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Dispersion-Shifted Fiber (DSF) is essential for reducing chromatic dispersion in high-speed optical communication systems. This study investigates the influence of Four Wave Mixing (FWM) on the quality of signals in orthogonal channels. We examine the advantages of DSF technology and analyze the impact of modulation formats such as On-Off Keying with Return-to-Zero (OOK-RZ) and Duo Binary Modulation class-1 (DBM-1) on transmission performance at different distances. This research assesses the efficacy of orthogonal channels in mitigating four-wave mixing (FWM) effects and improving the overall performance of eight-channel systems at distances of 100 km and 200 km through computer simulations. The results of our study show notable enhancements, namely in optimizing the Q-factor (a metric for signal quality) and reducing bit error rates when employing orthogonal channels compared to previous work. By integrating orthogonal channels with OOK-RZ modulation, we achieved higher performance and reduced nonlinear impairments in a simulated eight-channel system with 50 GHz spacing and 80 Gb/s data rates. This effect was particularly pronounced at high input power levels. At an input power of 20 dBm and a distance of 200 km, this particular combination yielded a maximum Q-factor of 27.25 and a minimum FWM power of −54 dBm. In comparison, under the same conditions, the use of OOK-RZ alone resulted in an FWM power of −24 dBm and a Q-factor of only 1.63. This research provides vital insights into enhancing the efficiency and dependability of optical communication systems, hence facilitating breakthroughs in high-speed data transfer and network scalability. • FWM crosstalk is greatly influenced by modulation quality, channel orthogonality, and dispersion conditions. • A new approach involving the combined utilization of orthogonal dense channels with OOK-RZ modulation has demonstrated superior system performance and minimized nonlinear defects, • New technique showcases improved efficiency and reliability in data transmission, offering potential advancements in various applications where signal integrity and robustness are paramount. • A technique for suppressing Four-Wave Mixing (FWM) crosstalk has been successfully implemented at dispersion values close to zero, with high pumping power, and dense channel spacing. • Interference is reduced under extreme conditions such as dense channel spacing, high pump power and low dispersion condition. [ABSTRACT FROM AUTHOR]

This study introduces a novel 9-core, 4-mode fiber characterized by its bend resistance and minimal crosstalk. Utilizing a hetero-core scheme, the cores are effectively isolated through trenches and air holes, significantly reducing inter-core crosstalk. The cores are strategically arranged in a square array to facilitate easier splicing. Through comprehensive simulation calculations, it is demonstrated that four LP modes can be consistently transmitted within the C+L band. The effective refractive index difference between adjacent modes exceeds 10−3, ensuring negligible intra-core crosstalk. Concurrently, the inter-core crosstalk of the LP02 mode is maintained below − 40 dB/100 km. The fiber's bending radius can be minimized to 60 mm without compromising performance, with the corresponding bending loss for the LP02 mode in the two outer cores measured at 1.6 × 10−5 dB/m and 3.95 × 10−6 dB/m, respectively. Each of the nine cores exhibits an effective mode area exceeding 95 µm2, and the fiber's relative core multiplexing factor at 1550 nm is 27.62. The proposed fiber's superior performance positions it as a promising solution for practical applications in optical fiber communication networks, potentially addressing the burgeoning capacity crisis in communication systems. [ABSTRACT FROM AUTHOR]

Polarization division multiplexing coherent optical OFDM (PDM-CO-OFDM) is an approach which ensures reaching high data rates by enabling the utilization of the amplitude, phase and polarization of light at the same time in long-haul transmissions. The channel equalizer is used for the compensation of the linear and nonlinear effects of fiber in the optical receiver, and channel estimation is realized with periodic training symbols. In this study, a channel equalizer based on modified Huber independent component analysis (MHICA) without training symbols (TS) was proposed for the PDM-CO-OFDM systems. Thus, the mathematical model of the PDM-CO-OFDM system and MHICA were analyzed. It is shown in the simulations that the proposed channel equalizer in the receiver can compensate for the linear and nonlinear effects in the optical channel and successfully recover the OFDM signals. In addition, compared to other ICA-based channel equalizers, the proposed channel equalizer is the fastest, and provides slightly improved or similar performance for QPSK and 16-QAM modulated signals respectively. Under the same conditions, the proposed channel equalizer achieves better performance than conventional TS-based frequency domain channel equalizers, both with and without intersymbol frequency-domain averaging (ISFA). [ABSTRACT FROM AUTHOR]

The key objective of this research paper is to design a type-II nano-heterostructure which could emit the radiations of the wavelength ˜1.55 μm. Here, we have proposed and designed a novel type-II "W" shaped InAlAs/InGaAs/GaAsSb nanoscale heterostructure and simulated its optical gain characteristics theoretically with the help k.p method by solving a 6 × 6 Luttinger-Kohn Hamiltonian for determining the carrier's localities within the heterostructure. The other calculations have been performed to determine the dispersion of carrier's energies, dipole transition elements and the optical gain characteristics. Finally, the simulated results clarified that the designed heterostructure is competent to emit the radiations of ˜1.55 μm wavelength (wavelength of near infrared region) and can be utilized in optical fiber communication systems. [ABSTRACT FROM AUTHOR]

Abstract We investigate the Kaup-Newell equation that represents one of the forms of derivative nonlinear Schrödinger equation. The model applies to the description of sub-pico-second pulse propagation through an optical fiber. A special complex envelope traveling-wave method is applied to find a nonlinear equation with a fifth-degree nonlinear term describing the dynamics of field amplitude in the nonlinear media. It is shown that the phase associated to the obtained pulses has a nontrivial form and possesses two intensity dependent chirping terms in addition to the simplest linear contribution. A class of soliton solutions of the bright, dark and singular type are derived for the first time. The requirements concerning the optical material parameters for the existence of these chirped structures are also discussed. [ABSTRACT FROM AUTHOR]

Abstract Soft curvature sensors have huge demand in the emerging field of soft robots, rehabilitative robots and morphing flight vehicles. However, the current soft sensors have limitations in sensitivity, repeatability, and fabrication cost, which hinder their practical applications. To address these issues, we propose a soft curvature sensor with soft silicone-polyvinyl chloride mixed substrate and fiber Bragg gratings (FBGs). The major contribution is obtaining a soft curvature sensor with extraordinary high sensitivity and repeatability. Using the pure bending model, the nonlinear relationship between the bending curvature and Bragg wavelength shift is analyzed. The reflection spectrums of the FBGs in the mixed substrate are measured, and the effect of the horizontal position and embedded depth of the FBG is analyzed experimentally. The optimal embedded position of the FBG and the sensitivity and repeatability of the soft curvature sensor is obtained. The results proved that the proposed sensor is soft enough to follow the contour of the object for real time measurement, the maximum sensitivity is up to 328.67pm/m−1 in the measurement range of 0m−1∼15m−1, and the fluctuation coefficient of repeated measurement is less than 0.07. The sensor is simple in structure, easy to fabricate and low cost. All these make it to be a promising approach for practical applications in the industrial and medical field. [ABSTRACT FROM AUTHOR]

Abstract In this work, a high capacity mode division multiplexing (MDM) based Inter-Satellite Optical Wireless system is presented. In order to increase capacity of the system, 64 linearly polarized modes are incorporated in the system. The proposed MDM Inter-Satellite Optical Wireless Communication system has been designed using various modulation techniques such as Manchester, DPSK and DQPSK at the different distances of 750–3750 km and data rates of 10, 20 and 40 Gbps. Results have been compared on the basis of Eye Diagrams, Q-factor as well as minimum Bit Error rate. The comparative analysis shows at the bit rate of 10 Gbps, DQPSK modulation technique provides highest Quality factor of 32.01 followed by DPSK and Manchester Modulation. DQPSK Modulation technique shows best performance till 40 Gbps and Manchester shows least. It is also observed that on increasing bit rates from 10 Gbps to 40 Gbps, Quality factor degrades. Proposed MDM IS-OWC system is reliable to use, flexible, cost effective and useful for long distance communication. [ABSTRACT FROM AUTHOR]

Abstract We propose a phase noise suppression scheme for RF signal remote fiber transmission based on a photonic phase shifter. Phase noise induced by the temperature variation and mechanical perturbation is suppressed automatically and effectively through a feedback network. The experimental results implement a full 360° phase shift using a microwave signal frequency 6 GHz over 30 km single-mode fiber with the system achieving a better stability performance. [ABSTRACT FROM AUTHOR]

Abstract We investigate and experimentally demonstrate the impact of continuous wave (CW) injection from a malicious ONU on the upstream transmission in a power splitting-based PON. Both OOK signal as used in a TDM-PON and OFDM signal in an OFDM-PON are considered. In our experiment, 10-Gb/s NRZ-PRBS and OFDM signals were used to test the effect of CW injection in TDM-PON and OFDM-PON, respectively. A bit error rate floor is observed for the upstream OOK signal when the signal-to-crosstalk ratio is reduced to 7.7 dB. Similarly, the CW injection from a malicious ONU also impose severe power penalty to the upstream OFDM signal. To overcome this security issue, we propose a novel protection scheme via harvesting the optical energy at the remote node (RN) that is originally wasted in a common power splitting-based PON. The proposed protection scheme can maintain the passive nature of the RN. [ABSTRACT FROM AUTHOR]

In this paper, we derived new explicit complex hyperbolic and complex trigonometric function solutions, especially dark, bright, combined dark–bright, singular, combined singular soliton and other soliton solutions from the conformable fractional Biswas–Milovic equation with Kerr law and Parabolic law nonlinearity that describes the long-distance optical communications and optical fibres for the solitons propagation. The reported results might play an important role in a nonlinear medium for explaining the physical meaning of the studied model. Therefore, it is also shown that the applied method provides a more powerful mathematical tool for investigating exact solitary wave solutions for many other nonlinear evolution equations in nonlinear medium. [ABSTRACT FROM AUTHOR]

In this study, InP/AlGaInAs/delta-InGaAs single quantum well for fiber-optic communications is presented, proposed and compared to the free delta layer even structure. The Al and Ga content and the thickness layers are self-consistently optimized using genetic algorithm. It is found that the optimization of structure confirm an improvement in the electron and hole wave function overlap, which leads to a significant enhancement in TE-polarized optical gain at room temperature. In addition, the transparency carrier density is significantly reduced by the insertion of delta-InGaAs thin layer which can be a necessity for fiber-optic communications. [ABSTRACT FROM AUTHOR]

A new circular photonic crystal fiber (C-PCF) with square air -holes in the cladding is proposed, which can support much more orbital angular momentum (OAM) modes. To optimize the design, the dependence of the number of OAM modes on fiber structure parameters is investigated. The simulation results show that the designed C-PCF can support 46 OAM modes stably over 800 nm bandwidth from 1.2 μm to 2.0 μm. Furthermore, the proposed C-PCF exhibits excellent fiber features, such as large effective index differences (˃10 −4 ) without doping, low confinement loss (lower than 10 −9  dB/m), relatively flat dispersion and small nonlinear coefficient (less than 2.58 km −1  W −1 ) for all eigenmodes. The proposed C-PCF could be a well-promising OAM fiber for mode division multiplexing(MDM) in high capacity fiber communication systems. [ABSTRACT FROM AUTHOR]

For the problems of light source fluctuation noises, zero drift and other problems of H 2 S gas concentration sensor in optic-fiber evanescent-wave absorption spectroscopy, double-light-path absorption system was designed to theoretically analyze the relationship between evanescent-wave power and gas concentration as well as detection sensitivity. Moreover, the relationship between evanescent-wave power and optical-fiber residual diameter in the optic fiber corrosion process was also studied. The sensing probes with different evanescent-wave power ratios were used to detect experiments of H2S gas concentration. The experimental results show that the sensitivity is up to 0.169 μw/ppm when the evanescent-wave power ratio of sensing probe is 10%, detected minimum H 2 S gas concentration is 5.1 ppm, the detection repeatability is good and the response time is only 2.03s. Due to low production cost, high sensitivity and short response time, the optic-fiber evanescent-wave sensor can be used for real-time on-line measurement of H 2 S gas in the area of the hydrocarbon exploration and development. [ABSTRACT FROM AUTHOR]

Finite Difference Time Domain (FDTD) algorithm is developed and implemented for the first time in this paper to investigate the diffraction efficiency of a holographic coupler. FDTD simulation is found to be in better agreement with the results of diffraction efficiency for holographic coupler reported in literature using other theories. Further this algorithm is used to investigate the variation of diffraction efficiency with respect to wavelength at different grating period and angle of incidence in three different optical communication windows. It is found that First window is the most suitable for holographic coupler. [ABSTRACT FROM AUTHOR]

The performance of the optical fiber pre-warning system (OFPS) is susceptible to the interference of background noise, especially in the low signal-to-noise ratio (SNR) environment. In this paper, a recognition method based on the multi-level wavelet decomposition is proposed to accurately identify the running and digging intrusion signals in OFPS under the low SNR condition. The method includes the cross-correlation operation, feature extraction, and recognition using a random vector functional-link (RVFL) neural network (NN). Firstly, the collected signals are processed by the cross-correlation operation. Compared with the conventional filtering method, the background noise can be suppressed to the greatest extent by the cross-correlation operation, which keeps the signal details as much as possible. Secondly, the cross-correlation functions obtained from the cross-correlation operation are decomposed into five levels by the multi-level wavelet decomposition. And then the average energy ratios can be obtained along with the decomposed levels, and we select these ratios in the five frequency bands as the feature of intrusion signals. Next, the feature samples are sent into the RVFL NN for training so as to complete the recognition of these intrusion signals. Finally, the effectiveness of the algorithm is verified by the field experiment. [ABSTRACT FROM AUTHOR]

In this paper, the generalized nonautonomous nonlinear Schrödinger equation with non-isospectral parameter is investigated from the point of view of soliton management through modulation of dispersion and nonlinearity. Based on the obtained analytic soliton solutions, the effect of modulated coefficients such as dispersion and nonlinearity on the control of soliton transmission is studied. Especially, controllable soliton interactions are investigated through suitably tailoring the inhomogeneous profiles. Additionally, modulation instability (MI) has been analyzed graphically through linear stability analysis (LSA) and MI gain spectrum is analyzed for various forms of modulated coefficients. Through this study, we confirm that the modulated coefficients in the theoretical model under investigation affect the amplitudes, widths and trajectories of the nonautonomous solitons. Thus, one can obtain the optical control system by choosing the different form of modulated coefficients for the specific problem. Results obtained in this paper would be worthy in the field of soliton management for improving the capacity of optical fiber communication system. [ABSTRACT FROM AUTHOR]

Polarization mode dispersion (PMD) is one of the key effects in optical fibre communication that distorts the transmitted signal. The effect of birefringence on the polarization states of an optical signal leads to broadening of the pulses in an optical fibre. The difference in propagation time of the orthogonal modes in a fibre results in differential group delay (DGD). For proper functioning of a telescope, accurate and stable clock signals will be distributed via an optical fibre network to each of the dishes. This paper presents field PMD measurement that is essential in estimating the expected phase change of the clock signal. The average DGD of a 10.2 km fibre link established to be about 62.1 fs. This study serves to address the applicability of optical fibre network transmission in the distribution of frequency and timing reference signals in the MeerKAT and later phases of the square kilometre array (SKA) telescope. [ABSTRACT FROM AUTHOR]

A novel full-duplex hybrid passive optical network/radio over fiber (PON/RoF) link with 10-Gbit/s 4-ary quadrature amplitude modulation (4-QAM) signal for alternative wired and wireless converged access is proposed. In the central station (CS), optical frequency multiplication (OFM) is implemented to generate millimeter- wave (mm-wave) band optical carrier with three tones via a dual-electrode Mach-Zehnder modulator (DE-MZM). The downlink QAM baseband signal is modulated on one sideband via an optical I/Q modulator. At the hybrid optical network unit (HONU), the downlink converged signal is routed into different receiver modules to achieve wired or wireless access. Moreover, the centralized lightwave separated from the downlink is reused as the uplink optical carrier for either wired or wireless access, and modulated by the baseband or mm-wave data of the uplink alternatively. Since the HONU is free from the laser source, the system complexity and cost are reduced. The simulation results show that our proposed full-duplex hybrid PON/RoF link for the alternative wired and wireless access maintains good performance even when the transmission link with standard single mode fiber (SSMF) is extended to 30 km. [ABSTRACT FROM AUTHOR]

We examine the impact of intermodal dispersion on the modulation instability (MI) of an optical soliton in the Kundu-Eckhaus (KE) equation in the presence of cross phase modulation (XPM), modified saturable nonlinearity (MSNL), and self phase modulation (SPM). We consider the two component KE model with intermodal dispersion and MSNL, but without the four wave mixing term. Because the rays connected to various modes traverse the optical fiber at various effective lengths, intermodal dispersion arises in multimode fibers. As a result, light in the various modes spreads out temporally along the fiber. The MI criterion for the KE equation is established using the traditional linear stability analysis. When XPM and SPM are present, it is possible to determine, how inter modal dispersion and MSNL will impact the MI of an optical soliton in a birefringent fiber using the MI criterion. According to the findings, changed saturable nonlinearity significantly influences the MI dynamical behavior. In a typical dispersion scenario, an increase in the nonlinear saturation parameter can lead to an increase in the MI soliton. However, the anomalous dispersion regime exhibits the contrary behavior. In a two core birefringent KE model, the MSN and intermodal dispersion are capable of producing ultra-short pulses and a soliton. Our research will contribute to increasing the fiber optic telecommunication network's capacity and quality. [ABSTRACT FROM AUTHOR]

Microelectronics focuses on the study of electrons as carriers of electric charge and the control of their specific magnetic transfer by electric fields. It has made great progress in the last century, triggering the third technological revolution in the history of science and technology and bringing science into the information age. However, with the development of small electronic devices, high-capacity chips or high-density information storage materials, microelectronics is facing unprecedented difficulties and challenges. In view of the serious size problem of trace materials in microelectronic devices, it is important to find new ways to dilute and regulate information. TiO2, a semiconductor magnetic material, is an important material in the field of microelectronics and has been widely used in microelectronics. In recent years, it has played an important role in the fields of optical fiber communication and optical fiber detection. Photoacoustics combines the advantages of microwave and optical technologies and offers new possibilities for high quality optical communication as well as response sensors and high resolution. Compared with traditional electronic technology, photoacoustics has the advantages of anti-electromagnetic interference and functional flexibility. As an important breakthrough in computer technology, optoacoustics plays an important role in many fields. Therefore, the application of optoacoustic technology is important for improving the neural network structure based on magnetic materials in TiO2 semiconductors. [ABSTRACT FROM AUTHOR]

Optical fiber communication network security is getting more and more prominent, while the optical fiber communication network monitoring is another challenges of the optical fiber communication network security. In order to Address Resolution Protocol key technology was used. In addition, design of optical fiber communication network detection system was also designed. [ABSTRACT FROM AUTHOR]

We used a Fourth-Order Runge-Kutta in the Interaction Picture Method for simulating supercontinuum generation (SCG) in a designed solid-core photonic crystal fiber (PCF) with zero dispersion wavelength (ZDW) at 800 nm and other solid-core PCF with ultra-flattened dispersion in the range of 1300 nm to 1550 nm obtaining a SCG with a bandwidth of 850, 1200, and 2300 nm using a femtosecond laser in the three communication windows. Here we achieved ZDW close to the first, second and third communication windows which gives us the possibility to obtain a wide spectrum at these points with good quality in the 40-dB bandwidth for SCG with flat spectrum. The design of the two PCFs proposed here is analyzed numerically using finite element method (FEM) and we showed the results when we used a pump wavelength in normal and anomalous dispersion regimes close to ZDW points of these two PCFs for SCG. [ABSTRACT FROM AUTHOR]

An optical network has a major role to play in modern computer networks. The optical network is providing a platform for transmission of huge amount of data at very high speed. These networks may fail due to various reasons. These failures may result in significant loss of revenue and time. Since this loss has a considerable effect on user and service provider, so the survivability of these optical networks has become very important issue to address. The survivability of a network is the capability of network to provide continuous services. The link failure is one of the very common failures in optical networks. A failed link is required to restore accurately and quickly so that failure impact can be minimized. In this paper, we have proposed a method to address survivability in all optical networks in case of single link failure. This method minimizes the recovery time for single link failure. Ant Colony Optimization (ACO) technique along with adjacent shortest cycle is used to calculate alternative path for retransmission of data. [ABSTRACT FROM AUTHOR]

This paper theoretically investigates a comparative analysis of the performance of both graded index perfluorinated plastic optical fiber and alumino-silicate optical fiber in internal optical interconnections operation, where these materials have low dispersion at the operating wavelength 1.3 μm. Temperature dependence of total dispersion coefficient is deeply investigated for these fibers. The temperature variations range from −50 °C to 100 °C. The obtained results show the dramatic effects of increasing ambient temperature variations on the signal quality degradation. The effects of increasing optical fiber length on optical interconnections performance efficiency and operation speed. A comparative study shows that, perfluorinated plastic optical fiber overcomes the alumino- silicate in operation performance efficiency and installation flexibility. [ABSTRACT FROM AUTHOR]

Optical fiber plays an important role as a transmission channel in fiber optic communication. In this work, the design of optical fiber using integration of metamaterial which allows waveguidance through subwavelength geometry is proposed. Transmission of information through surface plasmon mediated or through classical core guidance is made possible, with metamaterial as either core or cladding. Here, the alternate combination of Ag/Al 2 O 3 layers are used, which acts as an anisotropic metamaterial (AMM), supporting plasmonic propagation, depending upon the wavelength (around UV-Region). Parameters such as confinement loss and dispersion characteristics are analyzed for different proportions of metal and dielectric layers. Propagation of desired modes are confirmed by the obtained simulation results by Finite element method. [ABSTRACT FROM AUTHOR]

By employing the time-dependent power flow equation (TD PFE), we examine the bandwidth in multimode W-type (double clad) microstructured plastic optical fibers (mPOFs) with a PMMA (polymethyl methacrylate) solid core for parametrically varying depth and width of the intermediate layer (IL) (inner cladding). The investigated W-type mPOF's bandwidth was calculated for various configurations of the air-holes in the inner cladding and varied launch excitations. We obtained that results for smaller inner cladding air-holes at longer fiber lengths exhibit greater bandwidth. On the other hand, for shorter fibers, the launch beam which only excites guided modes, has no effect on the bandwidth due to the air-hole size. The W-type mPOF with a narrower inner cladding has a greater bandwidth. The bandwidth is also larger for a narrow launch that only excites guided modes as opposed to a wider launch that excites both guided and leaky modes. Therefore, the bandwidth increases as the width of the IL is reduced, or by decreasing the diameter of air-holes in the IL, or by exciting only guided modes. W-type mPOFs can be more easily tailored for a specific use in optical fiber sensors and communications because to their programmable properties. [ABSTRACT FROM AUTHOR]

We theoretically modulate vector soliton molecules in an optical fiber system model, when input orthogonal modes' central wavelengths are the same or different. In the case of same central wavelength with 1064 nm, output orthogonal modes maintain their states in time or frequency domain, when projection angle or phase difference changes. While when orthogonal components have slightly different central wavelengths (2 nm wavelength difference), energy flow occurs when projection angle varies. Our results are applicable to polarization-multiplexed optical fiber communication, ultrafast optical fiber laser and so on. [ABSTRACT FROM AUTHOR]

Optical communication system is a kind of communication system using the light wave as the carrier. It has been widely used in recent years with the advantages of the long distance. Optical solitons have some merits for high stability, amenable to generate and low cost, it is an ideal carrier of optical communication system. In this paper, the regulation of pulse characteristics of the optical soliton is studied theoretically. The influence of high-order dispersion and high-order nonlinear effects on the amplitude, shape and other transmission characteristics of the optical soliton is studied by using the bilinear method with the high-order variable coefficient nonlinear Schrödinger (NLS) equation in the nonuniform fibers, and the regulation problems such as the maintenance and excitation of the optical soliton are analyzed. The waveform and amplitude control of the optical soliton and the change of optical soliton characteristics with the dispersion management are studied profoundly, and the nonlinear dynamic processes in their respective intracavity are analyzed. A feasible scheme for avoiding and utilizing the optical soliton is proposed, which has the significance for the investigation of the parameter regulation and dynamic control of the optical soliton in practical inhomogeneous optical fiber communication systems. [ABSTRACT FROM AUTHOR]

An optical fiber pre-warning system (OFPS) can forecast pipeline leakage and prevent serious losses occurring in the field of pipeline transport. Vibration signals of OFPS normally consist of noises, harmful and harmless intrusion signals. With the increase of the surface surrounding complexity along with the buried pipelines, the harmful or harmless intrusion vibration signals will increase seriously. This will be a challenge for the traditional recognition method identifying the harmful intrusion vibration. So it is necessary to add an effective and efficient vibration signal detection link before the traditional recognition method. Only in this way, the noises and harmless intrusion signals can be eliminated effectively, and the data quantity of the late recognition will be decreased greatly. Hence, a new two-dimensional method to detect harmful intrusion vibration for an OFPS is developed in this paper. Two basic features of vibration data, the background homogeneity and the frequent degree of harmless intrusions, are focused to develop the new two-dimensional detection method for OFPS. In the part of space-dimensional detection, two types of Constant False Alarm Rate (CFAR) method, CA-CFAR and GO/SO-CFAR, are used to detect the total vibration data according to the different background homogeneity, respectively. In this way, the huge number of noise signals can be eliminated effectively. In the part of time-dimensional detection, two test methods, Sequential Probability Ratio (SPR) test and Kolmogorov – Smirnov (K – S) test, are adopted to detect the remaining vibration data according to the different frequent degree of harmless intrusions which are obtained by prior information. The harmless intrusion signal data and false alarm data can be eliminated largely. The proposed two-dimensional method is applied to detect the measured field vibration data, which were collected by an OFPS in Rushan of Shandong, China. The analysis results show that the harmful intrusion signals can be detected rapidly and accurately from the complex and huge measured data. Further, the proposed method can ensure a steady false alarm probability in space-dimensional detection and improve the detection performance of harmful intrusions effectively. [ABSTRACT FROM AUTHOR]

Photonic time stretched analog-to-digital converter (PTS-ADC) utilizes a broadband optical source and dispersion medium to expand the capabilities of electrical digitizers, achieving real-time sampling with high resolution. In order to minimize used fiber length and simplify PTS-ADC equipment, large dispersion photonic crystal fiber (PCF) is used as dispersion medium. In this letter we demonstrated the impact of optical nonlinearity on PTS-ADC based on large dispersion PCF performance as compared with single mode fiber (SMF) and dispersion compensation fiber (DCF). It is stimulated that dispersion penalty null frequency of fundamental tone will shift using three fibers when nonlinearity is added. In comparison, SMF is most insensitivity by changing input optical power, then PCF. However PCF is most insensitive by changing pulse width. Meanwhile, PCF is best to suppress 3rd-order harmonic distortion according to carrier-to-interference ratio (CIR) in three fibers. PCF is the most suitable as broadening medium in PTS-ADC. [ABSTRACT FROM AUTHOR]

High-order quadrature amplitude modulation (QAM) is a promising approach for increasing the spectral efficiency of wavelength-division-multiplexing transmission, but its optical implementation is still challenging. We propose a customized IQ modulator for generating 64-QAM using equal-amplitude electrical binary drive signals and verify the operation through simulations. Using the embedded VOAs, the transmitter can be finely controlled and flexible for several modulation formats. [ABSTRACT FROM AUTHOR]

A location method based on the Lissajous figure is proposed for fiber-optic distributed disturbance sensor based on Mach–Zehnder interferometer. The disturbance is located by the fiber-optic distributed disturbance sensor due to the time delay between the two signals from clockwise and counter-clockwise Mach–Zehnder interferometers. In the Lissajous figure of the two signals, a fitting ellipse with constant semi-major and azimuths is induced to evaluate the time delay. The relationship between the time delay and semi-minor of the ellipse is obtained by linear fitting. Then, the time delay can be calculated by the semi-minor of the fitting ellipse. In the experiment with 2 km long fiber and 4 MHz sampling frequency, the maximal location errors with Lissajous figure based method and current cross correlation function based method, without phase generation carrier technique, are 75 m and 1.25 km, respectively. It seems to be that our proposed Lissajous figure based method is a useful for improving fiber-optic distributed disturbance sensor. [ABSTRACT FROM AUTHOR]

Optical soliton is a nonlinear wave with huge information or data which travels over larger distance in optical fibers. This paramount application of optical soliton forced many mathematicians and physicians to focus on it which initiates to study the soliton solutions of mathematical model in optical fiber communication characterized by nonlinear Schrodinger equation (NLSE) along with its important applications. Nonlinear Schrodinger equation represents propagation of light pulse through an optical fiber. In this paper NLSE is solved numerically by using exponential cubic B-spline differential quadrature method. In this method leave-one out cross validation strategy is being used to find optimal value of parameter p which enhances accuracy and efficiency of its results which are near to exact solutions and approximate to available numerical solutions in the literature. [ABSTRACT FROM AUTHOR]

Er3+-doped BaNaB glasses with 0.5, 1.0, 2.0, 3.0 and 4.0 mol% of Er3+ were prepared by melt-quenching technique for study their luminescence properties in NIR and visible regions. The absorption spectra showed the absorption bands at 381, 406, 451, 488, 522, 545, 653, 804, 977 and 1532 nm in UV-Vis-NIR region. The NIR emission spectra, excited with 977 nm, show the broad band centered at 1540 nm in the range of 1460–1625 nm covers the S, C and L bands that have low transmission loss region in fiber-optic communication. The glass sample with 3.0 mol% of Er3+ provides the highest intensity of NIR emission. From the Judd-Ofelt analysis and McCumber theory, the glass sample with 4.0 mol% of Er3+ show the best performance for use as a broadband amplifier with the high gain bandwidth at 633.64 × 10−28 cm3 and the high emission cross section at 7.51 × 10−21 cm2. For the emission in visible region, when excited with 349 nm, the glass sample with 3.0 mol% of Er3+ provides the most intense emission in yellow-green region, when excited with 402 nm, the glass sample with 4.0 mol% of Er3+ provides the most intense emission in green region. The results from the McCumber theory and gain efficiency show good agreement of the glass sample with 4.0 mol% of Er3+ for use as broadband amplifier in C and L communication windows when the population inversion is more than 50%. [ABSTRACT FROM AUTHOR]

In this paper, an optical fiber fault location method based on OCDMA coding is presented, which may accurately locate branch fault at local side and enlarge dynamic range through coding gain while ensuring relatively small discrimination. According to the experiment, dynamic range of the method may support PON optical fiber fault detection with branching ratio of 1:128 and transmission distance of 20 km, and the discrimination is about 10 cm. Peak value of the received signal is improved from 40 mV to 2.1 V, which successfully verifies the feasibility of the design scheme. [ABSTRACT FROM AUTHOR]

A novel photonic crystal fiber (PCF) based on a four-hole unit is proposed in order to meet the requirements of high birefringence, negative dispersion and confinement loss in fiber-optic communication. The proposed design has been simulated based on the full vector finite element method (FVFEM) and anisotropic perfectly matched layers (APML). Analysis results show that the proposed PCF can achieve a high birefringence to the order of 10 −2 at the wavelength of 1.55 μm, a large negative dispersion over a wide wavelength range and confinement losses lower than 10 −9 dB/m simultaneously, which has important applications in polarization-maintaining (PM) fibers, single-polarization single-mode (SPSM) fibers, dispersion compensation fibers and so on. [ABSTRACT FROM AUTHOR]

In order to overcome the deterioration of system performance induced by the subcarriers at or near the deep fading nulls in high frequency band-pass regions of multimode fiber, we first propose adaptive unsaturated OFDM technique based on zero padding in this paper. In our proposed method, the subcarriers with low SNR (at or near deep fading nulls) are turned off by zero padding, and data originally transmitted by those subcarriers will be transferred to new subcarriers with high SNR which have been created at high frequency by the adjusting of IFFT points. The results show that the technique proposed can accomplish transmission of 10 Gbps data rate over 1 km multimode with the BER of 4.61e−3 when the OSNR is 20 dB. [ABSTRACT FROM AUTHOR]

In secure communication systems, a very important problem is how to prevent wiretapping. Lots of researches on cryptography give good solutions on secure communications. But if a wire tapper can detect the existence of the transmitted information and get enough eavesdropped frames, cryptanalysis techniques can help to blindly recover the frame structures, error-control coding parameters and passwords. In this paper we propose a novel secure transmission scheme on the link level for optical fiber communication systems. Based on the blind frame synchronization technique, we propose to drop the traditionally strict frame structures in fiber communications and conceal the error-correcting-encoded blocks among random data, so that wire tappers cannot get enough coded packets to analyze and recover the transmitted information. Therefore, the proposed method is very suitable for secure communications and military communications. [ABSTRACT FROM AUTHOR]

This paper intends to investigate the modulational instability (MI) criterion of two core positive-negative index coupler channel setup from the obtained analytical dispersion relation for MI gain profile. The governing equation, the modified nonlinear Schrodinger equation (MNLSE) is studied for the role of higher order dispersion (HOD) and higher order nonlinearity (HON) on instability spectra of two core positive indexed coupler (PIM) and negative indexed coupler (NIM) arrangement. The HOD comprises of the second, third, fourth and fifth order linear dispersion terms and HON is inclusive of cubic, quintic, septic, cubic-quintic-septic-self-steepening (SS), and cubic-quintic-septic-intrapulse Raman scattering (IRS). Our study reveals that it is the 6th order linear dispersion term which brings in the considerable changes of MI gain spectrum in both normal and anomalous dispersion regimes. In particular, the combined effect of septic SS and IRS in two core directional coupler with NIM channel proves to be very crucial in the generation of instability gain spectra. This study has higher prospects in generation of solitary wave in two core directional system for optical fiber communication. [ABSTRACT FROM AUTHOR]

We propose and demonstrate a novel scheme for realizing large refractive index with vanishing absorption in a three-level quantum system consisting of the energy levels of Er 3+ -doped ZrF 4 –BaF 2 –LaF 3 –AlF 3 –NaF (ZBLAN) optical fiber. It is found that the refractive index of the probe field can be controlled via the coherent coupling field and incoherent pumping field. The switching from negative refractive index to positive refractive index and manipulation of the value of the index of refraction while maintaining vanishing absorption of the probe field can be achieved via tuning the detuning of the coherent coupling field. Our scheme may provide some new possibility for technological applications in fiber communication. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, a fiber optic communication system has been employed using co-existing 10G/2.5G asymmetric gigabit passive optical network (XG-PON) architecture. In this system, bidirectional optical fiber has been used for upstream and downstream data transmission. The system performance has been investigated for non-return-to-zero (NRZ) and return-to-zero (RZ) data formats operating at varying bit rates by varying the length of the fiber for analyzing the feasibility of this co-existence. The results have been compared for NRZ and RZ formats for upstream and downstream data in terms of Q value and eye opening. It is observed that RZ modulation format is superior as compared to conventional NRZ format and the faithful transmission of signal has been carried up to 90km at 1577nm for downstream and 140km at 1270nm for upstream. [Copyright &y& Elsevier]

Abstract: This paper delineates a novel coding technique, a combination of coding and multiplexing technique, known as mapping multiplexing technique (MMT). A mapping algorithm is used to multiplex four channels, each of which running at 10Gbit/s. Up to four bits per symbol at a symbol rate of 10Gboud was successfully transmitted over a single wavelength. Compare to the conventional return to zero (RZ) and none-return to zero (NRZ)-time division multiplexing (TDM) more than 75% and 50% reduction in the spectral width are achieved, respectively. Calculated chromatic dispersion tolerance of ±130ps/nm is achieved for the 40Gbit/s MMT transmission system at the expense of ∼2dB degradation in the receiver sensitivity (compared to NRZ) due to an increase in the number of levels and in the signal dependency of signal-spontaneous beat noise. In comparison with conventional 4-ary system, the proposed system depicts ∼6.5dB improvement in terms of receiver sensitivity. [Copyright &y& Elsevier]

Abstract: An adaptive terminal dispersion compensation and demodulation scheme based on dual-feedback strategy for 40Gbps return-to-zero differential quaternary phase shift keying (RZ-DQPSK) fiber communication receivers is proposed to achieve high reliability receiving performances. In the receiving system introduced in this paper we utilize both the balanced receiver feedback and framer error rate to achieve accurate RZ-DQPSK optical signal demodulation and adaptive dispersion compensation. Compared to traditional RZ-DQPSK receivers, the proposed design combines the chromatic dispersion (CD) compensation and Mach-Zehnder interferometer (MZI) adjusting and automatically estimates the dispersion compensation parameters without human intervention. And another improvement is introducing the framer error rate as feedback quantity to ensure the accuracy of CD and MZI adjusting. Finally, we present the performance of the designed receiver by showing the simulations and experiment results in actual telecommunication engineering projects. [Copyright &y& Elsevier]

Abstract: In this paper, low cost solution based on RSOAs is proposed for a high capacity 32×32 channel, 20km, FTTH duplex link employing triple play services. Here, downstream transmitters generate a 2.5-Gbps NRZ signal which is routed to both receivers and RSOA-based upstream transmitters. The RSOA modulates this signal with a 1.25-Gbps NRZ signal that effectively overwrites the downstream signal and then it is transmitted back over the same 20km of bidirectional fiber, where it is routed to receivers at the CO. The proposed model completely eliminates the requirement of separate lasers for upstream communication which makes the system very cost effective. The high-pass filtering effect of the RSOA becomes predominant at higher input powers which has been used as an advantage here to effectively suppress the downstream signal. The impact of RSOA input power and extinction ratio of the downstream signal have been investigated and reported. [Copyright &y& Elsevier]

Abstract: We investigated the transient and steady-state processes of a probe field in an optical fiber. It is found that the nonlinear processes can be easily controlled via the coherent field and incoherent pumping field. The underlying mechanisms are much more practical than those in atomic systems, which may provide some possibilities for technological applications in optical-fiber communication. [Copyright &y& Elsevier]

To reduce the saturation voltage of fiber filter and improve the sensitivity of voltage sensing, we propose and numerically demonstrate a multifunctional optoelectronic device with a flat-plate photonic crystal fiber structure in this paper. One of the air holes is selectively filled with liquid crystal, and the upper and lower planes of the fiber are plated with gold films to form electrodes. Based on the applied voltage, the coupling wavelength of the core fundamental mode and filling mode is adjusted. This structure can realize the functions of tunable filtering and external voltage sensing. In addition, the metal film is close enough to the fiber core to enable coupling between the core waveguide mode and the surface plasmon resonance mode. Thus, the external RI can be measured. The measurements of the voltage and refractive index of the device are independent of each other, thus realizing a simultaneous measurement of the two parameters. We used the finite element method to investigate its photoelectric characteristics systematically. When the thickness of the plate fiber is 18 µm, as a fiber filter, the applied saturation voltage decreases from 2900 V (photonic crystal fiber with a conventional structure) to 650 V, and the threshold voltage decreases from 45 to 8 V. When used as a voltage sensor, the voltage sensitivity is improved from 0.025 to 0.117 nm/V. As a dual-parameter sensor for simultaneously measuring the voltage and RI, the RI sensitivity is 2700 nm/RIU. Evidently, the superior performance of the proposed structure renders it a high application value in the fields of optical fiber sensing and communication. [ABSTRACT FROM AUTHOR]

To reduce the saturation voltage of fiber filter and improve the sensitivity of voltage sensing, we propose and numerically demonstrate a multifunctional optoelectronic device with a flat-plate photonic crystal fiber structure in this paper. One of the air holes is selectively filled with liquid crystal, and the upper and lower planes of the fiber are plated with gold films to form electrodes. Based on the applied voltage, the coupling wavelength of the core fundamental mode and filling mode is adjusted. This structure can realize the functions of tunable filtering and external voltage sensing. In addition, the metal film is close enough to the fiber core to enable coupling between the core waveguide mode and the surface plasmon resonance mode. Thus, the external RI can be measured. The measurements of the voltage and refractive index of the device are independent of each other, thus realizing a simultaneous measurement of the two parameters. We used the finite element method to investigate its photoelectric characteristics systematically. When the thickness of the plate fiber is 18 µm, as a fiber filter, the applied saturation voltage decreases from 2900 V (photonic crystal fiber with a conventional structure) to 650 V, and the threshold voltage decreases from 45 to 8 V. When used as a voltage sensor, the voltage sensitivity is improved from 0.025 to 0.117 nm/V. As a dual-parameter sensor for simultaneously measuring the voltage and RI, the RI sensitivity is 2700 nm/RIU. Evidently, the superior performance of the proposed structure renders it a high application value in the fields of optical fiber sensing and communication. [ABSTRACT FROM AUTHOR]

Abstract: In this work, we investigate the performance of a distributed power control algorithm (DPCA) for signal-to-interference (SIR) optimization in wavelength-hopping time spreading code routed networks. These networks are based on 2D codes (time/wavelength) to establish end-to-end optical code paths (OCPs). The SIR model considers multiple access interference (MAI) between OCPs and amplified spontaneous emission (ASE) at cascaded amplified spans. The utilization of power control has a significant impact on both performance and capacity of practical optical networks. The DPCA can be effectively implemented in each node because uses only local parameters or measurements. [Copyright &y& Elsevier]

Abstract: For the first time to the best of our knowledge the effect of guard band (GB) on the performance of 40Gb/s Absolute Polar Duty Cycle Division Multiplexing (AP-DCDM) over a single wavelength and wavelength division multiplexing (WDM) are investigated and reported. It is demonstrated that the spectral width occupied by 40Gb/s AP-DCDM with GB is 100GHz (with minimum spectral efficiency of 0.4b/s/Hz) whereas, this value can be reduced to around 80GHz for AP-DCDM without GB (with minimum spectral efficiency of 0.5b/s/Hz). In addition to better spectral efficiency, this amount of saving in the spectral width leads to ∼60ps/nm improvement in chromatic dispersion tolerance. In this paper, characteristics of AP-DCDM with and without GB over WDM system are compared at the speed of 40Gbit/s per WDM channel, for the tolerance to narrow optical filtering and minimum allowed channel spacing. The AP-DCDM without GB has narrower spectral width than AP-DCDM with GB, which makes its implementation in WDM system advantageous. [Copyright &y& Elsevier]

Abstract: A multichannel double-polarization bandpass optical filter, which has the performance of variable channel interval, is theoretically proposed. The filter consists of a stack of two one-dimensional photonic crystals (1D PCs). Based on the resonant couple of evanescent waves localized at the interfaces between neighboring layers, the linear transmission properties of the filter are numerically simulated by the transfer matrix method. The simulation results show that channel number of the filter can be changed by varying the thickness of the middle layer in the centrosymmetric 1D PC structure, while the bandwidth and wavelength of the channel can be adjusted by the incident angle of light. This work may be helpful in designing multichannel double-polarization bandpass optical filter in optical communication systems. [Copyright &y& Elsevier]