OPTICAL TECHNOLOGIES- WDM

Jun 16 • Notes • 1753 Views • 4 Comments on OPTICAL TECHNOLOGIES- WDM

OPTICAL TECHNOLOGIES-WDM

Wavelength division multiplexing:-

–The technology of combining a number of wavelengths onto the same fiber is known as wavelength division multiplexing or WDM.

– Wavelength division multiplexing is similar to frequency division multiplexing.Here the wavelength is properly divided in space to avoid interference of signals

Operational Principles of WDM:-

-The capacity of carrying the traffic signals along a channel is increased dramatically by using the wavelength division multiplexing.Now more data can be transmitted along the same line.

-An important feature of WDM is that it supports transparency.Thus  both digital as well as analog data can be sent over the same transmission channel or fibre

. -WDM provides end to end connection to its users.Thus the need of switching technology to switch the signal is avoided and thus it is more economical and congestion free.

Passive Optical Star Coupler:-

Star Coupler:-

– A NXN star coupler is a more general form of the 2 X 2 coupler.

– It combine the light streams from two or more input fibers and divide them among several output fibers.

– In the general case the splitting is performed in a uniform manner for all wavelengths so that  while entering the devics ,each of the N outputs receives 1/N of the power.

– The optical power from any input is evenly divided among the output ports.

– The total loss of the device contains splitting loss in addition to that the excess loss in every path through the star.

Isolators:-

– These are the devices which allow light to pass in one direction.Thus they prevent the loss due to scattering at the output.

-While designing the optical isolater,of the isolater should be independent  the state of polarisation.

Circulators:-

-the circulators are devices which sequentially pass light from one side to another.

-The circulators may be 2-port or 3-port or4-port.All have equal no of input and output ports.

-The function of a circulator is same as that of an isolator.

Active Components:- These are devices which require electical power for operation. EXAMPLE:-laser diodes and amplifiers.

MEMS Technology :-

– MEMS is also called microelectromechanical system.

– These are devices which combine mechanical, electrical, and optical components to provide sensing and actuation functions.

Variable Optical Attenuators:-

-These are used to control the optical power in an optical fibre.They are often used with an active component to maintain optical power even if the power at the input end changes.

– The cost and performance of these attenuators is the main concernfor its use.

–To control these attenuators mechanical and MEMS or electrooptic techniques are employed.

Tunable Optical Filters:–

– They are also known as tunable band pass filter because when they receive optical signal from one port they can direct a selected channel to the output port.

-.The selected channel can be chosen with the help of a remote control.

-They are mostly applicable for dense WDM  networks. .

Dynamic Gain Equalizers:-

– It is used for controlling the power levels indifferent channels.

-It  filters out individual wavelength by adding or dropping selective wavelengths

Polarization Controllers:-

– These are the devices which are used for the propagation of light rays.

-They contain a  polarization sensor and control logic which is used to control the polarisation of light.

– They  adjust any incoming state of polarization to an a output state of polarization through electronic control voltages.

Chromatic Dispersion Compensators:-

– The chromatic dispersion effects causes pulse broadening leading to increased bit error rate.Here the total dispersion of a travelling pulse is more and the system cannot function.That is when dispersion compensators are needed to remove the intersymbol interference in the network.

FREQUENTLY ASKED QUESTIONS WITH ANSWERS

1)WHAT ARE WDM AND WHAT ARE ITS OPERATIONAL PRINCIPLE?

Ans:-The technology of combining a number of wavelengths onto the same fiber is known as wavelength division multiplexing or WDM.

– Wavelength division multiplexing is similar to frequency division multiplexing.Here the wavelength is properly divided in space so as to avoid interference of signals

-The capacity of carrying the traffic signals along a channel is increased dramatically by using the wavelength division multiplexing.Now more data can be transmitted along the same line.

-An important feature of WDM is that it supports transparency.Thus  both digital as well as analog data can be sent over the same transmission channel or fibre

. -WDM provides end to end connection to its users.Thus the need of switching technology to switch the signal is avoided and thus it is more economical and congestion free.

2) WHAT IS A PASSIVE OPTICAL STAR COUPLER?

Ans:- Star Coupler:-

– A NXN star coupler is a more general form of the 2 X 2 coupler.

– It combine the light streams from two or more input fibers and divide them among several output fibers.

– In the general case the splitting is done uniformly for all wavelengths so that each of the N outputs receives 1/N of the power entering the device.

– The optical power from any input is evenly divided among the output ports.

– The total loss of the device consists of its splitting loss plus the excess loss in each path through the star.

3) WHAT ARE ISOLATORS AND CIRCULATORS?

Ans: Isolators:-

– These are the devices which allow light to pass in one direction.Thus they prevent the loss due to scattering at the output.

-While designing the optical isolater,of the isolater should be independent  the state of polarisation.

Circulators:-

-the circulators are devices which sequentially pass light from one side to another.

-The circulators may be 2-port or 3-port or4-port.All have equal no of input and output ports.

-The function of a circulator is same as that of an isolator.

4) WHAT IS MEMS TECHNOLOGY?

Ans:-

– MEMS is also called microelectromechanical system.

– These are devices which combine mechanical, electrical, and optical components to provide sensing and actuation functions.

5) WHAT ARE CHROMATIC DISPERSION COMPENSATORS?

Ans:- -The chromatic dispersion effects causes pulse broadening leading to increased bit error rate.Here the total dispersion of a travelling pulse is more and the system cannot function.That is when dispersion compensators are needed to remove the intersymbol interference in the network. 

GATE Syllabus-

1. Gate syllabus for Electronics and Communication Engg

IES Syllabus-

1. IES Syllabus for Electronics and Telecomm

2. IES Syllabus for General Ability

 

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4 Responses to OPTICAL TECHNOLOGIES- WDM

  1. Dinesh says:
    at

    WDM – Wireless Division Multiplexing is a most recently arrived and useful technology for the network communication. this article gives the information and advantage to know the importance of WDM.

    this article surely useful for everyone to know and inform the optical technology

    Reply
  2. Madhan says:
    at

    Optical technology is the recent technical fields and the questions which are here helps the students to know more about that technology.

    Reply
  3. priyanka nayak says:
    at

    wireless division multiplexing has acquired popularity in recent years because of many of its advantages.

    Reply
  4. Seetha Manoharan says:
    at

    WDM is the latest technology. most of the people doesn’t know about the applications of it.

    Reply

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