Muhammad Uzair Rasheed2009-CPE-03

UCE&T BZU MULTAN

WAVELENGTH DIVISION MULTIPLEXING

MultiplexingIs the set of technique that allow the

simultaneous transmission of multiple signals across a single data link.

Types of multiplexing

diagram

Multiplexing

Analog Digital

FDM WDMTDM

a multiplexing technique working in the wavelength domain

An analog multiplexing technique to combine optical signal.

Wavelength division mutliplexing

The concept was first published in 1970, and by 1978 WDM systems were being realized in the laboratory. The first WDM systems only combined two signals. Modern systems can handle up to 160 signals and can thus expand a basic 10 Gbit/s fiber system to a theoretical total capacity of over 1.6 Tbit/s over a single fiber pair.

History

In fiber-optic communications Wavelength –division multiplexing (WDM) is a technology which multiplexes multiple optical carrier signals on a single optical fiber by using different (colours) of laser light to carry different signals.

WDM

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.

Why Is WDM Used?

With the exponential growth in communications, caused mainly by the wide acceptance of the Internet, many carriers are finding that their

estimates of fiber needs have been highly underestimated. Although most cables included

many spare fibers when installed, this growth has used many of them and new capacity is

needed.

Three methods exist for expanding capacity

1)installing more cables,

2) increasing system bit rate to multiplex more signals

3) wavelength division multiplexing.

Type of WDM

1)CWDM2)DWDM

DWDM No official or standard definition Implies more channels more closely spaced

that WDM DWDM-based networks create a lower cost

way to quickly respond to customers' bandwidth demands and protocol changes.

A key advantage to DWDM is that it's protocol- and bit-rate independent.

Dense Wavelength Division Multiplexing

CWDM No official or standard definition number of channals is fewer than in dense

wavelength division multiplexing (DWDM) but more than in standard wavelength division multiplexing (WDM).

Laser emmission

Coarse wavelength division multiplexing

CWDM system have channel at wavelengths spaced 20 nanometers (nm).

DWDM 0.4 nm spacing Energy tolerance

CWDM&DWDM

• WDM technology allows multiple connections over one fiber thus reducing fiber plant requirement. – This is mainly beneficial for long-haul

applications.– Campus applications require a cost benefit

analysis.• WDM technology can also provide fiber

redundancy.• WDM provides a managed fiber service.

Benefits of WDM