Wdm System Performance With Edfa Configuration Biology Essay

Published:

This essay has been submitted by a student. This is not an example of the work written by our professional essay writers.

Abstract - Today, Wavelength-division multiplexing (WDM) is deployed by many network providers for point-to-point transmission-but there is strong momentum to develop it as a full-fledged networking technology in its own right. In this paper characteristic and advantages of WDM network across C band were discussed with proven results from network performance analysis. EDFAs are widely used in fiber optic communication, which could provide minimum loss for telecom fibers application, have low noise and low polarization sensitivity. Suggestion on performance of EDFA in WDM also discussed in later of this paper.

Keywords- WDM, EDFA, C - band

Introduction

The advent of telecommunication in 1870s completely revolutionized the world of communications. Metallic cables consisting of twisted wire cables, co-axial cables were the media of choices for many years. These could be used efficiently up to frequencies of 10MHz but the system performance degraded beyond this range [1].

Wavelength Division Multiplexing (WDM) is a technique that multiple signals are carried together as separate wavelengths (colour) of light in a multiplexed signal [2]. WDM is used in optical fiber networks. The principle is identical to that used when we tune our television receiver to one of many TV channels. Each channel is transmitted at a different radio frequency and we select between them using a "tuner" which is just a resonant circuit with the TV set. The wavelength in the optical world is just the way we choose to refer to frequency and optical WDM is quite identical to radio FDM [3].

WDM and FDM (Frequency Division Multiplex) are both based on the same principles but WDM applies to wavelengths of light in optical fiber while FDM is used in electrical analog transmission. A WDM optical system using a diffraction grating is completely passive, unlike electrical FDM, and thus is highly reliable. Further, a carrier wave of each WDM optical channel is higher than that of an FDM channel by a million times in frequency (THz versus MHz) [4].

Wavelength Division Multiplexer is a device that combines optical signals from multiple different single-wavelength end devices onto a single fiber. Wavelength Division Multiplexer carries two to four wavelengths per fiber. The original WDM systems were dual-channel 1310/1550 nm systems. Typically, the same device can also perform the reverse process with the same WDM techniques: de-compose the data stream with multiple wavelengths into multiple single wavelength data streams, a process call de-multiplexing. Therefore, it is very often a Wavelength Division Multiplexer and Demultiplexer is in the same box [5].

Principles operation of wdm system

Figure 1: WDM long distance fiber transmission system [6]

The optical signals with several different signal of wavelengths and will combined it all together in a optical multiplexer as a input source. The signals from the multiplexer are travel along the same fiber link from the multiplexer through other device called as add-drop multiplexer in the middle and routes the signal in a single optical cable. An add-drop used to connect the signal to the multiplexer at the middle of the optical link.

For the output, the several wavelengths of the signals are split out from the demultiplexer. It is routed to separate the receivers into one for each wavelength at the output. The signals must be totally completely separated it out because any different signal with different wavelength will consider as noise at the receiver output.

Figure 1 can be illustrated where multiplexer and demultiplexer work a duplicate system where both of it is connect each other in the opposite direction on the same device. The multiplexer uses to combine the signal and the demultiplexer use to separates them. The major key of the operating considerations is quite difference between two of them. The multiplexers normally have a very low insertion loss to avoid scattering on the signal occur at any of the transmitters. The demultiplexer must be the most reliably on the separate signal on optical channels with minimum leakage of source light from the optical channel into an adjacent channel.

Optical aMPLIFIER

An optical amplifier is a device which amplifies an optical input signal directly, without the need to first convert it to an electrical signal and generates an output signal with higher optical power [7]. Amplifier characteristics such as operating wavelength and the gain bandwidth are determined by dopants rather than by fiber, which plays the role of host medium. The main types of optical amplifiers are Semiconductor Optical (SOA), Raman (RA), and Erbium Doped Fiber Amplifier (EDFA).

Figure 2: Basic Structure of Optical Amplifier [8]

EDFA

Erbium Doped Fibre Amplifier is the most attractive for use in fibre-optic communication networks as they operate near 1.55 µm where telecom fibres have minimum loss, noise and polarization sensitivity. This amplifier use trivalent erbium ions (Er3+) as a gain medium by doping the fibre core during the process. The Er3+ doped fibre is pumped with light from two laser diodes [9]. The pump laser excites ions into a higher energy from where they can decay via stimulated emission of a photon at the signal wavelength back to a lower energy level. Amplification is achieved by stimulated emission of photons from dopant ions in the doped fibre. EDFA can be used as power amplifier, in line amplifiers, as well as pre - amplifiers.

It is clear that EDFA are the best choice for optical amplification in present light wave systems. Erbium is used as dopant into glass host (fiber) and the doped fibre is used as an amplifying medium. Er doped fibres give an amplified output around 1550nm [10]. The EDFA is one is the key devices used for wavelength division multiplex (WDM) transmission systems. EDFAs are revolutionizing light wave system by reducing costs and enhancing network performance. Some of the advantages offered by EDFAs are:

High gain (-50dB)

High output power (>100mW)

Low noise figure (-4dB)

Less gain variation

Wide bandwidth of operating suiting WDM

Inherent compatibility to transmission fibre with low insertion loss

Cross talk immunity in multichannel systems

Some of limitations in EDFA amplifier are large size and high power consumption (efficiency -10dB/1mW) [11]

Figure 3: Schematic setup of simple EDFA [12]

SIMULATION MODEL AND RESULT

Optisys is a stand alone product that neither does nor relies on other simulation. It is a system level simulator based on the realistic modelling of optical fiber communication system.

Simulation Layout

The simulation setup is shown as in Figure 4. Four different wavelengths, 1550.61 nm, 1550.12 nm, 1541.35 nm and 1532.68 nm are combined by using WDM Multiplexer. Optical Spectrum Analyzer is used to illustrate and view the simulation result of the signal power and noise which are represent the OSNR parameter. EDFA amplifier and WDM Demuxltiplexer are used to complete the system performance that represented by BER Analyzer.

Figure 4: Simulation Layout WDM Network Performance

Eye Diagram Analysis

Wavelength

Noise (dBm)

OSNR (dB)

Power (dBm)

1560.61 nm

-9.102

4.844

-1.566 е 1

1550.12 nm

-7.389

0

-7.389

1541.35 nm

-7.389

0

-7.389

1532.68 nm

-7.389

0

-7.389

Although the signals are send/transmit in different wavelength, the results represented by BER Analyzer proved that, WDM is a specialized coupler [13]. Based on the eye diagram or eye pattern shows in figure 5, the results are similar for each wavelength. The more opening of the eye, the better signal quality represents. The eye diagram is use as oscilloscope that display of a digital signal repetitively sampled to get a good representation of its behaviour.

The result of this simulation proved that WDM is a very good multiplexer. WDM combines or expands signals of specific wavelengths to allow transmitting multiple signal of different wavelength on the same fiber. In the other word, user can increase the number of wavelength in the same fiber.

Figure 5: Eye diagram of four wavelengths

Parameters Analysis Using Optical Spectrum AnalyzerOSA I and OSA II

READING TAKEN AFTER MULTIPLEXER

READING OF OSA I (FOC I) AND OSA II (FOC II)

Wavelength

Noise (dBm)

OSNR (dB)

OSA I

OSA II

OSA I

1560.61 nm

-7.389

-8.629

16.932

1550.12 nm

-7.389

-7.744

16.947

1541.35 nm

-7.389

-7.661

16.932

1532.68 nm

-7.389

-4.754

16.947

READING OF POWER OSA I AND OSA II

Wavelength

Power (dBm)

OSA I

1560.61 nm

- 3.770 е 1

1550.12 nm

- 3.765 е 1

1541.35 nm

- 3.770 е 1

1532.68 nm

- 3.765 е 1

OUTPUT OF RECEIVER I

OUTPUT RECEIVER 14

Wavelength

Noise (dBm)

OSNR (dB)

Power (dBm)

1560.61 nm

-7.389

0

-7.389

1550.12 nm

-7.928

4.502

-3.427

1541.35 nm

-7.389

1.799

-26.69

OUTPUT RECEIVER 26

Wavelength

Noise (dBm)

OSNR (dB)

Power (dBm)

1560.61 nm

-7.389

19.650

-7.532

1550.12 nm

-7.389

19.665

-7.517

1541.35 nm

-7.389

19.650

-7.532

1532.68 nm

-7.389

19.665

-7.516

Wavelength

Noise (dBm)

OSNR (dB)

Power (dBm)

1560.61 nm

-7.389

0

-7.389

1550.12 nm

-7.389

3.433

-26.249

1541.35 nm

-25.693

5.134

-20.558

1532.68 nm

-7.389

3.267

-26.294

OUTPUT RECEIVER 34

Wavelength

Noise (dBm)

OSNR (dB)

Power (dBm)

1560.61 nm

-7.389

0

-7.389

1550.12 nm

-7.389

0

-7.389

1541.35 nm

-7.389

1.799

-26.693

1532.68 nm

-5.271

4.442

-3.052

DISCUSSION

Based on the simulation result, after the entire signal went from the multiplexer OSNR are 19.65 dB and the power signal became flatness -7.5 dBm from -25dBm for each incoming signal. OSA I used to visualize the output after the first fiber optic and OSA II used to visualize the output after the EDFA amplifier. For the OSA I output in terms of noise, the noise signal increased and the OSNR decreased. The situation might occur from some distortions or attenuation inside fiber cable and the OSNR decreased because the noise signals are higher than signal transmit. This may affect the power that used to transmit the desired signal. Eye patterns opening for all receivers are displayed in very smooth patterns. There was no signal overlap in the transmission signal.

Each WDM fiber has a certain bandwidth the range of frequencies it can carry. One advantage to WDM is that every user can transmit information at the highest rate possible all the time; WDM does not change transfer rates in proportion to the number of users on the line. Another large benefit to WDM is that it increases the amount of information that can be transferred without significant loss of signal integrity. In this simulation, any four fibers of the same quality, one signal will be lost just as fast as ten or more, so there is nothing to be lost and much to be gained from WDM.

EDFA is an effective optical amplifier because high gain, wavelength of amplification, large bandwidth, and low noise. When both OSAs are compared, this system provided low noise and better OSNR.

Writing Services

Essay Writing
Service

Find out how the very best essay writing service can help you accomplish more and achieve higher marks today.

Assignment Writing Service

From complicated assignments to tricky tasks, our experts can tackle virtually any question thrown at them.

Dissertation Writing Service

A dissertation (also known as a thesis or research project) is probably the most important piece of work for any student! From full dissertations to individual chapters, we’re on hand to support you.

Coursework Writing Service

Our expert qualified writers can help you get your coursework right first time, every time.

Dissertation Proposal Service

The first step to completing a dissertation is to create a proposal that talks about what you wish to do. Our experts can design suitable methodologies - perfect to help you get started with a dissertation.

Report Writing
Service

Reports for any audience. Perfectly structured, professionally written, and tailored to suit your exact requirements.

Essay Skeleton Answer Service

If you’re just looking for some help to get started on an essay, our outline service provides you with a perfect essay plan.

Marking & Proofreading Service

Not sure if your work is hitting the mark? Struggling to get feedback from your lecturer? Our premium marking service was created just for you - get the feedback you deserve now.

Exam Revision
Service

Exams can be one of the most stressful experiences you’ll ever have! Revision is key, and we’re here to help. With custom created revision notes and exam answers, you’ll never feel underprepared again.