Search Results for 'wdm'

[Ranjeet KumarParticipant]

Hi Atul,
Do you refer WDM add component as ADD component. AS WDM add Adds a WDM channel and a WDM signal.
Where as power Combiner combines evenly numberof inputs signals into a single output port.

[Ranjeet KumarParticipant]

Hi Hermawan Widiyanto,
Fist i suggest you to always use the symmetrical number of channels more precisely ..2, 4, 8, 16, 32, 64…. 2^n where n is positive integers.
Because in almost all the research work you would find these types of number of channels, i am quite sure why we should use such type.
I will try to find out and will share.
I suggest you to read some basic research works of DWDM system.
Please read the article :
http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=5549128
http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=1216189

[Dr. Dhiman KakatiParticipant]

Hi Ranjeet Kumar, Thank you so much for providing with some more valuable information, you are suggesting me to increase the bit rate to 40 Gbps, nut want to add that i did simulation with DQPSK modulation format that to with only 10 Gbps for single polarization with direct detection because upto 10 Gbps the system was running properly but when I increase it to some 11 or 12 Gbps the performance degrades drastically and very much inclined to error. so I think there are some limitation for each modulation scheme. Moreover you have mentioned that the DWDM system to set a bit rate of 40 Gbps to have better output, if a system is not giving better how it can give better result at much higher rate such as 40 Gbps, I need some more explanation regarding this.

Thanking you,
regards,
Dhiman

[Ranjeet KumarParticipant]

Hi Dhiman,
Here i am uploading 8 channel DWDM system using symmetrical compensation technique at data rate of 10 gbps.
In this design we have channel spacing of 100 ghz.
I use MDRZ modulation format.
you may change the data rate e.g. 20 gbps, 40 gbps and minimize channel spacing to 50ghz and 25 ghz .
And you will find the difference in results.
As we will decrease the channel spacing, results will degrade.

Seeking your response.

[Ranjeet KumarParticipant]

Hi Dhiman,
To achieve dense wavelength division multiplexing (DWDM) systems with high spectral efficiency, it should operate at bit rates of 40 Gb/s per channel. For DWDM systems in which the data rate is greater than 10 Gb/s/channel, the dnegative effects of dispersion and nonlinearities must be managed. Dispersion management, which utilize DCF fiber, is a key technique that keeps the total accumulated dispersion low while suppressing most nonlinear effects. In dispersion-managed systems utilizing single-mode fiber (SMF) and dispersion compensating fiber (DCF), the positive dispersion of SMF can be compensated by the large negative dispersion of DCF.
You should use :
1. Symmetrical dispersion compensation techniques instsead of pre or post dispersion compensation techniques to reduce the effect of dispersion
2. You should use advanced modulation formats like.. CSRZ, DRZ, MDRZ.

I also have faced problem in designing 25ghz channel spacing DWDM system.

i would like to share the link :
http://www.sciencedirect.com/science/article/pii/S0030402608003276

Hope this may help you.

[Ranjeet KumarParticipant]

Hi Dhiman,
The latest research in the fields of WDM/DWDM system includes:
1.Effective way to reduce the nonlinearities like Four Wave Mixing and Cross Phase Modulation so that we could achieve the spectral efficiency of 1 b/s/Hz or less, using various modulation formats.
2. We should use the concept of nonuniform channel spacing and nonuniform power assignment between adjacent channels of the DWDM system.
3. We should simulated increase the no. of channels beyond 128 channels.
4. We could reduce the channel spacing upto 25 ghz or smaller and increase the global data rate, to make more spectral efficient.
5. We could use some advanced modulation formats like CSRZ, MDRZ , OFDM.
Hope this will help you.

[Dr. Dhiman KakatiParticipant]

Hello Hermawan Widiyanto,
First of all put the CW laser array power in sweep mode and try to increase the power from around -7dBm to 4dBm in 7 iteration as I have seen in many examples of WDM systems, his is one way tou can modify and further keep the power along the fiber below a certain limit, because High intensity light waves causes nonlinear effects in the fiber and the system performance degrades. try using Optical amplifier wherever necessary and dispersion compensating fiber to increase the bit rate of the system. Thanking you.

please refer to the following link

Sweep power in WDM system

hope to get some more reply in that link.

Regards,
Dhiman

[Hermawan Widiyanto]

hello, i want to ask again. In my project, i made a DWDM-ROF (Radio Over Fiber) scheme with 20 channels with bitrate each channels it’s about 25Gbps and 65 km fiber length. The problems is still difficult for me to set or to define the best output power of CW laser with these spesification so i can reach the minimum value of Q factor. So, is there any formula or some technical spesification to calculate the appropriate output power for CW laser?

thanks and regards
hermawan.w

[Naazira BadarParticipant]

Well Jyoti Sharma..

Could be more clear with your query. what exacly is the issue with your system? Since WDM MUX/DEMUX have filters, the output channels are bound to have different power levels as long as some explicit power control circuitry is not used.
As going by the image shot you have attached, i think it is some design error. please post your osd or screenshot.

Regards
Naazira Badar.

[Duy Le NguyenParticipant]

Hi Gokul. Thanks for your reply.

I’m using 14 version, but i dont know about some parameters in new OFDM modul and demodulator.

And can i ask one more stupid question?

The system i attached below is WDM-RoF system, isn’t it?
Because i’m wondering the RoF system must have the radio modulator or not?
I’m making project follow OFDM for Optical Communications
of William Shieh and OFDM modulation sample file im sample folder.

Please reply me.
Regards.

[varinder singhParticipant]

hi dhimen,
so far i know about the future for the next genneration optical networks… these papers will help you …in wdm topics…..you can use these papers to get the idea about wdm and itz future in the comming days……
i hope you will be satisfied with my response thanks
with regards

[Dr. Dhiman Kakati]

Hello Everyone,
Presently I am working with WDM system samples that are available in the Optisystem 13 samples folder. Here I came across that there they have used power in sweep mode. why not in normal mode..? what are the advantages of using laser power in sweep mode. I am looking for how they are calculating inthose powers for each sweep…? one more noticeable is that all the power levels in the sweeps are in decimal, So there must be some technique or formula for calculating those powers.
I tried with my own set power at the sweeps still i am getting an expected output. So for optimum result there may be some formula.. looking for your reply. Thanking you in advance.

Regards,
Dhiman

[Dr. Dhiman KakatiParticipant]

Hello burhan num mina llah,
Hope you also get the same result as i have in the attached file, I just did very simple modification as in the previous reply of mine and you can also get further better result. I took the reference from “WDM Systems folder” available in the “OptiSystem 13 Samples” for making it dense wavelength division multiplexing you need to set wavelength separation lesser and look for better result and respective modification. In my attached file the frequency spacing is 200 GHz and got a better solution. You should try from your side and decreasing the spacing and look for results.

Regards,
Dhiman

[varinder singhParticipant]

Hi mohamed tosson,
i am uploading the osd file of OFDM qam design of different types.
One is 4 user unidirectional OFDM PON system.
Other is OFDM WDM bidirectional system.
https://dru5cjyjifvrg.cloudfront.net/wp-content/uploads/2016/04/DP-64QAM-transmissioin-w-matched-filter.osd
with regards

[varinder singhParticipant]

hi fady
In order to realize bidirectional ofdm system first you need to make a system using bidirectional fiber by placing ofdm transmitter and receiver on both sides .However working of bidirectional fiber in bidirectional system is little tricky ,you need to add null signals for upstream tx signals.Here are some examples of bidirectinal fiber and working

Lesson 5: Bidirectional Simulation — Working with Multiple Iterations

Use of BD in Bpon is given in this link

Broadband Optical System Based on a Passive Optical Network (BPON)

Try designing system by taking one Tx and Rx on both sides and if it works try to increase them.Let us know if our information helps and share your base paper or reference content you wish to reproduce for better information.

you query is related to issue, which has been already in discussion in past…

Bidirectional OFDM system

Bidirectional WDM OFDM PON

even ne was post by you also

i also appreciat fayi