How Much Do You Know About OADM

The OADM, or optical add drop multiplexer, is a gateway into and out of a single mode fiber. In practice, most signals pass through the device, but some would be “dropped” by splitting them from the line. Signals originating at that point can be “added” into the line and directed to another destination. An OADM may be considered to be a specific type of optical cross-connect, widely used in wavelength division multiplexing systems for multiplexing and routing fiber optic signals. They selectively add and drop individual or sets of wavelength channels from a dense wavelength division multiplexing (DWDM) multi-channel stream. OADMs are used to cost effectively access part of the bandwidth in the optical domain being passed through the in-line amplifiers with the minimum amount of electronics.

OADMs have passive and active modes depending on the wavelength. In passive OADM, the add and drop wavelengths are fixed beforehand while in dynamic mode, OADM can be set to any wavelength after installation. Passive OADM uses WDM filter, fiber gratings, and planar waveguides in networks with WDM systems. Dynamic OADM can select any wavelength by provisioning on demand without changing its physical configuration. It is also less expensive and more flexible than passive OADM. Dynamic OADM is separated into two generations.

A typical OADM consists of three stages: an optical demultiplexer, an optical multiplexer, 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 cross connection 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 demultipexer ports with those from the add ports, onto a single output fiber.

Physically, there are several ways to realize an OADM. There are a variety of demultiplexer and multiplexer technologies including thin film filters, fiber Bragg gratings with optical circulators, free space grating devices and integrated planar arrayed waveguide gratings. The switching or reconfiguration functions range from the manual fiber patch panel to a variety of switching technologies including microelectromechanical systems (MEMS), liquid crystal and thermo-optic switches in planar waveguide circuits.

CWDM and DWDM OADM provide data access for intermediate network devices along a shared optical media network path. Regardless of the network topology, OADM access points allow design flexibility to communicate to locations along the fiber path. CWDM OADM provides the ability to add or drop a single wavelength or multi-wavelengths from a fully multiplexed optical signal. This permits intermediate locations between remote sites to access the common, point-to-point fiber message linking them. Wavelengths not dropped, pass-through the OADM and keep on in the direction of the remote site. Additional selected wavelengths can be added or dropped by successive OADMS as needed.

HTFuture provides a wide selection of specialized OADMs for WDM system. Custom WDM solutions are also available for applications beyond the current product designs including mixed combinations of CWDM and DWDM.

HTFuture aim to be your Reliable Partner for different kinds of Compatible transceiver (QSFP28, QSFP+, SFP, XFP, SFP+ etc) | OTN optical transmission system|DWDM Mux Demux|OADM | OTU | EDFA | NMS | DCM | OLP | OBP etc| More information, welcome to contact Ivy, contact Ivy. Email: sales6@htfuture.com Skype: live:sales6_1683

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CWDM Network: Technology Overview and Common Applications

Fiber exhaust is an inevitable problem constantly faced by carriers since the demand for higher speed bandwidth never ceases. The ever-improving wavelength division multiplexing (WDM) technology nowadays is increasingly used to boost network capacity, enabling carriers to deliver more services over their existing fiber infrastructure. CWDM, as one form of the mature WDM technologies, is a perfect fit for access networks and metro/regional networks. This article addresses the CWDM fundamentals and its common applications, and how CWDM helps to maximize network capacity effectively.

CWDM Technology at a Glance

Coarse wavelength division multiplexing (CWDM) came into prominence as a cost-effective alternative to maximize network capacity in the access, metro and regional network segments. It gains in more popularity in area with a relatively moderate traffic growth due to its simple deployment and low cost. ITU-T G.694.2 defines 18 wavelengths for CWDM transport ranging from 1270 to 1610 nm, spaced at 20 nm apart. But 8 wavelength in the 1470–1610nm band is mostly used since there exist high attenuation in the 1270–1450 nm band. This technology shines out in access network deployments by obtaining the advantages of flexible add-drop capacity and network design simplicity.

Common Applications of CWDM

After going through the basics of CWDM technology, this section will further explain its common applications. CWDM is primarily deployed in two areas: metropolitan and access networks. Let’s see how they could benefit from applying it.

Fiber Exhaust Relief

Fiber exhaust appears to be a severe problem that carriers endeavor to solve, especially for some metropolitan networks where data traffic increases continuously. Adding CWDM to the original optical network presents a cost-efficient and simple approach to this problem. In this case, carriers can add new services over a existing single optical fiber, while not interrupting service for existing customers. This solution is ideally suited for carriers that desires to increase the already installed network capacity without new fiber construction.

Enterprise LAN and SAN Connection

When interconnecting geographically dispersed Local Area Networks (LANs) and Storage Area Networks (SANs), CWDM rings and point-to-point links offer an optimum option. It is beneficial to integrate multiple Gigabit Ethernet, 10 Gigabit Ethernet and Fiber Channel links over a single fiber for CWDM point-to-point applications or for ring applications.

Adoption in Metro Networks With Lower Cost

4 channel CWDM system offers an ideal solution for smaller metro/regional markets which demand for moderate traffic growth. This configuration can expand the available capacity four times over an existing network, enabling less deployment cost than the commonly adopted 8 channel system. Meanwhile, the scalability of this 4 channel system also allows carriers to upgrade to 8 channel systems when the need occurs.

Central Office to Customer Premise Interconnection

Coarse WDM system is also well-fitted for metro-access applications such as Fiber to the Building (FTTB). Let’s take the most widely used 8 channel CWDM network for example, it is capable of delivering 8 independent wavelength services from the Central Office (CO) to multiple business offices located in the same building.

Combining With PON

Passive Optical Network (PON) is a point-to-multipoint optical network to deliver bandwidth to the last mile. It is cost-effective because it uses passive devices (splitters for example) instead of expensive active electronics. The issue exists in PON is that the amount of bandwidth they can support is rather limited. Since CWDM serves to multiple bandwidth, when combining it with PON, each additional lambda becomes a virtual point-to-point connection from a central office to an end user. If one end user in the original PON deployment needs his own fiber, adding CWDM to the PON fiber creates a virtual fiber for that user. Once the traffic is switched to the assigned lambda, the bandwidth taken from the PON is now available for other end users, so the access system can maximize fiber efficiency.

Conclusion

CWDM has clearly become the preferred method for increasing the bandwidth of metro/regional and optical access networks quickly, simply and at lowest cost. And it has proven to be sufficiently robust and reliable for upgrading the optical network to accommodate future growth. Hope this article could help to get a better understanding of coarse WDM technology.

HTFuture can provide you the full range of CWDM DWDM products that you need. If there is any inquiry, just let me know please.

Ivy: sales6@htfuture.com Skype: live:sales6_1683

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