Tag: FWDM

Application of Optical Add/Drop Multiplexer CWDM/DWDM Module

What’s the CWDM/DWDM 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. 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.

OADM ModuleOADM Module Application of OADM

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).

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

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

OADM network applications

WDM ROADM optical fiber suitable for different network environments.

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.

Application of optical communication is still broad prospects

Once the Nortel global leader in fiber optic communications during the Internet bubble in 2000, the money in the acquisition of a large number of optical communications research and the production of small and medium enterprises, the industry has been criticized in the subsequent bankruptcy of Nortel. In fact, Nortel grasp of technology trends, the direction is right, unfortunately, Nortel too hasty, global demand for optical communication was not to such an extent.

But now the situation is very different compared with around 2000. The rapid development of mobile Internet and the widespread popularity of smart mobile terminal equipment, being a huge challenge to the global telecommunications network capacity, transmission speed. The era of “data flood peak to optical communication technology has always been known by the transmission bit of new development opportunities and a huge space. Optical communication technology not only did not fall behind, the contrary, the optical communication industry chain, from fiber optic cable system equipment, terminal equipment to optical devices, a critical period in the comprehensive technology upgrade.

The field of optical communication is a noteworthy event, the National Development and Reform Commission recently organizing the preparation of strategic emerging industries key products and services Guidance Catalogue, which in conjunction with the relevant departments, the optical communication technology and product responsibility and selected emerging industries of strategic focus products.

In fiber optics, including FTTx G.657 optical fiber, broadband long-distance high speed large capacity optical fiber transmission with G.656 optical fiber, photonic crystal fiber, rare earth doped fiber (including ytterbium doped fiber, erbium doped fiber and thulium doped fiber, etc.) the laser energy transmission fiber, and has some special properties of new optical fiber, plastic optical fiber, polymer optical fiber is fully finalists. The upgrade of the fiber optic technology, will bring the data transmission capacity, distance, quality leap.

In the field of fiber access equipment, passive optical network (PON), wavelength division multiplexer (WDM),OLT and ONU on the list. Optical transmission equipment, especially the line rate of 40 Gbit/s, 100Gbit/s large capacity (1.6Tb/s and abobe) DWDM equipment, reconfigurable optical bifurcation Multiplexer (ROADM) wavelength division multiplexing system ran cross-connect (OXC) equipment, large-capacity high-speed OTN optical transport network equipment as well as packetized enhanced OTN equipment, PTN packet transport network equipment also impressively. These products are “broadband China” works to promote a powerful weapon; both long-distance backbone network, metropolitan area network or access network even close to the user’s “last mile” of these products will come in handy.

The major products are classified as strategic emerging industries in the field of optical devices, high-speed optical components (active and passive). This is the core and foundation of the field of optical communication technology, device development, the improvement of integration, function enhancement can bring significantly reduce the cost of system equipment and provide a performance boost.

At the same time, the annual OFC / NFOEC (fiber-optic communications exhibition) will be held in late March in California. This event will showcase the latest technology and research progress of the global optical component modules, systems, networks and fiber optic products, represents a new trend of development of optical communication technology.

100G for ultra-high-speed network technology is the current OFC hot one. 2012 100G technology on a global scale backbone network level scale application of 100G optical network applications will rapidly expand with the 100G device further mature. In the same time, the industry has also increased efforts to develop the 100G optical modules, silicon photonics technology pluggable multi-source agreement 100G CFP MSA CPAK optical module has been available. Outside the backbone network, 100G MAN application is the current one of OFC discussion topic.

The rise of cloud computing brings data center construction boom, 100G technology in the data center is a popular data center for high-speed pluggable optical devices is also a hot topic. Experts believe that photonic technology has a key role to play in the large enterprise data centers, but this is only a start, the size of the new cloud computing data center such as a warehouse, with more than 100,000 servers carrying the computing and storage resources, the required network bandwidth than PB level. These data centers only optical communications technology in order to achieve VCSEL (vertical cavity surface emitting lasers) and multi-mode fiber has played an important role, and will continue to introduce new fiber optic communication technology.

Things You Should Know About Filter WDM

Wavelength-division multiplexing (WDM) is overtaking since the leading technology in point-to-point transmission links. One key method is a tunable optical filter. Important features of this type of filter include low insertion loss, narrow bandwidth, high sidelobe suppression, large dynamic range, fast tuning speed, a simple control mechanism, small size, and expense effectiveness. Filter WDM module will depend on Thin Film Filter (TFF) technology. The FWDM is extensively found in EDFA, Raman amplifiers, WDM networks and fiber optics instrumentation. The unit combines or separates light at different wavelengths in the wide wavelength range. Since FWDM series offer minimal insertion loss, low polarization dependence, high isolation and excellent environmental stability, perfect for very fast WDM network systems. It really is traditionally used in optical fiber systems:1310/1550nm, 1480/1550nm, 850/1310nm, 980/1550nm and 1310/1490/1550nm.

FWDM Main Features:

  •  Wide Operating Wavelength Range;
  •  Low Insertion Loss;
  •  Ultra Flat Wide Passband;
  •  High Channel Isolation;
  •  High Stability and reliability;
  •  Epoxy-free on Optical Path.
  •  FWDM Applications:
  •  Testing Instruments;
  •  FTTH Tri-Play System.

WDM is a method of combining multiple signals on lasers at various infared (IR) wavelengths for transmission along fiber optic media. Each laser is modulated by an impartial pair of signals. Wavelength-sensitive filters, the IR analog of visible-light color filters, are employed on the receiving end.

WDM is comparable to frequency-division multiplexing (FDM). But rather than going on at radio frequencies (RF), WDM is done inside the IR element of the electromagnetic (EM) spectrum. Each IR channel carries several RF signals combined by using FDM or time-division multiplexing (TDM). Each multiplexed IR channel is separated, or demultiplexed, in the original signals with the destination.

The usage of WDM can multiply the effective bandwidth of an fiber optic communications system with a large factor. However its cost should be compared to the choice of utilizing multiple fibers bundled in to a cable. A fiber optic repeater device referred to as erbium amplifier plans to make WDM a cost-effective long-term treatment for the bandwidth exhaustion problem.

DK Photonics offers a wide selection of WDM/CWDM/DWDM devices, like CWDM Mux/Demux, CWDM OADM, DWDM Mux/Demux, DWDM OADM, Filter WDM and so on. DK Photonics 1310/1490/1550 WDM devices based on thin-film filter technology are design to address the precise requirements from the FTTP market. Strong coating and passive device packaging capabilities feature these WDMs with excellent optical performance, good reliability and ultra-compact size.