**DWDM:

**

• DWDM stands for Dense Wavelength Division Multiplexing.
• It is a technology that allows multiple information streams to be transmitted simultaneously over a single fiber.
• Each signal is carried at the same time on its own separate light wavelength.
• Dense wavelength division multiplexing (DWDM) is a fiber-optic transmission technique that employs light wavelengths to transmit data parallel-by-bit or serial
  -by-character.
• It provides a cost effective method to increase the capacity of the existing networks without the need to add additional fiber.
• This application explains capabilities of the OptiSystem software to explore different design structures.

• to optimize the performance of these networks for access and long-haul application.

• Applications:

  • Long-haul optical networks either in point-to-point or ring topology.
  • Expanding the capacity of an existing optical network.
  • Capacity leasing for network wholesalers.
  • DWDM allows providers to offer services such as e-mail, video, and
    multimedia carried as Internet protocol (IP) data over asynchronous transfer mode (ATM) and voice carried over SONET/SDH.
• Benefits:
  • New Bit Error Rate Test set enables the simulation of millions of bits for direct error counting.
  • Multi-parameter scanning enables system designers to study trade-offs with respect to parameters of interest and to choose an optimal design for deployments.
  • Enables users to analyze different algorithms for the electronic equalization.
  • Interfaces with popular design tools.
  • Significantly reduces product development costs and boosts productivity through a comprehensive design environment to help plan, test, and simulate optical links in the transmission layer of modern optical networks.
  • DWDM also gives service providers the flexibility to expand capacity in any portion of their networks an advantage no other technology can offer.

Dense Wavelength Division Multiplexing (DWDM) components:

DWDM contains five main components:

DWDM Terminal Multiplexer

• DWDM Terminal Multiplexer device contains a one wavelength converting transponder for each wavelength carried.
• It receives an input optical signal, converts it to an electrical signal and then retransmits it as an optical signal, that is, a process abbreviated as O/E/O) using a 1550 nm laser beam.
• The MUX (multiplexer) takes a number of 1550 nm optical signals and places them on a single optical fiber. This terminal multiplexer may also contain an EDFA (Erbium Doped Fiber Amplifier) to amplify the optical signal.

Intermediate Line Repeater:

• These are amplifiers placed every 80 to 100 kilometers to compensate for loss of optical power; amplification is done by an EDFA, usually consisting of several amplifier stages.

Intermediate Optical Terminal:

• This is a remote site amplifier placed where the signal may have traveled up to 140 kilometers; diagnostics and telemetry signals are extracted or inserted.

DWDM Terminal Demultiplexer:

• This device breaks the multi-wave signal back into individual signals; these may be sent to O/E/O output transponders before being relayed to their intended destinations, i.e. client-layer systems.

Optical Supervisory Channel (OSC):

• This channel carries information about the multi-wave optical signal and may provide data about conditions at the site of the intermediate line repeater.
• DWDM is sometimes called wave division multiplexing (WDM) and WDM is growing denser as the technology evolves.