Overview Wavelength division multiplexing (WDM) remains the prevailing technology for adding flexibility and functionality to today’s optical networks. By transmitting signals at different wavelengths through the same fiber, WDMs can multiply transmission capacity, improve testing, and transmit voice services over video. Value-Added Module (VAM) systems equipped with WDM technology are used in a variety of applications to reduce operational expenses and increase revenue opportunities. Increasing Transmission Capacity Fiber overlays can be expensive and time consuming. In order to deliver broadband services, many service providers are integrating WDM modules into the network to gain capacity without deploying additional fiber. Adding a WDM on each end of a circuit instantly doubles the bandwidth on a fiber pair. A typical application features one fiber for the transmit direction and another fiber for the receive direction. (See Figure 1.) In most cases, legacy equipment will operate at 1310 nm. It is simply a matter of incorporating a WDM module at each end of the span and adding new equipment transmitting at 1550 nm. In a higher capacity network, transmission signals operating at 1310 nm and 1550 nm are then simultaneously transmitted over the same fibers. (See Figure 2.) This enables the existing fiber in the plant to double capacity. The WDM approach also enables providers to work with existing electronic equipment, which proves to be much more cost-effective than incorporating new DWDM modules or additional fibers into the network. WDM Module Value-Added Module (VAM) System application note Figure 1 Original Network 1310 FOT 1310 1310 Single Fiber Near End Far End Tx Rx 1310 FOT Tx Rx 5/02 • 1226582 WDM Module Value-Added Module (VAM) System WDM Module 2 www.adc.com • +1-952-938-8080 • 1-800-366-3891 Nonintrusive Testing WDM modules introduce out-of-band testing by enabling networks to operate and test at different wavelengths. A network operating at 1310 nm can be tested at 1550 nm and networks operating at 1550 nm can be tested at 1625 nm. Out-of-band testing is a simple, effective solution that is easy to implement into the network. (See Figure 3.) Often, access to the customer or co-location site is restricted. With WDMs, a signal at a different wavelength from the normal traffic is injected at the near end of a system and travels to the far end, where it is looped back via a WDM at the demarcation point and returns to the original end. This allows full bi- directional OTDR (optical time domain reflectometer) testing on a live transmit/receive pair to be conducted from a central location. The service provider reduces operational expenses by not rolling a truck to the far end or disrupting customer’s service for testing purposes. Figure 2 Higher Capacity Network with WDMs 1550 Near End 1310 FOT Tx Rx WDM Module WDM 1550 FOT Tx Rx WDM Module WDM Far End 1310 FOT Tx Rx WDM Module WDM 1550 FOT Tx Rx WDM Module WDM 1310 Single Fiber Single Fiber 1550 1310 Figure 3 Continual Nonintrusive Testing Single Fiber Single Fiber 1550 Near End 1310 FOT Tx Rx WDM Module WDM 1550 Test Box Tx Rx WDM Module WDM Far End 1310 FOT Tx Rx WDM Module WDM Tx Rx WDM Module WDM 1310 1550 1310 1550 Test Box 5/02 • 1226582 WDM Module 3 www.adc.com • +1-952-938-8080 • 1-800-366-3891 Value-Added Module (VAM) System WDM Module Figure 4 REAR FRONT Connectorized Pigtail Adapter Port Adapter Port OPTICAL COMPONENTS Connectorized Pigtail (3 mm Jacketed) Bare Pigtail (2 mm Jacketed) Transmitting Voice Services over Video When video requirements arise, a WDM network offers a cost-competitive option compared to additional fiber deployment. In most applications, a 1310 nm fiber route has already been established to accommodate traditional voice grade service. By using a 1550 nm video transmitter, both video and voice co-exist on the same fiber pairs, but are independently delivered to the subscriber. Value-Added Functionality ADC’s plug-in VAM modules can be purchased with most industry standard singlemode connectors. Module inputs and outputs can be made via adapter, pigtail or bare fiber depending on customer requirements. (See Figure 4.) Various combinations of all front access to input/output ports or rear access to both input/output ports are also available. All bare fiber options use 2 mm jacketing. The variety of module configurations allows the provider the opportunity to determine the number and type of optical connections necessary depending on whether a cross-connect or interconnect arrangement is used in the fiber cable management scheme. ADC Telecommunications, Inc., P.O. Box 1101, Minneapolis, Minnesota USA 55440-1101 Specifications published here are current as of the date of publication of this document. Because we are continuously improving our products, ADC reserves the right to change specifications without prior notice. At any time, you may verify product specifications by contacting our headquarters office in Minneapolis. ADC Telecommunications, Inc. views its patent portfolio as an important corporate asset and vigorously enforces its patents. Products or features contained herein may be covered by one or more U.S. or foreign patents. An Equal Opportunity Employer 1226582 5/02 Original © 2002 ADC Telecommunications, Inc. All Rights Reserved Web Site: www.adc.com From North America, Call Toll Free: 1-800-366-3891, Ext. 73475 • Outside of North America: +1-952-938-8080 Fax: +1-952-917-3237 For a complete listing of ADC’s global sales office locations, please refer to our web site. . with WDMs 1550 Near End 1310 FOT Tx Rx WDM Module WDM 1550 FOT Tx Rx WDM Module WDM Far End 1310 FOT Tx Rx WDM Module WDM 1550 FOT Tx Rx WDM Module WDM. Near End 1310 FOT Tx Rx WDM Module WDM 1550 Test Box Tx Rx WDM Module WDM Far End 1310 FOT Tx Rx WDM Module WDM Tx Rx WDM Module WDM 1310 1550 1310 1550