Wavelength-division multiplexing (WDM) is a technology that multiplexes multiple optical carrier signals onto a single optical fiber by using different wavelengths of laser light. Modern WDM systems can handle up to 160 signals and expand a basic 10 Gbit/s fiber system to a theoretical total capacity of over 1.6 Tbit/s. There are two main types: coarse WDM (CWDM) uses channel spacings of 20 nm while dense WDM (DWDM) uses narrower spacings of 0.4 nm, allowing DWDM to carry more channels. WDM reduces fiber plant requirements by allowing multiple connections over one fiber.

4. Is the set of technique that allow the
simultaneous transmission of multiple
signals across a single data link.

5. Multiplexing
Analog Digital
TDM
FDM WDM
diagram

6.  a multiplexing technique working in the
wavelength domain
 An analog multiplexing technique to
combine optical signal.

7.  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.

8.  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.

10. 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.

11. 1)installing more cables,
2) increasing system bit rate to multiplex
more signals
3) wavelength division multiplexing.

12. 1)CWDM
2)DWDM

13.  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.

14.  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

15.  CWDM system have channel at wavelengths
spaced 20 nanometers (nm).
 DWDM 0.4 nm spacing
 Energy
 tolerance

16. • 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.