Application of Optical Add-Drop Multiplexer

What’s the Optical Add-drop Multiplexer?

The optical add-drop multiplexers (OADM) are used in wavelength-division multiplexing systems for multiplexing and routing different channels of light into or out of a single mode fiber (SMF). This is a type of optical node, which is generally used for the construction of optical telecommunications networks. An OADM may be considered to be a specific type of cross connect cabinet.

A traditional OADM consists of three stages: an optical demultiplexer, and optical multiplexers, and between them a method of reconfiguring the paths between the optical demultiplexer, the optical multiplexer and a set of ports for adding and dropping signals. The optical demultiplexer separates wavelengths in an input fiber onto ports. The reconfiguration can be achieved by a fiber patch panel or by optical switches which direct the wavelengths to the optical multiplexer or to drop ports. The optical multiplexer multiplexes the wavelength channels that are to continue on from demultiplexer ports with those from the add ports, onto a single output fiber.

Principles of OADM technology

General OADM node can use four port model (Figure 1) to represent, includes three basic functions: Drop required wavelength signal, Add rumored signal to other wavelengths pass through unaffected. OADM specific network process is as follows: WDM signal coming from the line contains mangy wavelength signals into OADM’s “MainInput” side, according to business required, from many wavelength signals to selectively retrieved from the end (Drop) output desired wavelength signal, relative to the end from the Add the wavelength of the input signal to be transmitted. While the other has nothing to do with the local wavelength channels directly through the OADM, and rumored signals multiplexed together, the line output from the OADM (Main Output) Output.

OADM node technical classification

Optical drop multiplexer network technologies can be divided into two types, fixed optical drop multiplexer (Fixed OADM, FOADM) and reconfigurable optical drop multiplexer (Reconfigurable OADM, ROADM).

Fixed Optical Drop Multiplexer (FOADM)

FOADM to filter as the main component, and its function is fixed to join or retrieve certain light wavelengths. General common FOADM can be divided into three types, namely Thin Film Filter type (TFF type), Fiber Bragg Grating (FBG type) and integrated planar Arrayed Waveguide Gratings (AWG type).


Thin Film Filter (TFF FOADM)

TFF FOADM using thin film between the filtering effect of the different refractive index.

Fiber Bragg Grating (FBG FOADM)

FBG FOADM use of fiber Bragg grating filtering effect, with two circulator can become FOADM.

Arrayed Waveguide Gratings (AWG FOADM)

AWG FOADM gererally used in semiconductor fabrication processes, the integration of different refractive index material is formed on a flat substrate in a planar waveguide, when different wavelength light source is incident through the couping after the import side, due to take a different path length, while the different phase delay caused by different wavelengths and thus produce certain wavelengths in the export side to form a constructive or destructive interference, making waves in the export side, the different wavelengths will follow the design on a different channel to reach, and thus achieve FOADM function.

Reconfigurable Optical Add/Drop Multiplexer (ROADM)

ROADM can always be adjusted with the distribution network to add and drop wavelength, which reconstruct the network resource allocation, the flexibility to meet the requires of modern urban network, so a flexible ROADM features, plus optical switch substantial advantage, making the current fastest growing ROADM based optical switches based ROADM (switch based OADM). ROADM mainly be the optical switch, multiplexer and demultiplexer composed, Switch-based OADM, mainly divided into Wavelength independent switch array and wavelength selection switch.

Wavelength independent switch array

Type 1: Wavelength independent switch array

Wavelength selective switch

Type 2: Wavelength selective switch

All kinds of optical drop multiplexer performance comparison

optical drop multiplexer performance

OADM network applications

WDM ROADM optical fiber suitable for different network environments

OADM network applications

OADM in the metropolitan network development tendency

1. Arbitrary choice must be retrieved, adding wavelength, the wavelength can take advantage of the limited resources, the node can be retrieved with the need to do to join the adjustment of the signal wavelength, and has a remote control functions. This can provide dynamic reconfiguration of optical communications network capable ROADM will be connected to the backbone network critical devices. And FOADM is used for wavelength demand network access will be smaller parts to reduce costs. Furthermore, ROADM use to all kinds of Tunable Laser, unable Filter, or wavelength selective optical switches and other components.

2. Must be able to convert incompatible wavelength suitable for the backbone network will be transmitted wavelengths. Therefore, OADM be combined with wavelength conversioin Transponder or other functional components.

3. Must be able to compensate for the node to make acquisistion, adding such action energy loss. Therefore, OADM optical amplifiers must be combined with functional components.

4. Wavelength signals related specifications, such as: the signal to noise ratio (S/N), the energy balance between the signal wavelength, etc., are required to meet network requirements. Therefore must be combined OADM variable optical attenuators (VOA), dispersion compensation module (DCM) and other components.

What Are Optical Multiplexers?

An optical multiplexer, basically, a device, an input can be routed to the many different output, usually is 16. It utilizes fibr optic technology, is usually controlled by use of software and a totator block, and has an optical path that is actually coupled through several COL-UV/VIS collimating lenses. So, this is basically what a fiber optic multiplexer is…but what exactly do these devices do, and what are they used for? Well, that is a good question, and here is some information that might help you. Although it is hard to tell you all about optical multiplexer in an article, here are some things that may help you better understand the complex operation of equipment.

1 Channel Video to Fiber SM FC 20km Optical Video Multiplexer

Basically, optical multiplexer using one side of a fiber optic cable, so a lot of things can send information in the same line. It is like a giant multiple input connector that allow several signal input, and then send a fiber optic cable. This information travels along this wire until, it comes into contact with a demultiplexer, which is like another attachment at the end of the cable that again splits up the signals and sends them on their way.

One of the most obvious uses for a optical multiplexer is the fact that it saves a lot money. Therefore, by placing one end of the multiplexer, a signal separator in another company can save a lot of money in the fiber optic cable.

To some extent, the resulting network information, and the way to travel, can be compared to a large highway. This large highway connections may be two very big city, in the morning, there may be a lot of traffic on a highway to go to other city. However, although all use the same highway, traffic is it does not actually come from the same place, also is not all in the same place.

On the highway traffic slowly from a different side of the road in a city, it will exit in the same way when it arrives at destination. In this way, the illustration is a lot like a fiber multiplexer/demultiplexer system, with the cars being the information, the cities being the multiplexers, and the freeway being the fiber optic cable.

This is a very basic method to describe the optical multiplexer how to work, and i hope it can help you to understand. It is not a too hard to master the concept of, even if the fiber is still a technology, can make people don’t use it all the time. The best way to learn about fiber optic cable is to either research it, or to actually work with it in a network or a system. A lot of different industries now make use of the speed with which fiber optic can deliver information. Light travels a lot faster than electric signals, after all. Optical Multiplexer is popularly with telecommunication operator and suitable in business for communication operator, government and kinds of entities. It is one of the most transmission equipment in point-point fiber optic network. Typical optical multiplexers are Video & Data & Audio Multiplexers, PDH Multiplexer.