WDM SYSTEMS

In fibre optic communications Wavelength Division Multiplexing or WDM is a technology which multiplexes a number of optical carrier signals onto a single optical fibre by using different wavelengths of laser light. This technique enables us to get high bit rate and efficient use of fibre bandwidth. WDM allows communication in both the directions in the fiber cable.
In WDM, the optical signals from different sources or (transponders) are combined by a multiplexer, which is essentially an optical combiner. They are combined so that their wavelengths are different. The combined signal is transmitted via a single optical fiber strand. At the receiving end, a demultiplexer splits the incoming beam into its components and each of the beams is send to the corresponding receivers.

1. DEPARTMENT OF ELECTRONICS ENGINEERING SCHOOL OF ENGINEERING AND TECHNOLOGY PONDICHERRY UNIVERSITY,KALAPET, PUDUCHERRY-605014   SIMULATION ON “WDM SYSTEMS” SUBMITTED BY FAIZAN SHAFI [21304012] ECENG-636 [FSON] M.Tech (ECE) – II year SUBMITTED TO Dr. R. Nakkeeran ASSOCIATE PROFESSOR Dept. Of Electronics Engineering

2. CONTENTS WAVELENGTH DIVISION MULTIPLEXING CATEGORIES OF WDM WORKING PRINCIPLE OF WDM ADVANTAGE & DISADVANTAGES OF WDM APPLICATIONS OF WDM SIMULATED DIAGRAM INPUT & OUTPUT FIBRE SIGNAL BER ANALYZER OUTPUTS SOFTWARE USED REFERENCES

3. WAVELENGTH DIVISION MULTIPLEXING In fibre optic communications Wavelength Division Multiplexing or WDM is a technology which multiplexes a number of optical carrier signals onto a single optical fibre by using different wavelengths of laser light. This technique enables us to get high bit rate and efficient use of fibre bandwidth . WDM allows communication in both the directions in the fiber cable. In WDM, the optical signals from different sources or (transponders) are combined by a multiplexer, which is essentially an optical combiner. They are combined so that their wavelengths are different. The combined signal is transmitted via a single optical fiber strand. At the receiving end, a demultiplexer splits the incoming beam into its components and each of the beams is send to the corresponding receivers. 3

4. EXAMPLE The following diagram conceptually represents multiplexing using WDM. It has 4 optical signals having 4 different wavelengths. Each of the four senders generates data streams of a particular wavelength. The optical combiner multiplexes the signals and transmits them over a single long-haul fiber channel. At the receiving end, the splitter demultiplexes the signal into the original 4 data streams. 4

5. CATEGORIES OF WDM Based upon the wavelength, WDM systems are divided into three categories:- Normal(WDM ) :-   Normal WDM (sometimes called BWDM) uses the two normal wavelengths 1310 and 1550 nm on one fiber. Coarse WDM (CWDM)  :- CWDM generally operates with 8 channels where the spacing between the channels is 20 nm (nanometers) apart. It consumes less energy than DWDM and is less expensive. However, the capacity of the links as well as the distance supported is lesser. Dense WDM (DWDM)  :- In DWDM, the number of multiplexed channels are much larger than CWDM. It is either 40 at 100GHz spacing or 80 with 50GHz spacing. Due to this, they can transmit the huge quantity of data through a single fiber link. DWDM is generally applied in core networks of telecommunications and cable networks. It is also used in cloud data centers for their IaaS services. 5

6. WORKING PRINCIPLE OF WDM WDM is a technology that enables various optical signals to be transmitted by a single fiber. Its principle is essentially the same as Frequency Division Multiplexing (FDM). That is,  several signals are transmitted using different carriers, occupying non-overlapping parts of a frequency spectrum. WDM technique enables  bidirectional communications over a single strand of fiber, also called  wavelength-division duplexing , as well as multiplication of capacity. Most WDM systems operate on  single-mode fiber optical cables  which have a core diameter of 9 µm. Certain forms of WDM can also be used in multi-mode fiber cables (also known as premises cables) which have core diameters of 50 or 62.5 µm. 6

7. ADVANTAGES OF WDM Advantages of WDM are :- Easier to reconfigure Full duplex transmission is possible It provides higher bandwidth Optical component are similar and more reliable High security This could be the best approach as it is simple to implement 7

8. DISADVANTAGES OF WDM Disadvantages of WDM are :- Signals cannot be very close i.e., signals are more crowded Cost of the system increases with the addition of optical components Difficulty in wavelength tuning Difficulty in a cascaded topology Costly 8

9. APPLICATIONS OF WDM Applications of WDM are :- The technology of WDM is widely used in  Optical Transport Networks . The rapid growth of data service demands a higher quality of the capacity of transmission equipments, network bandwidth and the ability of multi-service transmission. In SONET network. Dense WDM multiplexing allow to muxed and demuxed numbers of channel closer to one another to achieve greater efficiency. Optical transport network. Local exchange network. 9

10. SIMULATED DIAGRAM 10

11. INPUT FIBRE SIGNAL 11

12. OUTPUT FIBRE SIGNAL 12

13. BER ANALYZER OUTPUT 1 13

14. BER ANALYZER OUTPUT 2 14

15. BER ANALYZER OUTPUT 3 15

16. BER ANALYZER OUTPUT 4 16

17. SOFTWARE USED OPTISYSTEM 19 17

18. REFERENCES https://en.wikipedia.org/wiki/Wavelength-division_multiplexing https://www.tutorialspoint.com/wavelength-division-multiplexing https://www.ciena.com/insights/what-is/What-Is-WDM.html https://www.smartoptics.com/this-is-wdm/the-basics-of-wavelength-division-multiplexing-wdm/ 18

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