Effect of Stimulated Raman Scattering (SRS) in WDM system using OptiSystem

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056

Volume: 09 Issue: 12 | Dec 2022 www.irjet.net p-ISSN: 2395-0072

Effect of Stimulated Raman Scattering (SRS) in WDM system using OptiSystem

1 Department of Electrical Engineering, Maharashtra, India

2 Head of Department of Electrical Engineering, Veermata Jijabai Technological Institute, Maharashtra, India ***

Abstract - Stimulated Raman Scattering (SRS) is one of the most important optical fiber techniques that is used extensively in manyscientific fieldsthatcanturnopticalfibers into broadband Raman amplifiers and tunable Raman lasers. SRS is one of the fundamental nonlinear effects occurs in the optical communication, until recently it was observed as a harmful nonlinear effect because it transfers energy from one channeltoneighboringchannelwhichlimitstheperformance of multichannel lightwave system. With the help of optiwave simulation software we are going to build the schematics of the WDM (Wavelength Division Multiplexing) system and by adding the SRS effect, we are going to analyze the results. We are going to analyze the results by varying the power parameter at the input side. So, we observed that at the receiving end the results we get are distorted, due to the existence of the SRS effect in system. we observe that the power gets transfer from one signal to another and after varying the power they get multiplied gradually, can be observed in this paper. This study will help to understand the optiwave software and the effect of SRS on optical communication.

Key Words: Stimulated Raman Scattering (SRS), WDM (Wavelength Division Multiplexing), optiwave, nonlinear effects,opticalfibercommunication,Ramantilt.

1. INTRODUCTION

Optical signals are largely affected when light waves transmitted through optical fiber interacts with the materialstransmittingthemthanwitheachother.Thisresult in nonlinear effects, the strength of which dependson the square(orsomehigherpower)ratherthanjusttheamount of light present. With the help of wavelength-division multiplexing(WDM)weareableusethehugebandwidthof theopticalfibreduetowhichithasdrawnalotofattention inbroadbandopticalnetworksandwirelesscommunication. Butwhenseveralopticalsignalsaremultiplexed,coupling and crosstalk between the multiplexed signals occur as a result of various fibre nonlinear effects, and these phenomena ultimately restrict the performance of WDM networks.Furthermore,opticalfibresaretheonlymaterials withaparticularlylowthresholdfornonlineareffects.Under therightcircumstances,theseinteractionsinWDMproduce new waves through a number of non-linear processes, including Stimulated Raman Scattering (SRS), Self-Phase

Modulation (SPM), Four Wave Mixing (FWM), and CrossPhase Modulation (CPM). In a WDM system, these effects limit the maximum power per channel, the maximum bit rate, and the system's optimal efficiency. They also set restrictions on the distance between neighboring wavelengthchannels.Nonlinearityinopticsisanintensity dependent phenomenon which occurs due to change in therefractiveindexofthemediumwithopticalintensityand inelasticscatteringphenomenon.

TheKerr-effectiscausedbytherefractiveindex's powerdependence.Theinelasticscatteringphenomenacan producestimulatedeffectslikeStimulatedRamanScattering at high power levels (SRS). Particularly in wavelengthdivisionmultiplexing(WDM)systems,theseinteractionscan beasignificantdrawbackinopticalcommunications.Finding outputsignalswithnearlythesamequalityandquantityas theinputsignalmaybepossiblewiththehelpofresearchon non-linearitiesinopticalfibre.Butit'sadifficultundertaking tostudyopticalfibrecommunicationnetworksbecauseof thecomplexinteractionsbetweentheimpairments.

TheRamaneffect, whichRamanfirstidentifiedin 1928,canbedefinedquantummechanicallyasthescattering by a photon of energy hωp by a moleculeto alower frequencyphotonwithenergyhωsasthemoleculechanges to a vibrational state (see fig. 1). The high-energy photon thatisalsotheincidentlightbehavesasapump,generating frequency-shiftedradiation.Theenergyreleasedbytheatom followingthecollisionofthelow-energyscatteredphotonsis knownastheStokeswave.Theenergyofstokeswaveisless becausetheatomabsorbedtheenergy.Somewavecalledas Anti-stokesarealsogenerated,whichhasenergyhigherthan thepumpstokeshωaandhavehighamplitude.Itwasfound in1962thatintensepumpfieldscanleadtothenonlinear phenomenaofSRS,inwhichtheStokeswavegrowsquickly withinthemediumandthemajorityofthepumpenergyis transferredtoit.Sincethen,awiderangeofmolecularmedia havebeenusedtostudySRSextensively.Theopticalfibres can be converted into broadband Raman amplifiers and adjustable Raman lasers using SRS. In any molecular medium,itcanalsosignificantlyreducetheperformanceof multichannellightwavesystemsbytransferringenergyfrom one channel to neighboring channels (see fig. 2). A tiny fraction of power (usually ∼10−6) can be transferred by spontaneous Raman scattering from one optical field to

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056

Volume: 09 Issue: 12 | Dec 2022 www.irjet.net p-ISSN: 2395-0072

another, whose frequency is downshifted by an amount definedbythemedium'svibrationalmodes.

In this research, our main interest is the study of Stimulated Raman-Scattering (SRS) on fibre optic communicationsystems.Therearemanydifferentkindsof simulatorsthatcanbeusedtostudytheSRSphenomenon, butwechosethemostpowerfulone,calledOptiSystem,to evaluateandsimulateopticalfibrenetworksandtechniques. Thissimulatorhasproventobeeffectiveinmanyareasof planning, testing, and the advancement of optical networking,andithashelpedOptiwaveexpanditsfeatures andfunctionality.

thesameconfigurationasCWlaserarrayisgivenintothe Non-linearopticalfiber.

Figure1SRStransferopticalpowerfromshorter

Figure3ExperimentsetupforSRS

IntheNonlinearopticalfiber,weneedtoenablethe RamanscatteringparametertoaddtheSRSeffectandallthe parameters as shown in the figure 5. All the basic layout parametersconfigurationareshowninfigure6

Figur.2bandgaprepresentationofstokesand anti-stokesprocess

2. METHODOLOGY

OptiSystemisanopticalcommunicationsystemsimulation softwarewhichcanbeusedtodesignopticalcommunication systemandsimulatethemtodeterminetheirperformance, given various component parameters. The range we are usingis1609nmandthedifferencebetweeneachchannel will be 10Mhz. For the simulation of SRS effect in WDM system, we required a Continuous wave laser (CW) array. andwehavetaken40ports asoutputsfromtheCWlaser array.Theotherparametersareconfiguredasshownin(fig. 7).AlltheoutputsfromtheCWlaseraregiventotheWDM Multiplexer(MUX).ThentheMultiplexeroutputwhichhave

Figure.4clearviewexperimentsetupforSRS

ToobservetheeffectofSRSonWDMsystemweare goingtokeepthepowerparameterat2mW.Andobservethe result.

WearegoingtoanalyzehowtheSRSeffecttheWDM systemwhenwegraduallyvarytheinputpowerintheWDM system. As we know that in multichannel when SRS is present the energy is transfer from one channel to neighboringchannelandatiltisformedattheoutput.

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056

Volume: 09 Issue: 12 | Dec 2022 www.irjet.net p-ISSN: 2395-0072

Figure.5layoutparametersofnon-linearopticalfiber

Toobservethe result, wehaveusedthe Optical Spectrum analyzer (OSA) which helps user to calculate and display optical signals in the frequency domain. OSA has been connected on both input and the output side as shown in fig.9,fig.11,fig.13.fig15.Clearviewoftheoutputimagesis showninfig.10,fig.12,fig.14,fig16.

Figure8OSAinputfor2mW

Figure6layoutparameterofSRSlayout

Figure7layoutparametersforCWlaser

3. RESULTS AND DISCUSSION

Nowwewillanalyzehowthepowerparametereffectsthe Ramantilt.Forwhichwewillvarythepowerparameterat the input as 2mw,10mw,25mw,50mw and observe the results.

Figure9OSAoutputfor2mW

Figure.10clearviewofOSAoutputfor2mw

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International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056

Volume: 09 Issue: 12 | Dec 2022 www.irjet.net p-ISSN: 2395-0072

Figure.11OSAoutputfor10mW

Figure14clearviewofOSAoutputfor25mW

Figure.12clearviewofOSAoutputfor10mW

Figure.15OSAoutputfor50mW

Figure.13OSAoutputfor25m

Figure.16clearviewofOSAoutputfor50mW

Wecanobservethatasweincreasetheinputpower the Raman tilt occurred due to the SRS effects gets steepening. And with help of WDM analyzer we see that Optical Signal to Noise Ratio (OSNR) goes on decreasing causingincreaseinBitErrorRate(BER).

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056

Volume: 09 Issue: 12 | Dec 2022 www.irjet.net p-ISSN: 2395-0072

4. CONCLUSION

This paper focusses on the effects of SRS along with the factors effecting SRS. SRS which power to be transferred from lower wavelength channels to higher wavelength channelswasinvestigated.Wefoundthatthisopticalpower tiltorthechannelsteepeningincreasewithincreaseininput power, due to which the Bit Error Rate (BER) increase causingdistortioninthereceivingsignal.ThiseffectinWDM systemcanbeminimizedbyusingunequalchannelspacing techniqueandcanreducetheunwantedpowertilt.So,the inputopticalpowershouldnotbetoolowortoohigh.Foran idealsystem,Powertiltshouldbezero.Therefore,inorder toreducethePowertiltvalue,minimumInputpowerand unequal channel spacing is to be given for the individual channels.

REFERENCES

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[2] A.Siddiqua,A.Ansari,A.M.FundóleandR.Jamadar,"8Channelwavelengthdivisionmultiplexing(WDM)with zero BER," 2016 IEEE International Conference on Recent Trends in Electronics, Information & CommunicationTechnology(RTEICT),2016,pp.21172120,doi:10.1109/RTEICT.2016.7808213

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[4] PoonamKumari,AbhishekTiwari,"StimulatedRaman ScatteringAnalysisofWavelengthDivisionMultiplexing (WDM) Channels in Optical Fiber" 2015 International Journal of Advanced Research in Computer and Communication Engineering (IJARCCE), 2015, Vol. 4, Issue4,doi:10.17148/IJARCCE.2015.4445

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