Showing papers in "Journal of optical communications in 2021"

Simulative and analytical methods of bidirectional EDFA amplifiers in optical communication links in the optimum case

Abstract: This study has demonstrated the simulative and analytical methods of bidirectional EDFA amplifiers in optical communication links in the optimum case. The output power, max. Q factor and light signal/noise ratio variations are clarified with pump power variations at the bidirectional amplification EDFA amplifier for the previous/proposed models at optimum EDFA length of 8 m. As well as the output power and max. Q factor variations with EDFA amplifier length variations are demonstrated at the bidirectional amplification EDFA amplifier for the previous/proposed models at various pump power levels. The optimum operation efficiency case is observed at 8 m EDFA amplifier length and 120 mW pumping power.

Fiber optic propagation problems and signal bandwidth measurements under high temperature and high dopant germanium ratios

Abstract: This study presents fiber optic losses/dispersion and signals bandwidth measurements under high temperature and high dopant germanium ratios variations for ultra-long haul distances without amplification stage. The fiber losses, fiber dispersion, and total fiber data rates are estimated and compared with the previous results under room temperature and high germanium dopant ratios to silica glass fiber. Then the model is extended for ultra-fiber transmission distances up to 500 km under high-temperature variations without using any amplification stage. The fiber losses/dispersion coefficient is degraded, and the total fiber data rates are enhanced with the increment of high dopant ratios of germanium.

Cascaded stages of parametric optical fiber amplifiers with Raman fiber amplifiers for upgrading of telecommunication networks through optical wireless communication channel

Abstract: This paper contains a main model which concludes a two optical fiber cable along 70 km and with Parametric/Raman amplifiers with a result of total power 0.781 dBm that computed by the optical power meter which is located before the receiver part and the second optical fiber channel, a total power −44.186 dBm at the end of model which is computed by the electrical power meter visualizer, and a max. Q factor 2.548 computed by the BER analyzer. The suggested model has outlined some updates on the previous model to improve the results so that the results are increased at the same length as the following: total power of optical signal becomes 10.039 dBm, total power of electrical signal becomes 0.624 dBm, and the max. Q factor becomes 9.60787.

Simulative study on the cascaded stages of traveling wave semiconductor optical amplifiers based multiplexing schemes for fiber optic systems improvement

Abstract: This study has outlined the performance analysis of the cascade traveling-wave optical amplifier (Semiconductor optical amplifier [SOA]) with multiplexing techniques based on fiber communication transceiver systems. The maximum Quality factor is measured against signal power. Signal input power level is enhanced by using the suggested model with previous model. The low pass Bessel filter removes the unwanted ripples from the original signal. The suggested model has clarified better performance efficiency than the previous model.

Gain/noise figure spectra of average power model Raman optical amplifiers in coarse wavelength multiplexed systems

Abstract: This work clarifies the gain/noise figure spectra of average power model Raman optical amplifiers in coarse wavelength multiplexed systems. The proposed model have a total received power of 16.306 dBm, signal gain of 21.68 dB, and noise figure of 3.802 dB at the same operation parameters of the previous model which operated at length 0.2 km at the optical fiber coarse wavelength division multiplexing (CWDM) and transmitted signal power is 20 dBm. So the updates help us to greatly improve the system.

The effects of Tx./Rx. pointing errors on the performance efficiency of local area optical wireless communication networks

Abstract: This study presents the effects of Tx./Rx. pointing errors on the performance efficiency of local area optical wireless communication networks. The received signal power and max Q factor are measured in the presence of vertical-cavity surface-emitting lasers (VCSELs) bias current and modulation current at maximum propagation distance for the wireless network. The signal is enhanced with increasing of bias and modulation peak currents of the VCSEL device. The optimum received power and max. Q factor is also examined at Tx./Rx. the pointing error of 0.1 mrad and propagation reach of 5 km at available bit rates transmission of 10 Gb/s.

High-speed fiber system capacity with bidirectional Er-Yb CDFs based on differential phase shift keying (DPSK) modulation technique

Abstract: This paper simulates the bidirectional Er-Yb codoped fiber amplifiers (CDFs)-based DPSK modulation scheme for high speed fiber system capacity. The combination of Erbium-Ytterbium codoped fibers into a single fiber has been developed for the extension of the absorption bands for doped fibers. The signal gain variations versus pump wavelength variations have been demonstrated for various doped amplifiers with the proposed Er-Yb CDFs at amplifier length of 5 m. Also the signal gain variations versus pump wavelength variations have been illustrated for the proposed Er-Yb CDFs at 5 m amplifier length in different pumping configurations. The total optical power, max. Q factor, total electrical power, output optical signal/noise ratio, and signal gain variations versus fiber length variations have between simulated and clarified in the presence of bidirectional various lengths of Er-Yb CDFs.

In line and post erbium-doped fiber amplifiers with ideal dispersion compensation fiber Bragg grating for upgrading optical access networks

Abstract: This model in line and post erbium-doped fiber amplifiers with ideal dispersion compensation FBG for upgrading optical access networks for an extended distance of 60 km inside the optical fiber cable with a bit rate 10 Gb/s and Erbium-doped fiber amplifier (EDFA) which applied at length 5 m. The electrical results are measured by electrical visualizer (eye diagram analyzer, electrical power meter visualizer). The eye diagram analyzer used to calculate the min bit error rate in addition to the maximum Q factor which has a result in the proposed model is 51.97. The electrical power meter visualizer used in the proposed model to calculate the total power which has a result of 23.70 dBm.

Chirped Gaussian pulse propagation with various data rates transmission in the presence of group velocity dispersion (GVD)

Abstract: Linear/Measured chirped Gaussian pulse propagation is simulated at various data rates transmission in the presence of group velocity dispersion without amplification unit. The power variations (PVs) vs. frequency, time period are also clarified after 250 km fiber channel length and 10 Gb/s bit rate (BR) of for Gaussian pulse generators with linear chirp factor of 2 rad/s, measured chirp factor (alpha parameter of 2 rad/W, Adiabatic chirp of 10 s−1). Moreover the overall total light power after fiber, the overall total electrical power after APD receiver are studied and clarified for Gaussian pulse generators with linear chirp, measured chirp factor. PVs vs. frequency, time period are simulated after APD receiver for Gaussian pulse generators with linear chirp, measured chirp factor. Maximum signal amplitude variations vs. time after APD receiver for Gaussian pulse generators with linear chirp, measured chirp factor are also clarified with the numerical simulation results.

Low Input Power an All Optical 4 × 2 Encoder based on Triangular Lattice Shape Photonic Crystal

Abstract: Abstract An all optical encoder based triangular lattice shape photonic crystal (PC) is proposed. The device is composed of two ring resonator waveguides and two OR gate with four input ports waveguides and two output ports waveguides in triangular lattice shape PC. The band diagram of base PC structure calculated by plane wave expansion (PWE) method. Also, transmission and distribution of electrical field behaviors of the proposed device are verified by two dimensional finite difference time domain (2D-FDTD) method. The proposed 4 × 2 encoder can operate at third communication window range, considering definitions of logic 0 and 1 being the normalized transmission as less than 3% and greater than 95% respectively. Despite the nonlinear encoders, in our case, due to the non-use of non-linear effects such as Kerr effect, low input power required for encoder.

Effect of Multiwalled Carbon Nanotube Reinforcement on the Opto-Electronic Properties of Polyaniline/c-Si Heterojunction

Abstract: Abstract In this paper synthesis and extensive investigation of the microstructural and optoelectronic properties of polyaniline (PANI), Multiwalled carbon nanotube (MWCNTs) and MWCNTs reinforced PANI composites is presented. MWCNTs- PANI composites have been deposited by spin coating on silicon wafer substrate. Fourier Transform Infrared Spectroscopy shows no difference between PANI and its composites. However a change in peaks shape and absorption intensity has been observed. A strong effect of the MWCNTs weight percentage on the PANI/MWCNTs composites has been demonstrated. It was find that the thermal stability improved with increasing MWCNTs content. The optical band gap of the PANI thin films has been effectively tuned from 2.38 to 1.78 eV as the MWCNTs content increases from 5 to 15 wt.% The Current–voltage (I–V) characteristics of the fabricated devices shows a significant improvement in current with MWCNTs weight percentage content. It was observed a strong enhancement of composite in the conductivity as well as in the current level. The microscopic images show that the dispersion of MWCNTs into PANI leads to the formation a new conductive pathway.

Design and simulation of an all optical 8 to 3 binary encoder based on optimized photonic crystal OR gates

Abstract: Abstract The most recently developed optical encoders are based on non-linear Kerr effect which require high input power. Here, we report 8 to 3 optical binary encoder based on linear effects which greatly reduces the input power requirement. The proposed encoder consists of three optical 4-input port OR gates and an optical buffer gate. Simulation results have proved correct operation states of the encoder and numerical analysis is done in order to additional evaluation. The maximum switching delay and total footprint of proposed structure are about 160 fs and 1418 µm2, respectively.

Review of LiFi Technology and Its Future Applications

Abstract: Abstract In order to respond to the increasing demand of capacity and bandwidth caused by the high number of wireless applications and users, LiFi technology was introduced. It uses the visible light spectrum instead of the radio spectrum to transmit data wirelessly through the illumination of LED lamps. The main advantage of this technology is to provide wireless communications with high data rates. Other advantages include efficiency, availability, security and safety. Also, this technology uses free unlicensed spectrum, and it is cost-effective. Additionally, unlike RF systems, no multipath fading and the transmitter and receiver circuits are not complex. However, LiFi has several issues, which include high path loss, sensitivity to blockages and Non-line-of-sight (NLOS) situations. Probably, the biggest issue of LiFi is the uplink communication which is difficult to implement due to practical and cost reasons. Several future applications of this technology include places where RF is restricted such as hospitals and airplanes. Also, it can be used for traffic management, underwater communication, and outdoor access to the Internet. Moreover, it can be combined with WiFi technology either in hybrid technique or aggregated technique. It is found that later technique gives better results. Another possible application is the optical attocells. It is found that the hexagonal cells model is the best for deterministic deployments of optical APs, whereas the hard-core point process (HCPP) model is the best for random deployments. Furthermore, LiFi can be used for multiuser access with high data rate by using non-orthogonal multiple access (NOMA) technique. Due to the great features of LiFi, more applications and everyday life devices will adopt this technology in the future. However, Because of its limitations, it may not totally replace RF technology, but they will work collaboratively to achieve a better performance.

Identification of a Malicious Optical Edge Device in the SDN-Based Optical Fog/Cloud Computing Network

Abstract: Abstract Software-defined networking (SDN) and optical transmission are the most cost-effective technologies for implementing high-bandwidth-based communication in the fog/cloud computing environment. The passive optical network uses optical line terminals and optical network units as optical edge devices (OEDs) to deliver fog/cloud-based services effectively. The security of such OEDs is one of the key issues for successful implementation of fog/cloud computing over the SDN-based optical network. The main security challenge is to detect and prevent the malicious OED that transmitting abusing data-frames in the SDN-based optical fog/cloud computing network. An OED can be easily hacked by the attacker to launch intrusive attacks those affect the quality of service of the optical channel. In this paper, a secure framework is proposed for identifying malicious OED in the fog/cloud computing over the SDN-based optical network. It identifies the malicious OED and shifts it to the honeypot to mitigate and analyze the attack. It uses two-stage hidden Markov model (HMM), intrusion detection system (IDS)-based fog manager and an optical virtual honeypot device (OVHD). A two-stage HMM is effectively used to reduce the false alarms of IDS in the identification of malicious OED and shifting it onto the OVHD. The OVHD is created in the SDN-based optical network by using the concept of free-available-resource and optical network virtualization. The proposed OVHD logs all malicious activities as well as attacker’s path for preventing future attacks. In order to validate the proposed framework, the simulation of two-stage HMM is implemented in MATLAB and mitigation impacts of the internal attacks are studied by using iFogSim toolkit. The results show the effectiveness of the proposed framework.

Minimization of Nonlinear Impairments and Its Impact on Transmission Performances of High-Capacity Long-Haul Optical Networks

Abstract: Abstract High-capacity and long-haul transmission gained great significance in modern communication networks. Optical fiber communication system is good enough to face the high demand of current telecom terrific. This paper will propound the theoretical model showing nonlinear factors which degrade the transmission performances of high-capacity long-haul network. The postulatory model will be validated using simulation of key nonlinear factors such as effective area, launch power, refractive index and fiber length. The transmission performance of the high-capacity long-haul optical network would be analyzed on the basis of some key parameters such as bit error rate and signal-to-noise ratio. Mitigation of nonlinear impairments shows significant impact on transmission performances of high-capacity long-haul optical networks.

Multi-Beam Free-Space Optical Link to Mitigation of Rain Attenuation

Abstract: Abstract Free-Space optical (FSO) link is an optical communication technology that uses light or laser as the carrier diffuses into free space to transfer data information between the transmitter and the receiver through the air channel. In this paper, a dual transmitters and receivers with multi-beam technique were designed to Study the effects of rain attenuation on the system to be used through FSO during the rainy weather. FSO model system was designed and simulated using OptiSystem7.0 software. The results analysis of FSO link within (1.6 - 3.9 km) ranges according to a Charbonneau model for rain attenuation. The transmitting data with NRZ modulation was designed and analysis of the performance System efficiency parameters such as bit error rate (BER) and Q. Factor for different optical links. The results of the simulation showed that the received signal power decreases and the bit error rate is increasing when the rain rate is increasing.

A Proposal for All Optical XNOR Gate Using Photonic Crystal Based Nonlinear Cavities

Abstract: Abstract All optical logic gates can play very important roles in all optical digital systems. In this paper we designed an all optical XNOR gate. The switching part of the designed XNOR consists of two nonlinear resonant cavities. The nonlinear cavities were created by adding two nonlinear defects made of doped glass. Plane wave expansion and finite difference time domain methods were used for simulating the designed structure. The final structure has two input and one output ports. The output port is ON when the input ports have similar states. For the designed structure the delay time is about 2.5 ps.