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In this present work, we retrieve the optical solitons in birefringent fibers modeled by Radhakrishnan-Kundu-Lakshmanan (RKL) equation in coupled vector form. The system is composed of self-phase, cross-phase modulation terms, self-steepening terms and the effect of four-wave mixing is discarded. In this article, by employing innovative integration norms known as the extended rational sine-cosine/sinh-cosh techniques different forms of optical solitons like dark, singular, combined and complex soliton solutions are recovered. Furthermore, singular periodic wave solutions are also observed. The constraint conditions which ensure the formation of soliton solutions are also specified. By using the suitable values of the parameters involved, the 2-, 3-dimensional and the contour graphs of some of the reported solutions are plotted. The stability of the given model is studied by exercising the modulation instability analysis which confirms that the model is stable and guarantees that all extracted solutions are stable and exact.

This article discusses the nonlinear effect, four-wave mixing (FWM), which lowers the performance of optical communication systems. The concept of orthogonal polarization was introduced to reduce the effects of FWM. Here, orthogonal polarization is used with various modulation techniques such as NRZ, RZ, GAUSSIAN and RAISED COSINE. Orthogonal polarization was found to reduce the effect of FWM more than round polarization. Weaknesses of the four wavelength mixes were analyzed for various levels of input power. The capacity of a four-wave mixing product (FWM) is assessed by an optical spectrum analyzer. System performance is analyzed in terms of quality factors and BER.

In this paper, the auxiliary equation mapping method is employed to extract optical solitons and other solutions for special cases of Kudryashov’s model in birefringent fibers that is studied without the effect of four wave mixing effects. Bright, dark and singular solitons and other solutions emerge from the auxiliary equation mapping method.

Vectorial four-wave mixing of low-power ultrashort laser pulses in a highly nonlinear fiber with a properly optimized dispersion profile is shown to enable an efficient generation of high-quality photon pairs with photon-pair count rates above 10 6 pairs/(s mW). A superbunching regime of photon-pair generation with the correlation coefficients g ( 2 ) ( 0 ) exceeding 1200 is demonstrated with pump powers p as low as 0.1 mW. Very low values of heralded-photon correlation coefficients, g c 2 0 3 ⋅ 1 0 − 3 , achieved in the low-p regime reveal a strong antibunching in the signal-photon channel, indicating that more than 99.7% of the signal counts correspond to truly single-photon states.

For coherent orthogonal frequency-division multiplexed (CO-OFDM) system, four-wave-mixing (FWM) noise is a major limiting factor. A scheme of phase-conjugated twin waves (PCTW) which co-propagates a signal with its phase-conjugated copy along optical fiber link, can be used to reduce the impact of FWM noise. Including walk-off between subcarriers, semi-analytic models of FWM noise are derived here for quadrature amplitude modulation (QAM) CO-OFDM system with three PCTW schemes implemented in time, subcarrier and polarization domains, respectively. We show that many phase-conjugated twin FWM components can be obtained in such system and they can be added destructively at the receiver, so the total FWM noise can be reduced, but some FWM components have not their phase-conjugated twins for the subcarrier-domain PCTW scheme. Some phase-conjugated twin FWM components are generated from different FWM collision processes for the time-domain PCTW scheme, as will reduce the effect of the PCTW scheme The calculative results obtained by using our semi-analytical model show that the polarization-domain PCTW scheme excels the other two schemes in improving the nonlinear tolerance of such system and the three PCTW schemes are all better than a partial carrier filling (PCF) technique.

The interaction force in the four-waving mixing of a two-level atoms system is analyzed. A new rate equation and the formula of the optical force are obtained. By simulation and analysis with MATLAB software, the impulse curve is obtained. The impulse increases with probe-wave detuning increasing and then tends to saturation. When the Ra-bi frequency takes a certain value, the impulse can obtain relative maximum and the relative maximum increases with the Ra-bi frequency increasing. The relation between the most value and the parameters of Ra-bi frequency and probe-wave detuning is also researched. The impulse occurs minimum when probe-wave detuning is zero and Ra-bi frequency is zero, there is no maximum for the impulse, which is close to 0.02 infinitely, the lowest temperature that can be reached is 248 μk. In addition, T2/T1 also has a significant influence on the impulse.

In this work, we demonstrate a wide-spectrum multi-wavelength fiber laser generated by Brillouin-comb assisted four-wave mixing (FWM). The mechanism of the laser is based on the combination of stimulated Brillouin scattering in cavity and multiple FWM process outside cavity. The experiment results demonstrate that Brillouin-comb assisting is an effective method to improve the FWM process and increase the line number. More than 110 lines are achieved in 10 nm spectral range with the wavelength spacing of ∼ 0.09 nm. The multi-wavelength fiber laser exhibits good stability on both the operating wavelengths and output power. The tunability of this multi-wavelength fiber laser is improved significantly by inserting a tunable filter in the cavity. The total line number is kept more than 110 in the whole tunable range of 30 nm from 1540 to 1570 nm.

Four Wave Mixing (FWM) is one of the main transmission impairments in coherent optical systems and a broad gamut of analytical expressions calculating its power already exists in the literature. Most of these expressions, such as the GN-model, assume that due to the large values of accumulated dispersion, each transmitted signal behaves as stationary circular Gaussian noise, ignoring the dependence of FWM on the employed modulation format. This assumption leads to significant error especially in the case of quadrature-phase-shift keying (QPSK), in systems with small number of spans and in the dispersion managed case. In addition, the GN-model is inaccurate when applied to metro networks, due to the low accumulated dispersion. In this paper, we derive closed-form expressions which incorporate the impact of modulation format on FWM generation, extending and improving the accuracy compared to existing closed-form FWM expressions. Moreover, the proposed method includes terms that make it applicable to systems with small span lengths (

In this paper, we demonstrate homodyne tomography on a narrow-band heralded single photon generated from spontaneous four-wave mixing process in a cold atomic cloud. This is the first work that shows the photon-number state of the narrow-band single photons transmitted through electromagnetically-induced transparency window. The Wigner function of the optical state is demonstrated as a non-Gaussian state. The homodyne tomography provides an important route to characterize the single-photon source.

To meet the growing internet data traffic, transmission capacity of fibers has to be increased. For that Dense Wavelength Division Multiplexing (DWDM) technique has been used nowadays. However, there is a nonlinear distortion which degrades the transmitted signal and hence decreases the overall system performance. The nonlinearities that arise in WDM systems are Cross Phase Modulation (XPM), Stimulated Raman Scattering (SRS) and Four Wave Mixing (FWM). Also it is found that these nonlinearities depend upon input power, dispersion and channel spacing. In this paper two methods have been proposed to eliminate FWM and SRS effect. Firstly, the fiber optic link has been analyzed by increasing the input power. From the analysis it is found that the FWM effect get increased by increasing the input power. But the transmission power should be optimum to transmit the information in long haul fiber optic link. The FWM effect is reduced by placing the Circular Polarizers alternatively in each transmitter before passing through the fiber link. Another method which has been proposed to eliminate SRS is optimum allocation of input power. The unwanted power tilt due to SRS effect is reduced by allocating the transmitted power randomly. The simulation studies are carried out using OPTSIM and OPTISYSTEM software. The simulations have been carried out for multichannel systems with equal spacing. It is found that the optimum power level allocation also improved the system performance.

Optical solitons called bright soliton, dark soliton together with singular soliton solutions were emerged in this work. Dense wavelength division multiplexed (DWDM) system with the inclusion of four-wave mixing as well as spatio-temporal dispersion additionally group-velocity dispersion for such forms kerr and parabolic law of fiber was analyzed through the medium of trial equation integration approach. Besides these optical soliton solutions, supplement solutions referred to as singular periodic solutions were formed.

Fiber-optical parametric amplifier has currently drawn interest of research for evolving efficient broadband amplification in optical communication network. This paper presents dispersion flattened highly nonlinear fiber’s role as a fiber optic parametric amplifier. This study has been carried out with single pump in the novel highly nonlinear ultra-flattened dispersion shifted fiber (HN-UFF) that was designed by us earlier. This paper also discusses the impact of length of such HN-UFF, pump signal power, input signal power and pump signal wavelength on fiber optic parametric gain. Simulation results reveal that a high value of fiber optic parametric gain of about 15 dB and respective bandwidth of over 600 nm can be achieved by properly utilizing the high nonlinearity and ultra-flattened dispersion of the HN-UFF. Since parametric amplification follows the Four wave mixing technique, in addition to good amplification, an effective wavelength conversion can also be carried out over a wide range of 600 nm in future.

Optical solitons namely dark, bright with singular solitons have been recovered for Gerdjikov–Ivanov equation along with four-wave mixing terms in birefringent fibers in this current study. Trial equation integration procedure is employed to get not only such strategic solitons but also singular periodic solutions.

The dynamics of solitons in birefringent optical fibers with weak nonlocal nonlinearity is studied in this paper, in presence of four-wave mixing terms in the governing model. There are three main types of exact one-soliton solutions retrieved for this dynamical system. The approach is based in the modified sub-equation extended method for the generalized hyperbolic and trigonometric functions for constructing new exact solutions of the governing coupled equations in birefringent optical fibers. Several constraint conditions naturally fall out during the course of integration of the corresponding coupled nonlinear partial differential equations.

By simulating the structure of half Panda waveguide base on nonlinear material, it was able to generate the four-wave mixing base on 3 picks which the highest pick was pump and the lowest power goes to converted. In this research the high Qfactor showing the optimization for the waveguide was successful which was 2.58 × 103 in drop port. better power transferring occurred with the nonlinear material has been used. It has been found that signal and pump intensity were higher than the converted values. Finite different time domain (FDTD) is the simulation that has been used in this modeling.

The coupled system corresponding to Gerdjikov–Ivanov model with the inclusion of four-wave mixing terms is employed to obtain optical solitons of its in this work. The modified simple equation technique is used to obtain both solitons namely dark, bright with singular solitons and singular periodic solutions.

We experimentally demonstrate Q-switched and mode-locked Erbium-doped fiber laser (EDFL) by using topological insulator (TI) Bismuth Selenide (Bi2Se3) as saturable absorber (SA). The fabricated Bi2Se3 SA exhibits modulation depth and saturation intensity at 39.8% and 90.2 MW/cm2, respectively. By incorporating the fabricated Bi2Se3 SA into the laser cavity, Q-switching operation is generated with repetition rate ranging from 23.5 kHz to 68.2 kHz, pulse width ranging from 2.4 μs to 8.6 μs and maximum peak power is calculated at 19.9 mW. Our cavity can also generate soliton mode-locked pulse with repetition rate of 23.3 MHz and pulse width of 0.63 ps by inserting an additional 5 m long single mode fiber (SMF) into the existing laser cavity. Spectral peaks due to Kelly side-bands and four wave mixing (FWM) were observed on the soliton spectrum. Both Q-switching and mode-locking pulses are stable in the laboratory environment, allowing the realization of compact and low cost pulsed fiber laser with Bi2Se3 SA for various photonics applications.

A theory analysis of the four-wave mixing (FWM) scheme in a double asymmetry quantum dots (QDs) system is performed. The efficiency of the generated field decreases in an oscillating mode for the penetration depth and is significantly enhanced because of three-wave mixing (TWM). The dependence of the conversion efficiency on the three coupling laser fields and decay rate is also discussed. High conversion efficiency up to 0.8 is demonstrated with small propagation length at low temperature. Such a solid-state system may be more practical due to the flexibility of QDs to generate coherent short-wavelength radiation.

In this paper, we present a theoretical analysis of four-wave mixing (FWM) between short optical pulses in a photonic crystal semiconductor optical amplifier (PC-SOA). The proposed model is based on a nonlinear propagation equation by taking into account self-phase modulation (SPM), carrier density pulsations (CDP), carrier heating (CH), and spectral-hole burning (SHB). To analyse the FWM in a PC-SOA, pulse evolution in a temporal and spectral domain are investigated. Also, the optical fluid method is used in the photonic structure for design and engineering an appropriate bandwidth with constant group index to analyse the FWM mechanism. The bandwidth is designed in the L-Band region of telecommunication optical networks. Based on calculated results, it is depicted that for low energy short pulses, the conversion efficiency (CE) of PC-SOA is higher than conventional SOA. Furthermore, it is shown that, by increasing the injection current the CE is increased.

This paper retrieves optical solitons in birefringent fibers having non-local nonlinearity in presence of four-wave mixing. Phase-matching conditions have been implemented to display these solitons. Bright, dark and singular soliton solutions are revealed. Department of Mathematics and Statistics at Tshwane University of Technology South African National Foundation --- 92052 IRF1202210126 National Research Foundation of Korea --- NPRP 8-028-1-001 Qatar National Research Fund (QNRF)

The F-expansion scheme reveals bright, dark and singular optical soliton solutions in birefringent fibers for quadratic–cubic nonlinearity. Apart from soliton solutions, additional forms of solutions in terms of Jacobi's elliptic function and Weierstrass elliptic functions are recovered. Singular periodic solutions are also obtained as limiting case to Jacobi's elliptic functions.

Finite-difference time domain (FDTD) simulation has been used for modeling of nonlinear optical interaction in a modified microring resonator as Panda structure. By proposing the Panda structure which has been modeled using both silicon and material (Chi2) with nonlinear effect, generation of four-wave mixing is feasible. Due to the nonlinear interaction between the two input waves as pump and signal within the microring resonators the results show the generation of three picks including the pump, signal and converted wave. In the case, if the silicon has been utilized as the core waveguide, the resonance interferences occur, where the high Qfactor of the resonance frequencies was obtained as 3.87 × 103 in the drop port outputs. Compared to silicon material, the nonlinear material shows a better power transferring performances. In the results showing the four-wave mixing, the converted wave has a lower power than the signal and pump.

The development of ultra-bright extreme ultraviolet (EUV) and X-ray free electron laser (FEL) sources has enabled the extension of wave-mixing approaches into the short wavelength regime. Such a class of experiments relies upon nonlinear interactions among multiple light pulses offering a unique tool for exploring the dynamics of ultrafast processes and correlations between selected excitations at relevant length and time scales adding elemental and site selectivity as well. Besides the availability of a suitable photon source, the implementation of wave mixing methodology requires efforts in developing the instrumental set-up. We have realized at the FERMI FEL two dedicated set-ups to handle multiple FEL beams with preselected parameters in a non-collinear fashion and control their interaction sequence at the target. These unique apparatuses, combined with the exceptional characteristics of the seeded FERMI FEL, have allowed us to make the first steps into this field and further advances are foreseen in the near future.

Nonlinear models previously reported for coherent optical fiber transmission have been used to explain the mechanism of nonlinear noise squeezing by phase-conjugated twin waves (PCTW) scheme, but the reduction of four-wave-mixing (FWM) noise by the nonlinearity mitigation method cannot be directly derived from these models for a quasi-symmetric dispersion map, especially when the effect of walk-off between channels is included. Semi-analytic models based on a statistical method are derived herein order to quantify the reduction of FWM noise for quadrature amplitude modulation (QAM) PCTW Nyquist-WDM systems. Our models derived here show that the variance of non-degenerate FWM noise is irrelevant to the number of signal points within a QAM constellation diagram, as is different from the degenerate FWM case. Numerical results by using our models show that even though the effect of walk-off is included, the PCTW scheme is still greatly effective to reduce the impact of FWM noise for a quasi-symmetric map. The performances of central channel for two cases of 16QAM PCTW Nyquist-WDM systems with same total spectral bandwidth and spectral efficiency, 16-channel 32-Gbaud/ch and 32-channel 16-Gbaud/ch, are numerically compared by using our models

An ultrasensitive refractive index sensor based on the four-wave mixing in a suspended-core microstructured fiber (SC-MOF) is proposed. It presents that, due to much power penetration into the air holes of the SC-MOF, the refractive index (RI) sensitivity is up to 2.43 × 105 nm/RIU for the produced idler wave of the four-wave mixing in SC-MOF. The RI responses of idler wave and signal wave are analyzed as pump wavelengths locate in the normal dispersion region and anomalous dispersion region, respectively. The simulation results show that, if the pump wavelength locates in normal dispersion region and the idler wave is used for wavelength-encoded demodulation, it would be more appropriate for RI sensing. The influence of incident power on RI sensitivity, power fluctuation induced RI measurement error and sensing quality are also analyzed. It is demonstrated that moderate incident power must be selected, and pump wavelength away from transition point would be beneficial for RI measurement stability.

Orbital angular momentum (OAM) of light has attracted much attention because of its applications in many fields. Electromagnetically induced transparency (EIT) is well known as an effective method to manipulate the light fields. Now there are some increasing interests in using the EIT technology to manipulate OAM. In this work, we experimentally report on arithmetic operation of OAM of light in a solid driven by EIT. In an EIT four-level double lambda configuration, we use the optical vortex beams carrying OAM to perform slow-light four-wave mixing (FWM) without experiencing EIT storage. The conservation of OAM is satisfied in this FWM process, and the topological charge of the generated FWM signal is determined by those of the applied fields. The slow-light FWM signal accumulates the total OAM of the applied laser fields. The arithmetic operation of addition, subtraction and cancellation of OAM is effectively performed in experiment. Such OAM manipulation could have practical applications in information processing and quantum information.

This article reviews the nonlinear effects in optical sensors utilizing photonic crystal fiber innovation, which is recently embraced except conventional optical fibers because of their special geometric structures. PCFs have some excellent properties. It will center the most acquainted detecting application with their predictable parameters and discernment. Various PCF sensors are accessible in neoteric age. Analysts and technologists are working on photonic crystal fiber with more than 15-20 application regions. In this article, biosensor applications have been reviewed with their various types. This article has been discussed about the sensor in the form of humidity, gas, PH, liquid, temperature, curvature, torsion, vibration, pressure, refractive index. Optical sensing standards depicted in this article with nonlinear effects namely Surface-enhanced Raman scattering and Four-Wave Mixing.

Light beams with broad spectral bandwidth are indispensable for the generation of ultrashort light pulses. Here, the generation of broadband ultrashort light pulses from narrowband seeds in transparent media is demonstrated. Broadband light pulses with a spectral width of hundreds of nanometers can be generated seeding with narrowband light pulses. The full spectral bandwidths of the narrowband seeds are several nanometers. Broadband ultrashort pulses from about 500 nm to 1020 nm are obtained seeding with a light beam at around 900 nm with 9 nm full spectral bandwidth. The temporal and spatial parameters of the generated broadband pulses are measured and analyzed. A new method for the generation of wavelength tunable broadband ultrashort lights is presented. The broadband light beam generation phenomenon can be explained by ping-pong four wave mixing (PPFWM) process, which helps us to understand all the optical parametric processes visually. The generated broadband pulses have potential applications in ultrafast spectroscopy and ultrafast pump–probe experiments.

In this work, we report the use of V2C-deposited SPF as a nonlinear device for the generation of four-wave mixing (FWM) effect in 1.5- and 2.0-µm wavelength operation. The FWM-based system was able to generate idlers at 1.5- and 2.0-µm with a peak conversion efficiency of –44 dB and –41 dB and had a maximum tuning range of 5.5 nm and 12 nm respectively. The nonlinear optical properties of V2C MXene were studied by Z-scan analysis, where V2C had a nonlinear absorption coefficient, β and nonlinear refractive index, n2 of (5.95 ± 5.18) × 10-8 m/W and (-2.43 ± 4.93) × 10-20 m2/W. The experimental results demonstrated that V2C-deposited SPF was effectively employed as a nonlinear device to induce the FWM effect.

We experimentally study intracavity four-wave mixing (FWM) using Λ -type, three-level electromagnetically induced transparency (EIT) atoms confined in an optical ring cavity. The original dark-state peak disappears accompanying the generation of intracavity FWM when the coupling light is changed from traveling-wave to standing wave. Additionally, this FWM signal is on resonance with the optical cavity only when the coupling laser is detuned from the atomic resonance center, where the absorption is drastically reduced for both the probe and FWM fields. At last, we do theoretically analysis for the susceptibility of this composite atom–cavity system.

We theoretically propose a hybrid scheme with nonlinear four-wave mixing process and linear beam splitters to generate continuous-variable quadripartite entanglement. To expose the entanglement properties of the generated state, the coupling strength matrix is derived to reveal the interactions of the resulting modes at first. The generated state is verified to be a H -graph state with a non-full rank coupling strength matrix by using graphical calculus for Gaussian pure states. Then based on the eigenmodes for the generated state, we find that the introduction of beam splitters does not alter the deduced eigenmodes of the nonlinear four-wave mixing process, and only contributes to generate quadripartite entanglement. In the end, we quantitatively investigate the internal entanglement structure of this scheme. Our work paves the way to generate quadripartite entanglement from a hybrid scheme with nonlinear four-wave mixing process and linear beam splitters.

In this work, stable multiwavelength thulium laser (TDFL) using interleaving filter and assisted by four wave mixing (FWM) effect in 0.5 km long highly nonlinear fiber (HNLF) is experimentally demonstrated. The impacts of altering the thulium pump power and wavelength on several laser characteristics such as threshold, laser count, output power and optical signal to noise ratio are investigated. Up to 19 output wavelengths within a 10 dB bandwidth with optical signal-to-noise ratio of more than 35 dB were generated from 1875 nm to 1897 nm. The laser has a threshold pump power of 0.3 W and a maximum peak power and wavelength fluctuations within 60 min of 1 dB and 0.2 nm respectively, which indicates the good stability of the proposed fiber laser. The laser performance without HNLF emphasizes the significant role of FWM in the performance of TDFL in terms of stability and number of wavelengths.

We experimentally demonstrate all-optical phase-sensitive quantization of a 10–20 Gbaud quadrature phase-shift keying (QPSK) signal’s phase without an active phase-locked loop (PLL) by utilizing Brillouin amplification (BA) to amplify the fourth-harmonic idler without path separation, allowing the pump, signal, third-harmonic idler and amplified fourth-harmonic idler to remain synchronized in the phase. We observe up to 65% reduction in phase noise and 4.6 dB gain at a bit-error rate (BER) of 1 0 − 4 over 36 min of continues operation.

The conditions under which losses can be compensated in the case of propagation of an backward signal wave under parametric four-wave interaction are analyzed. It is shown that, in the presence of a parametric coupling between forward and backward waves, compensation of signal wave losses by losses of direct waves will allow the parametric amplification and generation of the backward wave to be realized at the threshold pump amplitude. An analytical expression is obtained for the threshold pumping amplitude under phase-matching conditions. It is shown that the threshold pump amplitude increases with increasing losses, the input intensity of the idler wave, and with increasing nonlinear coupling coefficients for pump waves. As a consequence, it is possible to control the threshold pump intensity. and it is possible to obtain significant amplification in the metamaterial, as well as parametric generation of the backward wave.

Bi-directional light propagation is expected to enable enhanced functionality of all-optical signal processing operations compared to unidirectional approaches. In this work, we report on compensation of slow gain recovery in semiconductor optical amplifiers (SOAs) in a double-pass condition. The unsaturated gain of the employed SOA is increased by 12.6 dB, and the corresponding normalized conjugate output of four-wave mixing is enhanced by 16.3 dB. The theory attributes this efficiency improvement to the unsaturated gain enlargement which, in turn, compensates for the inherently long carrier lifetimes of SOAs by 50%. The saturation output power remains virtually unchanged.

Optical solitons in birefringent fibers with the effect of four-wave mixing having both parabolic and Kerr law nonlinearity are obtained by the modified simple equation scheme and the trial equation approach. Dark, bright as well as singular soliton type solutions are derived. Also, the two integration schemes give rise to additional solutions such as singular periodic solutions.

This paper studies optical solitons in birefringent fibers with parabolic law nonlinearity coupled with waekly non-local nonlinear medium. The four-wave mixing effect is taken into consideration and thus retrieval of soliton solutions would require phase-matching condition.

The four-wave mixing (FWM) effect of a weak probe field, in an asymmetric semiconductor double quantum dot (QD) structure driven by a strong pump field is theoretically studied. Similarly to the case of examining several other nonlinear optical processes, the nonlinear differential equations of the density matrix elements are used, under the rotating wave approximation. By suitably tuning the intensity and the frequency of the pump field as well as by changing the value of the applied bias voltage, a procedure used to properly adjust the electron tunneling coupling, we control the FWM in the same way as several other nonlinear optical processes of the system. While in the weak electron tunneling regime, the impact of the pump field intensity on the FWM is proven to be of crucial importance, for even higher rates of the electron tunneling it is evident that the intensity of the pump field has only a slight impact on the form of the FWM spectrum. The number of the spectral peaks, depends on the relation between specific parameters of the system.

The solitons dynamics induced by more practical and complex forms of modulation instability (MI) have still not been revealed. In this paper, the solitons dynamics induced by MI with randomly perturbed initial conditions are observed experimentally. The mark of the MI development from linear stage to nonlinear development stage is the appearance of particular classes of super-regular breathers with bipolar complex oscillation structure. The interaction of the multiple sets of opposite quasi-degenerate four wave mixing processes can be treated as a sort of “turbulence” appearing as a result of nonlinear development of MI. Our results open up possibilities to explore the MI that develops from some kind of arbitrary perturbed background.

In today’s world, data rate and bandwidth are the two most important considerations while designing any communication systems. Optical fiber communication is one such system that can offer data rate and bandwidth of the order of few terahertz with the use of wavelength division multiplexing in which several wavelengths can be sent over the same fiber simultaneously without interference. In case of wavelength division multiplexing based optical network, routing and wavelength assignment schemes are used to establish light wavelengths or ligthpaths between source and destination nodes for efficient utilization and allocation of available wavelength spectrum with minimum adjacent channel interference. However, nonlinearities such as four wave mixing cause interaction of different lightpaths while transmission which degrades the performance of the network in terms of bit error rate and signal-to-noise ratio. In this paper, novel wavelength assignment scheme is proposed to mitigate effect of four wave mixing which is further utilized to enhance data rate of fiber.

We investigate diverse optical solitons and other solution for the Coupled Nonlinear Schrodinger Equation (CNLSE) having Four-Wave Mixing (FWM) and Kerr nonlinearity term. We stress the effects of different parameters of the model on the obtained optical soliton by employing the New Generalized Extended Direct Algebraic Method (NGEDAM). The solutions contain W-shaped profile of the bright optical soliton, dark optical soliton and diverse other solutions including the combined complex optical soliton. Interestingly, W-shaped optical soliton and dark optical soliton own a good argument for long communication and big data transmission originating from the self-steepening, Kerr nonlinearity effects and FWM. We also, emphasize the Modulation Instability (MI) gain spectra to narrow the impact of the FWM in birefringence. Thereafter, we involve the ellipticity angle effects in normal and anomalous dispersion regime on the MI gain spectra. Parametric conditions for the existence of the obtained optical soliton solutions and MI gain are given.

The present work shows the role of nonlinear saturation effects on modulational instability (MI) in a birefringent media with the help of nonlinear wave propagation technique. Using the Kundu–Eckhaus (KE) equation, we investigate both self phase and cross phase modulation effect on MI in a birefringent media without four wave mixing term. We consider only KE equation model without the existence of four wave mixing expression and the standard linear stability theory is presented to the appropriate model. In the case of modified KE equation, we discuss the role of MI in a birefringent fiber system with the help of conventional type of saturation effect. In the case of KE without four wave mixing, we observed that the SPM plays a vital role on MI in coupled birefringent fiber compared to XPM as shown in Ref. Parasuraman (2021). But, In saturable KE has different MI characteristic as well as growth rate of profile in birefringent model with the help of particular emphasis values of the nonlinear parameters. However, the nonlinear saturation KE model more helps to generate soliton or solitary wave in coupled nonlinear birefringent fiber in the presence of both SPM and XPM.

A detailed investigation of the performance of four-wave mixing (FWM) in non-flared- and flared-waveguide semiconductor optical amplifiers (FW-SOAs) has been reported. A standard rate equation model has been used which considers the effect of the distribution of carrier density of the transverse direction based on numerical calculation along with the nonlinear Schrodinger equation (NSE). The results have been reported in saturated and unsaturated states of the FW-SOAs. Features of the FWM pulse, such as peak pulse deviation, pulse width, and pulse energy along the length of the SOA cavity have been studied and compared in detail for three waveguide geometrics (non-flared, linearly flared, and exponentially flared). Evolution in time and spectral domain of the FWM pulse has been shown for three different structures. It has been found that the FW-SOAs perform better under saturated regime since the FWM pulse has less distortion compared to the non-flared SOA. In an FW-SOA, pulse-width variations of the FWM pulse are almost insignificant whereas in the non-flared SOA, the FWM pulse suffers from broadening.

This paper investigated the effect of FWM and its suppression using optical phase conjugation modules in dispersion managed hybrid WDM-OTDM multicast overlay system. Interaction between propagating wavelength signals at higher power level causes new FWM component generation that can significant limit the system performance. OPC module consists of the pump signal and 0.6 km HNLF implemented in midway of optical link to generate destructive phase FWM components. Investigation revealed that by use of even OPC module in optical link reduces the FWM power and mitigate the interaction between wavelength signals at variable signal input power, dispersion parameter ( β 2 ) and transmission distance. System performance comparison is also made between without DM-OPC module, with DM and with DM-OPC module in scenario of FWM tolerance. The BER performance of hybrid WDM-OTDM multicast system using OPC module is improved by multiplication factor of 2 as comparable to dispersion managed and coverage distance is increased by factor of 2 as in Singh and Singh (2016).

We propose a novel candidate wavelength plan for suppressing four-wave mixing (FWM) in 100G-EPON. Advanced simulation using VPI is performed to analyze the FWM induced system distortion. Simulation results indicate that the proposed wavelength plan shows significant advantage in FWM suppression. Besides, an 8-channel wavelength plan is also proposed as an upgrade path to 200G-EPON.

We study the modulational instability of nonlinear wave propagation in birefringent fiber of the Kundu–Eckhaus equation without four wave mixing term and analysis the effect of self phase modulation and cross phase modulation. The model of Kundu–Eckhaus equation in the absence of four wave mixing term are consider and apply the linear stability analysis to the Kundu–Eckhaus equation. Modulational instability criteria are found from linearized equations for small perturbations. Using modulational instability criteria, the self phase modulation and cross phase modulation effects on optical wave propagation in birefringent fiber are discussed.

The dark soliton propagation in birefringent fiber of Kundu–Eckhaus equation with four wave mixing and inter-modal dispersion is investigated. We consider the Kundu–Eckhaus (KE) equation with the inclusion of four wave mixing term and inter-modal dispersion term. The developed Jacobi elliptic function expansion method is used to construct the solution of KE equation. New results are presented which includes dark soliton solution and using it to analysis the inter-model dispersion in birefringent fiber of the KE equation with four wave mixing.

We demonstrate a broad and flat optical frequency comb (OFC) by exploiting the four-wave mixing experienced by optical signals propagating through the highly nonlinear fiber. We modulate two 50 GHz spaced continuous wave laser signals using single mach-zehnder modulator controlled by 25 GHz periodic radiofrequency signal which results in a broad but non flat and non-coherent OFC. 400 m long highly nonlinear fiber (HNLF) is used to initialize the four wave mixing and induce the coherency between the OFC frequency lines. The flatness and broadness of optical frequency comb further enhanced by passing it through a 500 m long fiber. By managing a highly nonlinear fiber length compared to the coherence length, nonlinear coefficient, and injected optical power inside two-stage cascaded erbium-doped fiber amplifier (EDFA) and HNLF, an optical frequency comb of 55 frequency lines with 3 dB maximum power deviation is realized.

The four wave mixing (FWM) characteristics of highly nonlinear tellurite photonic crystal fiber are simulated. The material of tellurite fiber is TeO2-Li2O-ZnO-P2O5 (TLZP). It is calculated that there are two zero dispersion points at 1590 nm and 3880 nm in tellurite photonic crystal fiber. The linear phase mismatch, the variation of optical signal gain with fiber length and the pump power are calculated at 1538 nm and 3865 nm respectively. The results show that the fiber has good four wave mixing performance near 1550 nm communication window and mid infrared region.

We propose a scheme for all optical wavelength conversion (AOWC) of dual users coherent optical orthogonal frequency division multiplexing (CO-OFDM) system with error bits free. The scheme is based on four wave mixing (FWM) in high nonlinear fiber (HNLF). In this scheme, cascade HNLFs are used to generate twice FWM processes. The simulation results show that the wavelength converted signal can be obtained successfully. Optical spectra and constellation diagrams of the proposed wavelength conversion (WC) system indicate a better error tolerance and resistance to phase noise compared with that of a system without WC. The bit error rate (BER), error vector magnitude (EVM), and optical signal-to-noise ratio (OSNR) penalty of the CO-OFDM system with AOWC are analyzed. The proposed scheme is also validated after the optical fiber transmission and in single user CO-OFDM systems based on BER performance and constellation diagrams, respectively.