What is Dense wavelength division multiplexing ( DWDM )

[Super Gyandev]

Hi,

I want to know about what is dense wavelength division multiplexing ( DWDM ) ?? And what are the its advantages and disadvantages ???

[Tomaz]

DWDM (dense wavelength-division multiplexing) the WDM (Wavelength Division Multiplexing) is a single strand fiber for each channel of the multiple lambda (wavelength) is a technology transfer at the same time.

For example, the wavelength from 1550nm to 1300nm wavelength separation, and two separate signals at different wavelengths, respectively, as input by one channel, that is transmitted through fiber optic cables, and re-integrated with the WDM signal, received signal divided into 2 is to receive. Multiplexing and decoding it to MUX (Multiple Xor) the device is used.

[electricsketchbook]

Characteristics Features of DWDM

- The large-scale manufacture of fiber optics has made possible a reduction in costs and improved transmission characteristics of the fiber.
- Flat gain optical amplifiers to a certain range of wavelengths that line coupled with the fiber act as repeaters eliminating the need for regenerators.
- Integrated Filters smaller solid state and which can also be integrated into the same substrate along with other optical components.
- New photo detectors and laser sources producing integration allowing more compact designs.
- Multiplexers and demultiplexers based optical passive optical diffraction.
- Filters selected wavelengths, which can be used as optical multiplexers.
- The optical add-drop multiplexers (OADM) technology have enabled DWDM networks can be implemented in various types.
- The optical components of connection (OXC), which can be implemented with different manufacturing technologies, and have made possible purely optical switching.

[Rasdasa]

DWDM technology requires specialized optical devices based on the properties of light and optical properties, electrical and mechanical properties of semiconductors. Among these optical devices include optical transmitters, ADC and OXC.

The conventional single-mode fiber can transmit in the range of 1,300 nm a1.550. absorbing the wavelengths of 1340 to 1440 nm. WDM systems using wavelengths in the two possible ranges (from 1,300 nm to 1.34o 's1.440 to 1,550 nm). There are special fibers allow the transmission at all wavelengths between 1530 and 1,565 nm without absorption. However, not all optoelectronic components work with the same efficiency at all wavelengths.

[leight]

DWDM systems employ the latest advances in optical technology to generate a large number of wavelengths in the range near 1550 nm in the ITU-T recommendation G.692 defines 43 channels in the range of 1530 to 1565 nm with a 100 GHz spacing, each channel will carry OC-192 traffic at 10 Gbps. However, every day go to market systems with more channels. A 40-channel DWDM system at 10 Gbps per channel provides an aggregate speed of 400 Gbps.

Currently, commercial DWDM systems features 16 - 40 and 80 channels and is expected to market the next 128-channel systems. The systems with 40 channels have a channel spacing of 100 GHz, which have 80 channels have a spacing of 50 GHz frequency spacing This indicates the proximity of the channels together. A channel does not use only one wavelength, each channel has a certain bandwidth around the central wavelength, each band is separated from the next by a guard band area several GH, so it seeks to avoid possible overlap or interference between adjacent channels.

[Zoe]

Experts on the organization of optical communication networks note dthat the WDM technology lacks many of the constraints and technological difficulties inherent in TDM. To increase bandwidth, instead of increasing the transmission rate in a single composite channel, as implemented in the TDM, WDM technology to increase the number of channels (wavelengths) used in transmission systems. Increasing bandwidth by using WDM technology is carried out without the costly replacement of the optical cable. Application of WDM technology allows you to rent not only the optical cables or fiber, but also individual wavelengths, ie to implement the concept of "virtual fiber". For a single fiber at different wavelengths can simultaneously transmit a variety of applications - cable TV, telephony, Internet traffic.

[Icarusul]

Application of WDM technology eliminates additional cable laying in the existing network. Even if the future value of fiber will decrease due to the use of new technologies, fiber-optic infrastructure (paved fiber and fixed equipment) will always cost quite expensive. For its effective use must be able to for a long time to increase network capacity and change the set of services without replacing the optical cable. WDM technology provides such an opportunity.