Performance Analysis of XPM Nonlinear effects on WDM Link

Transcription

1 Performance Analysis of XPM Nonlinear effects on WDM Link Surajmukhi*, Manju**, Kuldeep Singh*** *(Department of Electronics and communication, Guru Jambheshwar University, Hisar) ** (Department of Electronics and communication, Guru Jambheshwar University, Hisar) ***(Assistant Professor,Department of Electronics and communication, Guru Jambheshwar University, Hisar) ABSTRACT In this paper, a simulation model with NRZ modulation for reducing the nonlinearity has been proposed by use of different parameter like length, power and dispersion. Firstly, we evaluate the effect of XPM nonlinearity on the output spectrum. The simulated results show that the fiber link with a distance of approximately 120 km at transmitted power of 10 mw may be designed with value of Q factor and BER is quite above the threshold level. The performance of four channels on WDM has been evaluated in terms of Q-factor, BER against power, dispersion and length to study the nonlinear effects. The main reason of nonlinear effects are change in inelastic scattering and refractive index of the fiber The performance of designed Cross phase modulation has been executed for evaluation in terms of BER, Q factor and eye diagrams.these effects are analyzed with OPTSIM tool. It has investigated that fiber having the distance of 40 km at the power10and dispersion 1.5 ps/nm/km the value of quality factor is found to be [dB], [lin]. Keywords-BER, Q-Factor, SPM, XPM. 1 INTRODUCTION It is an investigated that fiber optical technology is good to fulfill the user requirement for more bandwidth and high data rate with minimum losses. More bandwidth and high data rate are used in WDM and different applications.the optical power should be large to overcome power penalty effects to obtained good design goal. It is better when fiber is linear. But in actually fiber nonlinear effects occur when power increases. These nonlinear effects are intensity and power depended. When the power level increases above 10 mw different type of nonlinearity comes.it is necessary to study these effects for improve the performance of any system. It occurs due to change the refractive index of medium with intensity. The nonlinear effects are in optical fiber are SPM XPM FWM For electromagnetic fields, any dielectric medium act as nonlinear medium. The origin of nonlinearity lies in a harmonicmotion of bound electrons under the influence of an applied electric field. The total polarization P induced by electric dipoles is not linear. P =ε 0 χ (1) E+ ε 0 χ (2) E 2 + ε 0 χ (3) E 3 +. [1] Whereε 0 is the permittivity of vacuum andχ (k) is k th order susceptibility. The dominant contribution is provided by linear susceptibility. The second order susceptibility is responsibility is responsible for second order harmonic generation. The third order susceptibility is responsible for lowest order nonlinear effects. When no of channel are very large in WDM then each channel effected by rest of channel in 128 WDM channel.each channel carry 2-3 mw power. So effect of XPM are strong on WDM each channel carry small power. XPM cause pulse broadening which is not symmetric. The non-linearity in refractive index is known as Kerr nonlinearity [2]. These nonlinearity induces the phase modulation of modulation of propagating of signal isknown as Kerr effects. In single wavelength called SPM and in multiple wavelengths called XPM. 74 Surajmukhi, Manju, Kuldeep Singh

2 1.1Cross phase modulation Cross phase modulation is a nonlinear effect where one wavelength of light can affect the phase of another wavelength of light. When the optical power from a wavelength impacts the refractive index, the effect of new refractive index on another wavelength is known is XPM. It causes change the phase of signal and pulse broadening. Soto reduce the nonlinearity effects we use a fiber that has some dispersion. [2] 2EXPEIMENTSETUP The experiment consist of blocks, and a scope in output to measure the BER,Q factor and to plot the eyediagrams.the simulation setup with centre frequency HZ for first channel, for the second channel, for the third channel and for the last channel simulated XPM optical link by using NRZ modulation format.in optical link fixed gain output amplifier has been added to remove the losses that occur during transmission of data. Figure 1 block diagram of 4 channel Cross phase modulation 3 Simulation work We simulate the XPM by varying dispersion, length and power. By using these we can mitigate and overcome the nonlinear effects. In this simulation model we use the frequency of first 3.1 XPM analysis and results It defines the input spectrum of input signal and the frequency of signal which is to be transmitted. The measurement component used for this optical Spectrum Analyzer. channel and of 2 nd channel of third and for the fourth channel. We investigate that by using the optical match filter good results are obtained instaed of using the Besselfilter. 75 Surajmukhi, Manju, Kuldeep Singh Figure 3 input spectrum

3 It definestheoutput spectrum of input signal after passing through the fiber. But due to XPM nonlinearity the 4channel spectrum becomes broad appear like as shown in fig (1.7). Figure 4 output spectrum It shows the quality of signal which is received at the receiver. The value of quality factor should be above 16 in case of db and above the 6 in case of linear scale. Figure 6 BER Versus dispersion Q-factor shows the quality of signal which is received at the receiver. The value of quality factor should be above 16 in case of db and above the 6 in case of linear scale. Figure 5 Q Factor Versus Dispersion(0,2, ps/nm/km) The value of BER will be decrease with increase in dispersion.it should be below 10 9 to achieve good performance. Figure 7 Quality Factor Versus length(50,60,70,80,90 and 100) 76 Surajmukhi, Manju, Kuldeep Singh

4 BER defines as the no of errors to the total no of bi transmitted.the value of BER will be decrease with increase in dispersion. It should be below 10 9 to achieve good performance. Figure 8 BER versus length An eye diagram defines the quality of signal to be transmitted or defines the quality ofsignal receivedat the output. We will take these eye diagrams by using electrical scope. Figure 10 Eye Diagram at dispersion(10nm/ps/km),length(50km) Figure 9 Eye diagram at dispersion(8nm/ps/km),length(50km),power(10mw) Figure10 Eye Diagram at dispersion(16nm/ps/km),length(90km) 77 Surajmukhi, Manju, Kuldeep Singh

5 the quality factor is [lin], Db. The value of BER are e-024 is found to be at length 120, power 12mw and the dispersion ps/nm/km. Figure 11 Eye Diagram at dispersion(17nm/ps/km),length(100km) 4 CONCLUSION The result have obtained for WDM system using NRZ modulation format with narrow channel spacing to evaluate the performane in terms 0f Q factor, BER and eye diagrams.four different frequency ( , , and ) have been taken foe evolution of WDM in terms of BER, Q factor and eyediagrams.the sysyem with NRZ modulation format shows good result up to 120 km distance for optical fiber communication. At distance of 150 km BER is very high and quality factor is not so good. At frquency , , and the value of 5 REFERENCES [1] S.P. Singh and N. Singh,Nonlinear effects in optical fiber ORIGIN, MANAGEMENT AND APPLICATIONS(2007). [2] Agarwal, G.P,Nonlinearity Fiber optics, 3 rd edition, Academic press, San Diego, CA, (2001). [3] Manjit Singh, Ajay.K.Sharma, R.S.Kaler,Investigations on optical timing jitter in dispersion managed higher order soliton System(2011). [4] Gousia, G.M.Rather, Ajay.K.Sharma, WDM- OTDM based spectral efficient hybrid multiplexing technique inherent with properties of bandwidth elasticity and scalability (2010). [5] Ajay.K. Sharma, S.K. Wadhwa, T.S. Kamal,Robustness of NRZ, RZ, CSRZ and CRZ modulation on fiber nonlinearities and amplifier noise at 40 Gbps for (OC-786) long haul link (2008). [6] Manjit Singh, Ajay.K.Sharma, R.S. Kaler, Manoj Kumar, Timing jitter dependence on data format for ideal dispersion compensated 10 Gbps optical communication system (2007). [7]VishalSharma, Amarpal Singh, Ajay.K.Sharma, Analysis and simulation of the effect of spectral width over intensity noise under the impact of higher order dispersion parameters in the optical communication systems(2008). [8] N Rauter and R Lammering, Numerical simulation of elastic wave propagation isotropic media considering material and geometrical nonlinearities (2015). 78 Surajmukhi, Manju, Kuldeep Singh