hybrid optical amplifier

[lavanya krishnan]

can anyone pls upload me some tutorial/simulation files on hybrid optical amplifier. i am new to optisystem

[alistu]

Hi lavanya and welcome to Optiwave forums. Here are some papers which might be useful on the subject:

http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=6459732&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D6459732
(The paper suggests how optical amlifiers could be combined for the benefit of long reach PONs)

http://web.stanford.edu/~shyin/Courses_files/Wideband%20Optical%20Amplifier%20Technology_Shuang%20Yin_EE247%20Term%20Paper.pdf
(The paper contains some hybrid optical amplifier simulations that have been done using Optisystem)

I suggest first taking a look at optical amplifier samples in Optisystem sample files. Let me know if these help.

Regards

[Dhananjay Patel]

Which amplifiers in hybrid optical amplifier are you exactly working and for what application? There is lot of work scope in hybrid optical amplifier.

[aasif bashir dar]

currently there is no tutorial in optisystem for hybrid optical amplifiers(HOAs).but u easily use raman and EDFA amplifiers for optisystem tool box to create desired HYbrid amplifiers.U can also reference books like keiser for it.

[Ashu verma]

Hello lvanya.Realization of HOA in optisystem is very simple.however you need to analyze flat gain curves for c band wavelengths nd l band.here i have attached some paper .check than and you will get to know how HOA can be made in optisystem.

Flat-Gain L-Band Raman-EDFA Hybrid Optical Amplifier for Dense… Have a look at it!
https://www.google.co.in/url?q=http://ieeexplore.ieee.org/iel5/68/6410445/06373695.pdf%3Farnumber%3D6373695&sa=U&ved=0CA4QFjADahUKEwjDlImZ9NTHAhVKoJQKHca0Cio&usg=AFQjCNF9JaIJd8knehGQUG0nz21xw04qiA

Performance Analysis of Hybrid Optical Amplifiers in 120 x 10 Gbps …. Have a look at it!
https://www.google.co.in/url?q=http://www.seekdl.org/nm.php%3Fid%3D4730&sa=U&ved=0CBAQFjAEahUKEwjDlImZ9NTHAhVKoJQKHca0Cio&usg=AFQjCNE1KtoHCt62d5SYfCPRBVczLW_pQQ

Novel Optical Flat-Gain Hybrid Amplifier for Dense … – IEEE Xplore. Have a look at it!
https://www.google.co.in/url?q=http://ieeexplore.ieee.org/iel7/68/6693740/06668882.pdf%3Farnumber%3D6668882&sa=U&ved=0CAgQFjAAahUKEwj84r7x9NTHAhUIupQKHdxwD3s&usg=AFQjCNFZqqt0jMBUyVMulWG0avoEu01gJA

In case you face any problem in implementation,share with us and we will try to corroct you

[lavanya krishnan]

thanks everyone for ur responses

[lavanya krishnan]

i would like to work on EDFA+raman amplifier.it would be very helpful for me if anyone can upload me any simulation file on HOA

[alistu]

You’re welcome. The implementation of HOA from papers seems to be as easy as using two optical amplifiers after each other. The important part is its design and effect on the system, and as long as you have a very basic understanding of the software and where to find the optical ampliifers, you can easily implement them. You may find Raman amplifiers harder to set, though. So have a look at optisystem samples regarding Raman amplifiers.

Below I am attaching one Optisystem sample for RA, to which I have added EDFA which increases power by 4 dB. This is NOT from any paper and just shows how the gains are added…just to directly address you question.

Regards

[Ashu verma]

Welcome lavayna,its great to help other members and share mutual knowledge.I would suggest you to go through paper i have attached in previous post.you will get to know basic idea and by reading system set part of these papers enable you to make HOA very easily in optisystem.All these paper implemented in optisystem and concentrate on Ranan and EDFa.Even then you will have any problem regarding these amplifier,we will help you for sure.
Cheers

[lavanya krishnan]

thahks brother alistu for ur upload

[alistu]

You’re welcome lavanya. I hope it has been helpful.

[Ashu verma]

Lvayna as alisthu said,file attached is to introduce how hybrid amplifier can be made.Now you need to read some paper and modify the parameters of these amplifiers.Gain and noise figure of these amolifiers very much depends upon pump power ,pump wavelength,core radius and length of these fibers in order to provide maximum gain and minimum nf with gain flattening over different wavelengths you need to work on these parameters.

[AJAYBEER KAUR]

hiii
I am working on hybrid optical amplifier. I was unable to open the model HOA.osd that alistu given. Could anybody help me how to open this? I have optisystem 7 version.

[lavanya krishnan]

you can open that file only if u use optisystem 9 or later versions u cant open it in optisystem 7 version

[alistu]

Hi Ajaybeer,

Actually, I have created it using OptiSystem version 13, and since the files created by OptiSystem newer versions are not being supported by OptiSystem older versions, you are going to have to open it using the same version, which is also the newest version (I think all the components I have used are available in OS 9, though).

Regards

[Swapandeep Kaur]

sir please could you attach the ieee papers as i dont have access to them

[Ravil]

Hi Swapandeep Kaur,

According to your question about attaching papers, – unfortunately any of us, as an Optiwave forum member, is not able to attached any materials that are not in a public access, i.e. any material that has author’s copyrights. These copyright rules and regulations are expanded to our forum and have been clearly declared by Optiwave Team (Damian if I am not mistaken) in one of the previous forums…

[Ravil]

Hi AJAYBEER,

I completely agree with Alistu about inability to open file created in a newer version that you might have at this moment. In a meanwhile, if I am not mistaken, I have a version of Optisystem 7 in one of my machines. Therefore, I can try to open the file that you need in a newer version. After that, I can insert the content in a version of Optisystem 7 and upload it for you to try open it…

[Ravil]

Dear AJAYBEER,

In what version of Optiwave your original file is written in? I should be able to help you with versions up to 14. That is the latest version that we have in our laboratory…

[alistu]

Hi Ravil,

If you are referring to the version of the file that I have attached in this forum page, I have used OptiSystem version 13.0.3 to create the file. If you did not have access to version 7 (as Ajaybeer has demanded), maybe you can kindly attach a screen shot of the design implementation. Unfortunately, I don’t have access to the software right now.

Regards

[AJAYBEER KAUR]

hello
I tried to open it in optisystem 11 version even I couldn’t open the HOA.osd model. Plz help me how this file will be opened.

[alistu]

Hi Ajaybeer,

HOA.osd that I have attached in this topic has been made with OptiSystem version 13, so you would not be able to open it using any older version. I suggest that you download the newest version of the software (which is version 14) from your profile to be able to open the aforementioned OptiSystem file then.

Regards

[alistu]

I have attached a screen shot of the implementation in my HOA.osd file since you may not be able to use the newer version (and if you use the 30-day evaluation, the files created by it cannot be opened by any other version after 30 days are over if you don’t have access to OptiSystem 14 anymore).

[gaganpreet Kaur]

Hi alistu i want to understand the difference between dynamic model and average model of Raman amplifier. which model should be used for WDM implementation.

[Alessandro Festa]

The average model uses a simplified version of Raman equations to simulate a Raman amplifier (see for example:
B. Min, W. J. Lee, N. Park, “Efficient Formulation of Raman Amplifier Propagation Equations
with Average Power Analysis”, IEEE Photonics Technology Letters, Vol. 12, No. 11, November
2000.).

The dynamic model uses a complete dynamic description of the equation, so it uses more time to compute. It depends on the level of accuracy that you need which model to use – please remember that you can also use the propagation fiber itself for Raman gain simulations!

[AJAYBEER KAUR]

Thanku very much Alistu.

[AJAYBEER KAUR]

Also thanku Ravil for helping me in this topic.

[gaganpreet Kaur]

Thank you so much alessandro for telling me difference between average model and dynamic model . i tried to simulate a simple 4 channel system but it showed no difference in the output. thank you so much again.

[Alessandro Festa]

You are very welcome gaganpreet! I think that for most of the applications the Average Model is ok…can you confirm that simulation time is quicker with it?

Regards,

Alessandro

[gaganpreet Kaur]

Hi Alessandro, system is so small that my system is so small that simulation time is just few seconds so there is no diffrence in simulation time. i have used a fiber span of 50 km .i just wanted to test it so jsut tried ….may be over longer distance i can get some difference.

[Alessandro Festa]

Ok I understand!

[Swapandeep Kaur]

we design wdm system using hybrid optical amplifiers. can we also design a tdm system using them>?

[Alessandro Festa]

Hi Swadapdeep,

of course hybrid amplification can also be applied to TDM systems…this type of amplification is suitable for any optical signal.
Do you have in mind any particular system?

Best Regards,

Alessandro

[alistu]

Hi Swapandeep,

As Alessandro mentioned, the hybrid optical amplifiers can be used for any system, since their influence is on the optical signal in the fiber, regardless of whatever modulation may have been used. However, I believe cost-efficiency is of importance, for example it may not be economical to use it in a short-distance access system in general.

Regards

[Swapandeep Kaur]

thank you sir. sir actually i want to design tdm system using raman-edfa ,soa-edfa,raman-soa and also the individual amplifiers for eg 16,32 bit tdm system and compare it with a wdm system.

[Alessandro Festa]

Hi, I am not an expert at all on SOA so my previous reply was actually about EDFA-RAMAN.

Do you have any particular design requirements?

[Swapandeep Kaur]

sir i am trying it for the first time but my aim is to find out which amplifier performs the best

[alistu]

For the comparison purposes, you can do the simulations using the amplifiers you want to compare to each other and then compare the results. This is more reliable but takes quite some time. However, you can take a look at the following page which simply introduces and explains about some of the amplifiers you have mentioned, just to have an overall understanding:

http://www.fiber-optic-tutorial.com/comparison-of-different-optical-amplifiers.html

Regards

[gaganpreet Kaur]

That was quite a consolidated information on optical amplifiers whcih is helpful to understand their differences at glance.But there is no mention of parametric amplifiers. from whatever knowledge i have gathered i understand parametric amplifiers to be wideband tunable amplifiers which are quite required by WDM systems snd with availbility of high power pump lasers their dependence on EDFA has led to their independent capabilities being exploited still normally parametric amplifiers rarely draw any interest in discussion of research… do i miss any of their disadvantages?

[alistu]

Hi Gaganpreet,

what you have mentioned is in a general sense about the parametric amplifiers. I believe Swapandeep’s question is more about the use of amplifiers she mentioned for a specific system (which uses TDM) than the general benefits of parametric amplifiers. Therefore, I believe some general ideas about amplifiers whose combinations she is using may be helpful in having a sense about the answer she is going to get doing the simulations.

Regards

[gaganpreet Kaur]

Hi alistu my question was in general sense only. actually my research is on parametric amplifiers but i did’nt find parametric amplifiers are much explored as widely used optical amplifiers for WDM systems . even today and from past many years optical amplifiers research is revolving around EDFAs. though my simulation results for parametric amplification outperform EDFA or its hybrids still a doubt remains on is their any practical limitation which leads to its low popularity and usage.

[alistu]

I believe the main reason for these amplifiers not being so popular nowadays is the fact that today, the focus is pretty much on other parts of the system rather than the channel to improve performance, so for example a simple EDFA along with complex DSP and coherent detection is preferred in many cases. That’s probably why these amplifiers are not developed that much for today’s systems.

Cheers!

[Swapandeep Kaur]

sir please could you provide the mathematics related to the different amplifiers like EDFA ,SOA…
Why raman-EDFa is the best hybrid amplifier?

[gaganpreet Kaur]

Thank you so much alsitu yes at high dat rates coherent detection is needed though these systems are hardware intensive.thanks again and Regards

[alistu]

You’re welcome Gaganpreet.

Regards

[gaganpreet Kaur]

Hi Swandeep i have some material which may give you where insight to why Raman-EDFA hybrid is preferred and over what bands . you may kindly go through them.

[Swapandeep Kaur]

What is the use of loop control that has been used in wdm examples of optisystem?? can we design the system without it?

[alistu]

Allow me to exemplify this: If you are using a 500 km fiber which needs optical amplifier every 100km, you can easily use a 100km fiber followed by an amplifier and put it in a loop using loop control, setting number of loops to 5. Otherwise, you would have to connect 5 pieces of fiber and 5 amplifiers. However, you can certainly simulate the system without using it.

[Swapandeep Kaur]

thank you so much sir. I only need to compare the performance of optical amplifiers individual and hybrid amplifiers in 16,32 and 64 wdm system.

[Swapandeep Kaur]

do i need to use a fiber before and after the optical amplifier or one fiber beforethe amplifier is sufficient?

[alistu]

You’re welcome. You do not need to use the amplifiers both before and after the fiber in case you are using loop control. Either you put it before or after the fiber, you can make the comparison. However, you should see why you are using the amplifiers in the system (as power booster, pre-amplifier, or in-line amplifier).

[Swapandeep Kaur]

from where do we get the component edfa ideal? how is it different from normal edfa?

[Swapandeep Kaur]

ok i got it,it is under edfa as ” optical amplfier”

[alistu]

I am sorry Swapandeep I could not find such a component in optiSystem libraries (even though I searched the component in all the libraries). Can you please determine the exact address of the component? Unless you are talking about the EDFA black box component which is available in the same folder.

[Swapandeep Kaur]

sir which amplifiers do we usually consider while comparing optical amplifiers? like for edfa normal edfa? for raman average power model and for SOA Travelling wave SOA??

[alistu]

Please clarify what I mentioned about EDFA in my comment #29619 so that I would be able to explain it. About Raman, I would like to refer you to the good explanation given by Alessandro in this topic in reply #29436 where he states the choice depends on the level of accuracy needed in simulation.

[Swapandeep Kaur]

sir it was the optical amplifier component in the edfa folder renamed as edfa ideal.

[alistu]

Then I guess we are using different OptiSystem versions! I have EDFA black box component in the OptiSystem library among amplifiers, which does not require detailed design of the amplifier in order to perform with the defined characteristics. Please seeif the ideal EDFA also has the same performance.

[Swapandeep Kaur]

thank you sir. please explain about choice of edfa and soa..

[alistu]

I believe you can proceed with comparison by using traveling wave SOA as in-line amplifier as you mentioned in your own comment. Since your work is comparison, you can use EDFA black box (or the EDFA ideal; if it has the same characteristics as those I mentioned for EDFA black box in my former comment).

Regards

[Swapandeep Kaur]

thank you sir.sir i am using optisystem 7 and under edfa , there is “optical amplifier” component that has beeen named in the sample file as edfa ideal.

[alistu]

You’re welcome Swapandeep. Here I have attached an image of EDFA black box in OptiSystem 13. You can see it and compare it to EDFA ideal in version 7 to see if they perform more or less in the same way if you think it may help you in any way. Maybe they are the same component with the name changed.

[Swapandeep Kaur]

sir i think they are two different components because edfa black box component is also present and also the ooptical amplifier.

[alistu]

Thank you for letting me know of this.

Regards

[Swapandeep Kaur]

sir we have to find output power vs length in absence and presence of non linearities .What will be the non linearities? polarisation?

[alistu]

Nonlinearity factors include self-phase modulation and some other factors that may cause problems for WDM systems. in order to eliminate the effect of this factor, you can click on “nonlinearity” tab in the optical fiber properties to see all the related settings there. Can you explain more about polarization?

[Swapandeep Kaur]

polarisation is due to ions present in edfa . Polarisation sensitivity is the difference in gain of an input signal in one polarisation to the gain in the orthogonal polarisation.
i wanted to ask whether it is a nonlinearity?

[alistu]

If you mean to ask whether polarization can be effected by nonlinear effects or not, it can. In other words, the polarization can depend nonlinearly on the power of the optical field as far as I am concerned, as it can affect the phase of the optical wave propagating through the optical medium in SPM.

[Swapandeep Kaur]

please check this simulation file. it is giving more quality factor in presence of self phase modulation and less in absence of self phase modulation.it is in optisystem 7

[alistu]

the negative effects of nonlinearity can be seen while injecting high amounts of power into the optical fiber. For example, if you do the simulation with and without self-phase modulation with the laser power being 25dB, the negative effects of the optical fiber nonlinearities will be quite obvious.

[Swapandeep Kaur]

wont the same simulation run by just changing the optical amplifiers like replacing edfa by raman? keeping rest of the circuit same?or are there changes to be made?

[alistu]

Provided that the settings for the pump frequency are set correctly, I don’t think any problems should occur using Raman instead of EDFA in your implementation. The pump parameter can be seen as “upper pump reference” parameter in both the dynamic model and the average power model available in library.

[Swapandeep Kaur]

thank you sir. Since i am implementing a wdm system, i have directly used a wdm transmitter( 16 channel) with 193.1 Thz frequency and 100 Ghz spacing.

[alistu]

You’re welcome Swapandeep. I know about the transmitter you have been using in the .osd file and when I asked you to increase the laser power in my former comments (in order to see the nonlinear effect of SPM), I meant increasing the integrated laser in transmitter. Sorry if it confused you.

[Swapandeep Kaur]

please dont be sorry sir. sir were you able to open the osd file? is it fine? i think there is some mistake somewhere because i am not getting proper results..

[alistu]

Yes, I managed to open your file and I made a comment on how to see the effect of self-phase modulation in your implementation as you had asked. I managed to get the Q-factor of about 4 (with the corresponding BER of about 1e-5). So I can say I don’t see any mistakes in implementing the system.

[Swapandeep Kaur]

and i do not get any result when i replace the edfa by raman amplifier though i increased the wdm transmitter power to 10dbm , more than that is taking too long to execute.

[alistu]

The reason for the calculations taking so long is the fact that by increasing the input power, the nonlinear effects have kicked in. I suggested increasing power just to see the SPM effect. Please see if you face any problems in getting results by using less input power in your simulations.

[Swapandeep Kaur]

yes sir, even i am getting these values but i am getting no result in case of raman amplifier.

[alistu]

Please consider my suggestion in reply #29650.

Regards

[Swapandeep Kaur]

sir sorry to bother you again but in case of raman amplfier the problem is not of time, but its not giving any eye diagram or result…i am not getting where the problem is, ihave set the pump frequency still not getting the output.

[alistu]

Please upload the file with Raman amplifier being used. I will try to help if possible.

[gaganpreet Kaur]

Sorry to interrupt but i suggest wdm power of 10 dBm is too high. major difference in edfa and Raman amplifier outputs stems from pump frequency . u may use power meter at output of amplifier both EDFA and Raman. difference in output will suggest you if it is matter of meeting minimum power requirements. next you use optical spectrum analyzer and WDM across amplifier again in both cases of EDFA and Raman. it will help you analyze problem area is it low signal availability in case of Raman or increased noise. accordingly you may vary it pump frequncy tuning.i hope it helps.

[Swapandeep Kaur]

sir please find the attached osd file
thank you ma’am. ill try whatever you suggested.

[alistu]

Hi Swapandeep,

You have forgotten to pump the Raman amplifier and that is why the problem has happened. In fact, without the pump, Raman amplifier is somehow not considered in the calculations and consequently there is no signal in the output as in your case. Please try this and see if the problem is hopefully over.

Regards

[Swapandeep Kaur]

sir but i am not getting how to set the pump? i am using it for the first time. the upper pump frequency has been set. What else has to be done?

[alistu]

The upper pump limit must be set according to the pump frequencies used. Please go to OptiSystem samples and find the samples in the folder “Raman”. There are two examples in that folder: One regarding average power model and one regarding dynamic model. The average power model will help you set up the amplifier.

[Swapandeep Kaur]

thank you sir. i went through the tutorials but its not explained how the upper pump frequency is set but the values are given directly. I think we are taking wdm transmitter frequencies as 1552 nm (193.1 Thz) and spacing (.8nm) 100 GHz, and channels are 16, then pump frequency should be 1540 nm . but still i am not getting any result. is it because the frequencies at the transmitter are in thz and in raman amplifier in nm? i am attaching the file.

[alistu]

Since you are using an older OptiSystem version, do you have access to OptiSystem sample files that I mentioned in my previous comment? If yes, you can see how the Raman amplifier is pumped for average model. The upper pump frequency can then be set according to the frequency chosen for the pump.

[Swapandeep Kaur]

sorry to bother you again sir, but i am not getting how the particular pump upper frequency is set. please help if possible, i have gone through the tutorials, it has not been explained how the particular value is obtained, only the value is given directly.
This line has been given in the tutorial “The upper pump reference is set to 1500nm, after the amplifier is pumped at 1450 nm and the signals start from 1546 nm.”

[alistu]

I don’t think it would be of any help if I upload a file showing how it can be done since you are using an older version of OptiSystem software and it is not possible for you to open it. So can you please consider my question in reply #29714 where I have asked about the OptiSystem sample .osd files?

[Swapandeep Kaur]

sir in this wdm edfa simulation which i am attaching , the q factor is increasing with distance in absence of self phase modulation, at distance of 50 km , its 3.94, and at distance of 100 km ,it is 4.84. please check…

[alistu]

Hi Swapandeep,

You are right. I checked the system and realized what you mentioned is happening. Even I increased sequence length and no difference was made. And this has nothing to do with the optical amplifier being used in the system, since the system had the same problem even by disabling the amplifier component.

Regards

[Swapandeep Kaur]

sir with soa , the q factor is decreasing with increase in distance… but the thesis which i read, in that , for edfa the q factor is decreasing with distance and for soa , the q factor isincreasing with distance, exactly opposite…

[Swapandeep Kaur]

sir please reply

[alistu]

My expectation is that the system performance should always deteriorate as the distance increases. And as I mentioned in my previous comment, I omitted the EDFA amplifier that you were using and still had the same results, with BER being better at longer distances. So this had to do with the fiber channel rather than amplifier.

[Swapandeep Kaur]

sir please suggest should i try out the simulation with the diagram shown in the paper that i am attaching with this comment. but will it work with soa, raman amplifier?

[alistu]

I cannot find any attached paper to your comment Swapandeep. Please also address the exact diagram after attaching it. I would also like to know about the work done in the thesis which suggests the system performance should become better as the distance increases when self-phase modulation is disabled.

[Swapandeep Kaur]

sir in the case of soa , it is shown that at a distance of 120 km , highest q factor is obtained. so q factor initially increases with length till 120 km and then it decreases. i am attaching the thesis as well as the paper i mentioned.the diagram is the one of optisystem
i wanted to thank you sir. i decreased the dispersion to 2 and i think i am now getting correct results. will update you soon.

[alistu]

Thank you for the attachments. Sure the diagram shown can be implemented using other amplifier types. However, in many applications the Raman amplifier is used as a preamplifier, meaning it is used before the receiver. But if you want to compare their performance in terms of power booster (which is used after the transmitter), it is O.K.

[Swapandeep Kaur]

sir i wanted to ask whether i should implement the diagram given in the paper or the one which i made earlier. the one which i made earlier is giving correct results( q factor is decreasing in case of edfa in absence of self phase modulation). However,in case of soa, it initially increases and then decreases and again increases,.

[alistu]

As I mentioned, it depends on whether you would like to implement power booster, in-line amplifier or preamplifier. I suggest you go with the one you uploaded earlier in case of in-line amplifier or preamplifier. It really depends on the application of the amplifier and you have to determine that first.

[Swapandeep Kaur]

sir also the difference in values in absence and presence of spm is very less like 4.98 in absence of spm and 4.95 in presence of spm

[alistu]

I pointed out in our previously discussed issues in the same topic that self-phase modulation and many other nonlinear effects influence the system only when the power of the signal entering optical fiber is too high. Otherwise, their effect can be negligible depending on the level of the optical power.

[Swapandeep Kaur]

ok sir. thank you so much sir.

[alistu]

You’re welcome Swapandeep.

Regards

[Swapandeep Kaur]

sir i am still not getting as to how to set the upper pump frequency of the raman amplifier though i have gone through the samples that you mentioned in your earlier comment. could you please explain in words as to how that particular value of freq is obtained or which formula is used?

[alistu]

What I suggested in my former comments was to use laser pump for Raman amplifier in your implementation. After that, you should set the upper pump frequency according to the frequencies you chose for the laser pump. Have you tried using laser pump as I suggested? If so, please upload the file.

[Swapandeep Kaur]

thank you sir. got it. this is how i used the laser pump.

[alistu]

I ran your simulation and managed to get results. To improve the performance of the amplifier, you may consider using array pump even though it increases the cost of amplifier. I have attached an example of laser array pump used in your system. You wouldn’t be able to open the .osd file so I have just attached a screen shot.

[gaganpreet Kaur]

of course number of pumps increased may give u better performance but i dnt think its need for system u are implementing. it will add to cost only. moreoevr number of pumps, their power and frequency need optimization. theoretically research says pumps more than 8 lead to increase noise due to pump-pump interactions

[alistu]

Definitely there should be a trade-off between the cost imposed by several pumps being used and the performance of the Raman amplifier in the implemented system, and I believe the array pump used in the OptiSystem average model sample merely seems to be showing how to use a pump array. Was it helpful Swapandeep?

[Swapandeep Kaur]

thank you gagan ma’am and alistu sir. but i didnt try out simulation using the array since i thought the results were fine with the single pump alone

[alistu]

You’re welcome, Swapandeep. From reply #29786 I thought there may be something wrong with it (for example Q-factor of about 3.5 is inadequate for your purpose), but then I believe comparison can be made with all qualities of signal, taking into consideration the fact that Raman can perform better being given more pumps.

Regards

[Swapandeep Kaur]

sir since edfa and soa are also giving q factors of about 4 and the comparison is to be made between the three, i thought a single pump would be sufficient since it is also giving a q factor of about 4. or should i try with an array?

[alistu]

If you are comparing Raman-SOA with Raman-EDFA, definitely not. Otherwise, if you are for example writing a paper or something, I believe the purpose of your work really matters. You can see first why multi-pumped Raman amplifier is used in the first place to see if it is necessary for your work.

[Swapandeep Kaur]

sir i am working on my thesis and my first objective is to compare the individual amplifiers , later i would take up hybrid amplifiers. sir as you say, i will simulate raman amplifier with multi pumps array …

[alistu]

Here is a link from Optiwave where the use of multi-pumped Raman for gain flattening is discussed. You can see a pump array with 12 lasers has been used for this purpose and the references are all mentioned at the buttom:

Flattening the gain of broadband Raman amplifier with multipump configuration

[Swapandeep Kaur]

thank you sir

[alistu]

You’re welcome, Swapandeep.

Regards

[Swapandeep Kaur]

SIR for getting the values like output power in the simulation i am carrying out, we would place the dual port analyser across the optical amplifier?

[alistu]

Since the dual port WDM analyzer calculates the gain and flatness of your optical amplifier, you should connect it across the optical amplifier as you have mentioned. In case you are making use of a hybrid optical amplifier, then this means connecting it across both amplifiers used in the design.

[Swapandeep Kaur]

sir please reply

[Swapandeep Kaur]

SIR the results obtained by me (which i am attaching ) are different from the one given in the thesis on pg no 50,please check.I have attached Q FACTOR vs length in absence of non linearity

[alistu]

Can you please also address the corresponding figure in the thesis? I could not find it with a look into it (if that is the thesis the graphs should be in). Also it would be helpful if you address the parts in the thesis where the systems settings are determined, the comparison between implementations can be made.

[Swapandeep Kaur]

sir the figure is 3.5 on page 50 and the parameters are on pg 47 but they are not the same as i have used. should i change them ?

[Swapandeep Kaur]

sir figure is 3.5 on pg 50 and parameters are on pg 47 but they are different from my parameteres , should i change them?

[alistu]

If you intend to get results more or less the same as the ones in the figures, then the system configuration should be more or less the same. Even though this should be done, I still believe that there should be some similarities between the results that are obtained by both system configurations.

[Swapandeep Kaur]

this means that the results that i am getting are incorrect?

[alistu]

Not really. I believe your system configuration is OK, but it is different from that of the systems implemented and examined in the aforementioned thesis. The most prominent difference between your results and those of the thesis is related to the results obtained for Raman amplifier in my opinion.

[Swapandeep Kaur]

sir is it only the raman amplifier or there is something wrong with all the three amplifiers. i am attaching the ber vs length in presence of non linearities as shown in fig 3.6 on pg 50 in the thesis. please check and comment.. thank you

[alistu]

The trend of changes in the figures you have obtained is very much similar to those in the thesis, so the implementation is OK. I think the differences in values is because of the differences in parameter settings. Unless you use the exact settings, it is hard produce the same results (with the same software). In the former figure, Raman was very different, but now EDFA is different.

[Swapandeep Kaur]

thank you so much sir. sir why does raman – edfa provides better performance than other hybrid amplifiers?

[alistu]

You’re welcome Swapandeep. They have proven more effective especially in long-haul systems in terms of gain flatness, gain value, bandwidth and all in all, they are more cost efficient to be used there. However, each type of optical amplifiers have their own advantages and disadvantages and for some other applications, use of other hybrids might be better.

[Swapandeep Kaur]

thank you sir. in the thesis, which i sent to you, its shown on pg 27, fig 1.12 that it is because of the gain spectra of the two amplifiers.and given on pg 28 that the gain spectra of the two have opposite slopes………is that the reason. then they must subtract

[alistu]

You’re welcome Swapandeep. What is mentioned is the reason behind the gain flatness that I mentioned in my previous comment, which I believe to be one of the most important features of hybrid Raman-EDFA (otherwise high gain can be achieved using other hybrid amplifiers or non-hybrid amplifiers).

[Swapandeep Kaur]

sir do you have mathematical analysis of BER and dispersion?

[alistu]

There are analytical calculations of BER which are presented in digital telecommunication courses and regard basic fundamental concepts. Are you seeking such explanations? As for the basic concepts of dispersion, i suggest you go through the book “optical fiber communications” by Agrawal, unless you would like specific information.

[Swapandeep Kaur]

sir please give some good mathematical analysis of optical amplifiers. is maths from “fiber optic communication by gp aggarwal” fine?
“

[alistu]

Indeed the information provided in Mr Agrawal’s book is quite helpful. However, it may take quite some time to study the material. I have gone through the explanations given in the book written by Mr keiser more concise and more suitable for study to achieve general information on different optical amplifiers.

[Swapandeep Kaur]

sir the graphs which i sent to you, my sir(guide) wants me to mathematically check them through ber and dispersion formulas. like i set dispersion to 2 ps/nm/km

[alistu]

For better understanding dispersion for your purpose, I believe the book written by Mr Agrawal (optical fiber communication systems, almost all of the editions) are suitable, as the book discusses the issue from a very basic point. reading this, the dispersion can be calculated in the optical fiber.

[Swapandeep Kaur]

sir i have to perform the mathematical analysis of the optical amplifiers and that involves gain and noise figure calculation but in our simulation ,we have already fixed the gain and noise figure. should i change it to the normal edfa component? also i read that gain of edfa becomes negligible with increase in input power and in our simulation , we have set it to 10 db (for noting non linearity effects). what should be done?

[alistu]

Unless the design of the optical amplifier itself is of importance, I believe black box EDFA component can be used. You only need the gain and noise figure to consider in your calculations as you have pointed out. You have disabled nonlinearities, so you should consider noise figure and dispersion in your calculations.

[Swapandeep Kaur]

sir meanwhile i am trying out with the normal edfa and hopefully, i am getting the results….

[Swapandeep Kaur]

no sir, i am getting negative gain

[alistu]

Could you please explain what you mean by “negative gain”? I have heard of the cases with the gain having values between zero and one in electrical components and therefore causing loss. However, if the amplification is not done in the desired way, appropriate setting of the EDFA amplifier component is required.

[Swapandeep Kaur]

sir for calculating gain, we will take input power obtained at the dual port analyser at the amplifier?

[alistu]

To calculate gain and noise figure, the information provided by dual port WDM analyzer can be used. However, in case you are using components acting as the black box (such as EDFA black box), there is the option of choosing the gain as the parameter you can set to be constant in the whole spectrum.

[Swapandeep Kaur]

sir i was getting output power lesser than input power , so when i substituted it in the formulae (pout-pin)/ppump=PCE=lambda,p/lambda,s and Gain=(lambda,p/lambda,s)*ppump/pin i got negative values because i took input power as power of wdm tramsmitter

[alistu]

Thank you for the explanation. Negative values in logarithmic scales are the same as the values between zero and one as I mentioned in my previous comment. If you are using the EDFA component (not the black box), you should change the parameters according to the work you are trying to reproduce.

[Swapandeep Kaur]

sir erbium ion density is given as e+025 . does it mean 10 to the power of 25?

[Swapandeep Kaur]

ok sir, got it, thank you

[Swapandeep Kaur]

sir how will we calculate e to the power (4*10 to the power 15)

[alistu]

I don’t exactly understand your question regarding how the calculation is done. Maybe it will be helpful if I mention the other notation used for this purpose: A number can be written either as 5e11 or 5*10^11. So 4*10^15 that you have mentioned can be written in the following form also: 4e15.

[alistu]

I believe this discussion is getting really lengthy and hard to follow and besides, some of the points discussed are somehow deviated from the main topic of this forum page (hybrid optical amplifier). So if you don’t mind, you can start a new topic with the proper title where we can continue this. Thank you.

[Swapandeep Kaur]

sir i want to ask how to solve e raised to the power of 4e15 meaning e^4*e15

[alistu]

This can easily be solved using Matlab software. neper number to a certain power can be expressed using exp() function in Matlab, where in the paranthesis the expression for the power should be written. In your case, you would have to write exp(4e15), which yields a very very large number (Inf).

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