Impact Of Self-phase Modulation Research Articles

Quadruple impact of SPM, XPM, FWM and SRS nonlinear impairments on the performance of DWDM-PON

Recently, dense wavelength division multiplexing passive optical networks (DWDM-PONs) have become a considerable choice for 5G and beyond fronthaul implementations. Formerly, we have proposed a full-duplex bidirectional DWDM-PON architecture convenient for those implementations and analyzed the combined dual impact of four-wave mixing (FWM) and stimulated Raman scattering (SRS) nonlinear impairments on the proposed architecture. Meanwhile, a detailed literature analysis showed us that the combined quadruple impact of self phase modulation (SPM), cross phase modulation (XPM), FWM and SRS on the performance of bidirectional DWDM-PONs have never been researched up to now. In this paper, quadruple impact of SPM, XPM, FWM and SRS on the performance of both uplink channels (ULCs) and downlink channels (DLCs) of the formerly proposed DWDM-PON has been analyzed with simulations. Simulations have been performed in O-band region for ULCs and in C-band region for DLCs of 2 × 15- and 2 × 63-channel DWDM-PONs having 12.5 GHz, 25 GHz, 50 GHz, 100 GHz equally-spaced channels. The quadruple impact of optical nonlinear impairments on the DWDM-PON performance has been analyzed with signal-to-crosstalk ratio (SXR) simulations performed under varying channel input powers and channel lengths. Results show that under the quadruple nonlinear impact reliable bidirectional transmission with an SXR over 23 dB can be achieved for channel input powers below 0.58 mW and 0.16 mW in 2 × 15- and 2 × 63-channel DWDM-PONs, respectively, for all channel spacing values and 25 km transmission lengths. Moreover, results also imply that variations in channel lengths do not significantly affect SXR at both ULCs and DLCs of 2 × 15- and 2 × 63-channel DWDM-PONs for lengths exceeding 50 km. The thorough analysis presented in the paper will give a new insight for analysis of conventional and next generation PONs.

Impairment strained analytical modeling evaluation and cross-talk analysis of symmetric and coexistent channels for extended class-1 NG-PON2 access network.

The analytical modeling for linear and non-linear impairments (LNI) for single mode fiber (SMF) and simulative analysis of extended power budget class-1 i.e. E1-class of next generation passive optic network-2 (NG-PON2) is presented in the paper. The proposed power-budget class time and wavelength division multiplexing (TWDM) based NG-PON2 network configuration is delivering symmetric 2.5 point-to-multi point (PtM) representing time and TWDM XGS-PON along with 10 Gbps point-to-point (PtP) wavelength division multiplexing (WDM) symmetric and coexistent channels (Ch) in worst-case scenario. Channel modelling of LNI is carried out under the incremental and aggregate strain of estimated chromatic dispersion CD, self-phase modulation (SPM), cross-phase modulation (XPM) of single mode fiber (SMF) channel deployed in optical distributing network (ODN) between 20 and 50 km link lengths. Downlink (D/L) and uplink (U/L) ODN is optimized to PTODN = 7.1 dBm and 4.09 dBm, respectively and corresponding channel imparities including Kerr parameter γ, corresponding SPM, XPM, CD, four-wave mixing (FWM) analysis and corresponding component power and efficiency, interchange crosstalk (Cc) attracting power penalties (Pc) are estimated and incorporated in the simulation for the real response of lossy SMF channel. Further, splitter power budget (SP) and slitter configuration for respective PtM and PtP D/L Ch are estimated under the aggregate impact of CD, SPM, XPM and FWM. Analytical modeling of LNI and simulative analysis has confirmed the configuration delivered rise in receiver sensitivity (Rxs) of − 39.75/− 33.45 dBm and − 29/− 35.34 dBm for D/L and U/L Ch respectively. The estimated power of FWM element is between 1.34 × 10−52 to 2.15 × 10−53 and 3.87 × 10−52 to 2.41 × 10−51 contributing crosstalk between Ch (Cc) of − 31.97/− 30.12 dB for down/up spectrum under the impact of SPM and XPM respectively accommodating splitter configuration of 768 at 40 km.

A Novel Scheme for Orthogonal Frequency Division Multiplexing-Radio over Fiber Based on Modulator and Dithering Technique: Impact of Self Phase Modulation and Group Velocity Dispersion

Nonlinearity characteristic in OFDM (Orthogonal Frequency Division Multiplexing)-RoF (Radio over Fiber) system which causes the frequency shift of light and has a high electrical field on medium transmission. We begin by discussing SPM (Self Phase Modulation) and GVD (Group Velocity Dispersion) are part of nonlinear characteristic. SPM induced spectral broadening will be degrade performance of light wave and GVD will be impact on duration pulse of optic. The impaired information signal reduces the power and later affects the quality of signal. This research aims to focus on the improvement of two external modulator LiNbO3 MZM (Lithium Niobate-Mach Zehnder Modulator) and applying of frequency dithering techniques to reduce the existing nonlinearity of the optical fiber purposely to enhance the receiving power for the lower input power with the length of fiber up to 100 km. Finally, the result shows an average of 18.5% increase in the power level for linewidth of 1 MHz, 3 MHz, and 7 MHz across 50 km distance with the log BER (Bit Error Rate) -2.407, BER 0.003, and SNR (Signal to Noise Ratio) 43.8, across 100 km of optical fiber the value of log BER -2.471, BER 0.003, and SNR 49.14.

Influence of temporal–spectral effects on ultrafast fiber coherent polarization beam combining system

The active coherent polarization beam combining (CPBC) technique has been experimentally proved to be a promising approach for the energy and power scaling of ultrashort laser pulses, despite the tremendous challenge in temporal synchronization, dispersion management and nonlinearity control. In order to develop a comprehensive theoretical model to investigate the influence of temporal–spectral effects on ultrafast fiber active CPBC systems, a generalized nonlinear Schrödinger equation carrying spectral factors is used to depict the propagation of ultrashort pulses in fiber amplifier channels and ultrashort-pulsed Gaussian beams (PGBs) carrying temporal–spatial factors are utilized to picture the propagation of ultrashort pulses in the free space. To the best of our knowledge, the influence of different temporal–spectral effects has been segregated for the first time and corresponding analytical equations have been strictly derived to link the combining efficiency with specific factors. Based on our analysis, the optical path difference (OPD) has the most detrimental impact on the combining efficiency because of the high controlling accuracy and anti-interference requirements. For instance, the OPD must be controlled in ~ ±14 μm to achieve a combining efficiency of above 95% for combining ultrashort laser pulses with a 3 dB spectral bandwidth of 13 nm centered at 1064 nm. Besides, the analytical expression also demonstrates that the impact of self-phase modulation on the combining efficiency has no dependence on spectral bandwidth and only depends on the B integral difference if neglecting the direct influence of the peak power difference. Our analysis also indicates that the group velocity dispersion has relatively small influence on the combining efficiency. These formulas can be used to diagnose the influence of temporal–spectral effects and provide useful guidelines for the design or optimization of the active CPBC system of ultrafast fiber chirped-pulse amplifiers.

Impact of Self-Phase Modulation on Instabilities in Fiber Lasers

Continuously pumped Yb-doped double-clad fiber lasers exhibit two kinds of instabilities, known as self-sustained pulsing and self-mode locking (SML). We study numerically the role of self-phase modulation (SPM) on the onset of these stabilities by using a spatiotemporal model that takes into account fully the length dependence of both the optical gain and spontaneous emission, while also including the nonlinear effects within the fiber. Self-sustained pulsations originate from relaxation oscillations. Although they die out quickly in the absence of SPM, our results show that SPM restores these oscillations when the laser power exceeds a certain value. SML has its origin in the spontaneous-emission noise acting as a seed. The laser cavity amplifies this noise the most at frequencies associated with its longitudinal modes, resulting in periodic power variations with an amplitude <; 1% (without SPM). We find that SPM plays again a critical role and increases their amplitude to above the 10% level. We also show that the SPM-induced instabilities can be suppressed by inserting a passive fiber of suitable length inside the laser cavity, which is in agreement with recent experimental work.

Impact of self-phase modulation on coherently combined fiber chirped-pulse amplifiers

The impact of self-phase modulation on coherently combined ultrafast fiber-based chirped-pulse amplifiers (CPA) is studied. We point out that, in nonlinear CPA regime, the nonlinear phase accumulated in each fiber amplifier can significantly differ from one to another, resulting in serious efficiency degradation of coherent combining. A test bench based on picosecond pulses, and a single fiber amplifier is developed to experimentally demonstrate the effect. The effects that can lead to this nonlinear phase deviation and the induced system limitations are discussed and analyzed.

High-Energy, Short-Pulse Fiber Injection Lasers at Lawrence Livermore National Laboratory

A short-pulse fiber injection laser for the advanced radiographic capability on the National Ignition Facility has been developed at Lawrence Livermore National Laboratory. This system produces 100 ?J pulses with 5 nm of bandwidth centered at 1053 nm. The pulses are stretched to 2.5 ns, and have been recompressed to subpicoseconds pulsewidths. A key feature of the system is that the prepulse power contrast ratio exceeds 80 dB. The system can also precisely adjust the final recompressed pulsewidth and timing, and has been designed for reliable, hands-free operation. The key challenges in constructing this system were control of the SNR, dispersion management, and managing the impact of self-phase modulation on the chirped pulse.

Impact of Self-Phase Modulation on In-Band Crosstalk Penalties

We investigate the performance of a signal impaired by in-band crosstalk, when the shape of the crosstalk signal is distorted. The optical signal-to-noise ratio (OSNR) penalty increases up to 0.5 dB comparing cases with and without distortion due to self-phase modulation in the crosstalk signal. Furthermore, the OSNR penalty significantly depends on the accumulated dispersion of the considered dispersion map of the crosstalk signal. If optimum accumulated dispersion is considered for the crosstalk signal, the crosstalk-induced penalties are higher than expected.

Impact of fiber nonlinearity on PMD penalty in DWDM transmission systems

Polarization-mode dispersion (PMD) penalty measurement on a 10-Gb/s deployment-ready dense wavelength-division-multiplexing (DWDM) long-haul transmission system is reported in this letter. We investigate the impact of self-phase modulation (SPM) and cross-phase modulation (XPM) on PMD penalty in the DWDM system. It is confirmed that SPM can suppress the PMD penalty, and XPM-induced polarization-scattering in DWDM systems can reduce the PMD impairment a little bit further. Our measurements suggest that it is necessary to carry out the PMD penalty test on DWDM systems rather than back-to-back systems in order to accurately allocate transmission margin of the systems.

Impact of Self-phase Modulation on Optical Direct Detection CPFSK Transmission System

A detailed theoretical analysis is presented to evaluate the combined influence of self-phase modulation (SPM) and group velocity dispersion (GVD) of optical fiber on the bit error rate (BER) performance of a direct detection optical CPFSK system. Performance results are evaluated at a bit rate of 10 Gbit/s taking into considerations the random phase fluctuations at the receiver output due to GVD and SPM. The power penalty suffered by the system due to combined influence of GVD and SPM is then determined at a BER of 10 -9 , The results show that the performance of optical direct detection CPFSK is highly degraded due to SPM at input power of more than 5 dBm and the penalty is minimum at a modulation index of 0.5.

243 km, 10 Gbit/s transmission experiment throughstandard fibre and impact of self-phase modulation using partial response scheme

The authors demonstrate optical transmissions at 10 Gbit/s on standard dispersive fibre using a partial response scheme. Investigations have been carried out concerning the optimum launched power into a 142 km long repeaterless link in order to quantify the effects of self-phase modulation. According to these results, 243 km of standard fibre, totalling a dispersion of 4500 ps/nm, has been bridged without any dispersion compensating device.