences and a quiet pump with sub-Poissonian-distributed carrier sequences. The results indicate that under a normal pump, the LEFs are approximately zero for reverse saturable absorber (SA) bias voltages ranging from 0 to 2.5 V, and the laser achieves a RIN as low as -156 dB/Hz. When using a quiet pump, both the LEF and RIN are reduced across all SA bias conditions, particularly at low reverse SA bias voltages. Specifically, the LEF decreases by up to 0.58 at 0 V, and the average RIN spectrum is reduced by more than 3 dB at the same voltage. This work provides a straightforward approach for the development and optimization of multi-channel light sources for dense wavelength division multiplexing (DWDM) technologies with low optical noise.

Design and theoretical analysis of broadband bend-resistant low-loss hollow-core anti-resonant fiber

With the development of modern fiber-optic communication technology, bend-resistant low-loss fiber within the S+C+L bands is essential to meeting the requirements of dense wavelength division multiplexing (DWDM) systems, and a small-tube-added multi-nested hollow-core anti-resonant fiber (SM-HC-ARF) is proposed. In conventional double-nested HC-ARF, a pair of circular tubes are tangent to both the inner and outer tubes to form a multi-nested structure. A small tube is put in the gap between the nested structure to enhance the anti-resonance effect further. The influence of fiber structural parameters on transmission characteristics is analyzed by the finite element method combined with the perfect matching layer condition. The numerical results show that, in the range of 1460–1625 nm, the bending loss and the confinement loss are less than 1.17 (at a bending radius of 8 cm) and 0.80 dB/km, respectively. Specifically, at 1550 nm, the bending loss is 0.43 dB/km, and the confinement loss is 0.33 dB/km. The broadband anti-bending low-loss SM-HC-ARF can be expected to apply in the DWDM system and other optical communication technologies.

Analysis of Ultra-Dense Wavelength Division Multiplexing (UDWDM) in a Passive Optical Network (PON)

Passive Optical Networks (PONs) are essential in optical communications to meet the increasing demand for network capacity and connected users, ensuring reliable and adaptable connections for data transmissions. These networks also simplify infrastructures and efficiently utilize energy by eliminating the need for active devices. In this context, Ultra- Dense Wavelength Division Multiplexing (UDWDM) is one of the most prominent solutions for data transmission. This technology uses the narrow separation between channels from 25GHz and even as small as 6.25GHz to increase the transmission capacity. This document analyzes the performance of UDWDM considering the transmission of three simultaneous channels in a PON network for which three different scenarios have been considered for the analysis with the following parameters: i) transmission speed from 10 Gbps to 17 Gbps, ii) the distance from 10 km to 20 km and iii) the separation between channels of 15GHz, 20GHz, and 25GHz. The performance metrics for the analyzed scenario are the bit error rate and the eye diagram. To ensure the reception of the transmitted channel, an analysis of raised cosine and Gauss filters is also discussed. Including these filters allows for verifying whether their use enhances the performance of the channels compared to transmission without a filter. This is crucial for understanding how filters can optimize the quality and reliability of data transmission in a PON, which is of great importance in environments where high efficiency and connection quality are required.

Enabling IP-optical integration in core and metro networks [Invited

IP-optical (Internet protocol and optical) integration, or “IP over DWDM (dense wavelength division multiplexing),” is a concept spanning over two decades since the advent of coherent DSP (digital signal processing). In recent years, coherent DSP technology has progressed to a point where it can be integrated on small pluggable form factors that can be equipped in optical line systems and disaggregated transponders or directly in IP routers to support a range of metro and core applications. The option of equipping pluggable digital coherent optics (DCOs) directly in IP routers has the biggest potential for operational cost savings but hinges on the availability of a unified management environment with a single pane of glass to coordinate and automate IP routing and optical transport functions. This work presents alternative software-defined networking (SDN) architectures and evaluates the challenges associated with the evolution to IP over DWDM network architectures. It demonstrates the first, to our knowledge, implementation of the Transport API supporting colored pluggable interfaces in routers in a real network testbed. This work contributes to the realization of end-to-end network management for IP-optical networks, offering operators comprehensive visibility into multi-layer and multi-domain services and empowering revenue generation.

Optimization of underwater visible light communication transmission using multilevel regression modelling

This paper proposes the 32-Channel Dense wavelength Division Multiplexing (DWDM) system for Underwater Visible Light Communication (UVLC). The proposed DWDM-UVLC system performs the transmission of visible light data under different underwater ocean environmental conditions such as Pure sea, Clear ocean, and Coastal ocean water and ocean pollution such as oil spills, microplastics. The data transmission through visible light in underwater ocean environment is a challenging task due to attenuation in ocean water, which causes variations in water column parameters such as temperature, Ph, salinity, and chemical oil spill contents in water such as water with oil spills, and microplastics. The proposed dense wavelength Division Multiplexing (DWDM) system for Underwater Visible Light Communication (UVLC) is optimized using Bayesian optimized Multiple Regression Learning (BO-MRL) method. The BO-MRL based DWDM for UVLC mitigates the attenuation problems in data transmission, which is in the range of approximately 350m. The proposed DWDM-UVLC system is evaluated through the Performance metrics such as Q-factor, Minimal BER and proper spectral eye characteristics. The proposed BO-MRL based DWDM consists of non-return-to-zero (NRZ) modulation, which performs better in 320 Gbps, transmission in the range of 200m and 350m, and achieves the maximum Q-factor of 19.2364 with a minimal BER of 9.16489 e−083.

Stable and wavelength-tunable multiwavelength laser for high-rate measurement device independent quantum key distribution

Measurement device independent quantum key distribution (MDI QKD) has attracted growing attention for its immunity to attacks at the measurement unit, but its unique structure limits the secret key rate. Utilizing the wavelength division multiplexing (WDM) technique and reducing error rates are effective strategies for enhancing the secret key rate. Reducing error rates often requires active feedback control of wavelengths using precise external references. However, for a multiwavelength laser, employing multiple references to stabilize each wavelength output places stringent demands on these references and significantly increases system complexity. Here, we demonstrate a stable, wavelength-tunable multiwavelength laser with an output wavelength ranging from 1270 to 1610 nm. Through precise temperature control and stable drive current, we passively lock the laser wavelength, achieving remarkable wavelength stability. This significantly reduce the error rate, leading to an almost doubling of the secret key rate compared to previous experiments. Furthermore, the exceptional wavelength stability offered by our multiwavelength laser, combined with the WDM technique, has further boosted the secret key rate of MDI QKD. With a wide wavelength tuning range of 5.1 nm, our multiwavelength laser facilitates flexible operation across multiple dense wavelength division multiplexing channels. Coupled with high wavelength stability and multiple wavelength outputs simultaneously, this laser offers a promising solution for a high-rate MDI QKD system.

Multipoint temperature measurement system composed of fiber-optic Fabry–Perot interference sensors and a wavelength-division multiplexing filter

A multipoint optical-fiber remote temperature measurement system was developed using reflection-type sensors consisting of a Fabry–Perot interference (FPI) structure with good temperature characteristics combined with a wavelength-division multiplexing (WDM) filter. The FPI sensor was fabricated using a short temperature-sensing region sandwiched between single-mode fibers. FPI optical fibers and a WDM filter functioned as the temperature sensors and wavelength-selective optical source using an amplified spontaneous emission light source, respectively. This system was operated in a dense WDM configuration using an arrayed waveguide wavelength filter.

Dense Wavelength Division Multiplexing (DWDM) in IT Networks: A Leap Beyond Synchronous Digital Hierarchy (SDH)

The evolution of telecommunications has seen significant milestones, notably the shift from Synchronous Digital Hierarchy (SDH) to Dense Wavelength Division Multiplexing (DWDM). This transition marks a pivotal advancement in the performance of Information Technology (IT) networks, offering unparalleled improvements in bandwidth, scalability, and efficiency. DWDM technology enables the simultaneous transmission of multiple data streams across a single optical fiber by using different wavelengths of light, significantly enhancing data throughput and network capacity. This article delves into the technical foundations of DWDM, compares its performance enhancements over SDH systems, and explores its impact on modern IT network infrastructure.

Simulating Free-Space Optical Communications to Support a Li-Fi Access Network in a Smart City Concept

Smart city development has grown rapidly in the decades since 4G and 5G technologies have been released. Moreover, a highly reliable network is required to support the Internet of Things (IoT) and mobile access within a city. Light Fidelity (Li-Fi) technology can provide huge bitrate transmission and high-speed communications. In the research, a backbone based on Free-Space Optical (FSO) communication (FSO) is designed through simulation to provide a Li-Fi access network with a high capacity data rate. The originality of the proposed method is the implementation of double filtering techniques, which gives an advantage when forwarding the signal to a node and improves the quality of the signal received by the Li-Fi. The FSO as the Optical Relaying Network (ORN) is designed with a configuration of 12 channels of Dense Wavelength Division Multiplexing (DWDM) amplified by optical amplifiers in the transmitter and receiver. The signal output is filtered by a Fiber Bragg Grating (FBG) and a Gaussian filter. In the simulation, the ORN has node spacing in the range of 500 m to 2,000 m. Then, the data transmission rate at 120 Gbps is provided by the implementation of DWDM channels to serve as an access network. From the simulation, the FSO backbone can optimally deliver highly reliable Li-Fi access networks. When the nodes are spaced in a 500–2,000 m range, the Bit-Error-Rate (BER) performance is produced at the order of 10−6.

Metallic layered VSe2 saturable absorber based single- and dual-wavelength ultrafast fiber laser

Vanadium selenide (VSe2) is a special two-dimensional (2D) transition metal dichalcogenide (TMD) material with metallic properties similar to graphene, which has been proved to have saturable absorption properties and used in mode-locked fiber lasers. As an excellent saturable absorber (SA) material, VSe2 has advantage of ultrafast carrier recovery time and broadband optical response range. However, the potential application of VSe2 in the field of ultrafast photonics has not been fully developed so far. In this work, the as-prepared VSe2 nanosheets were deposited on tapered fiber by optical deposition to obtain VSe2 SA. By inserting VSe2 SA into an Er-doped fiber laser, the mode-locked pulses with a central wavelength of 1574.4 nm can be obtained. The pulse width of the laser is measured to be ∼680 fs which is narrowest in the reported VSe2 SA-based lasers. In addition, the unique dual-wavelength mode-locked pulse is also obtained by further adjusting intracavity dispersion and polarization. This kind of dual-wavelength pulse is valuable in high order harmonic generation enhancement, terahertz wave generation, dense wavelength division multiplexing, dual-frequency comb and other applications. Our results show that metallic VSe2 is of great potential value in ultrafast fiber laser.

Optimizing High Data Rate Up to 2.5 Tbps Transmission using 64-Channel DWDM System with DCF and NRZ Modulation

Objectives: This study aims to enhance and optimize a modern communication system for high data rate transmission using Dense Wavelength Division Multiplexing (DWDM). The objectives include employing a 64-channel DWDM system, implementing different data speeds, and utilizing a dispersion compensation method. Methods: To achieve the objectives, we simulate and analyze the effects of Dispersion Compensation Fiber (DCF) in a DWDM system with 64 channels. The system employs Non-Return-to-Zero (NRZ) modulation format at varied bit rates and multiple energy levels. We propose a method for achieving data rates of 10 to 40 Gbps using NRZ modulation and Erbium-Doped Fiber Amplifier (EDFA) over a single-mode fiber transmission distance of 40 to 160 km, along with a dispersion compensation fiber of 8 to 32 km (DCF). The performance of the developed model is evaluated based on Quality Factor, Bit Error Rate (BER), Eye Height, and Threshold. These metrics are measured at two input energy levels from an optical power source, covering a communication capacity ranging from 0.625 Tbps to 2.5 Tbps. Findings: Through the simulations and analyses, we uncover the impact of dispersion and demonstrate the effectiveness of the proposed method in compensating for dispersion effects. Performance analysis of two different input transmitter power levels, -10 dBm is more efficient compared to 0 dBm input transmitter power in terms of bit error rate and quality factor. Novelty: This study presents a novel approach to improving modern communication systems by utilizing DWDM with a dispersion compensation method. The use of a 64-channel DWDM system, combined with the proposed NRZ modulation technique and dispersion compensation fiber, provides an efficient solution for achieving high data rates over long transmission distances while minimizing the effects of dispersion. The findings contribute to the advancement of communication systems for high data rate transmission. Keywords Dispersion effect, Bit Error Rate, Q-factor, Optisystem software, Erbium doped fiber amplifier

Analysis the flat gain/noise figure using RAMAN-Reflective Semiconductor Hybrid Optical Amplifier in C + L + U triple band for super dense wavelength division multiplexing system

Abstract Nonlinearity, flat gain and noise figure are the prime concern for super dense wavelength division multiplexing (SD-WDM) systems which have been resolved from RAMAN-RSOA hybrid optical amplifier (HOA) for the first time in this paper. Channel capacity is taken up to 400 with data rate of 10 Gbps. Performances are evaluated with respect to C + L + U band for 1520–1680 nm and 1520 to 1640 nm. RSOA is operated at 40–120 mA bias current to attain best rating flat gain of 34.07 dB with variation of 3.5 dB than the others HOAs (RAMAN-EDFA, RAMAN-SOA and EDFA-SOA). Moreover, the impact of EDFA-SOA is not acceptable in terms of noise figure for SD-WDM optical communication system.