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Table Of Contents
Metro Regional Multi-Service Ring DWDM
Extending ONS 15454 Reach Distance
Applications
The Cisco ONS 15216 EDFA1 provides bandwidth-on-demand to extend DWDM links by hundreds of kilometers. This manual describes how to install and operate the ONS 15216 EDFA1, which is a DWDM-enabling technology for multiservice ring DWDM networks. The ONS 15216 EDFA1 is part of the Cisco ONS 15216 metro regional DWDM product line that includes red and blue terminal filters, a one-channel and two-channel optical add/drop multiplexer (OADM), and an optical performance manager (OPM).
The ONS 15216 EDFA1 is a C-band EDFA that has constant gain control, gain-flatness, transient suppression, and low-noise figure optimized for metro DWDM applications. These features enable the ONS 15216 EDFA1 to add/drop optical signals from a span in a DWDM network without degrading of the other optical signals in the same span.
Bandwidth-On-Demand
The ONS 15216 EDFA1 uses gain-control technology, which is the ability to keep the amplification per wavelength constant at all times as wavelengths are added/dropped from an optical fiber. Every wavelength in an ONS 15216 EDFA1, regardless of number, is guaranteed to be amplified by 23 dB. Any number of wavelengths can be amplified, as long as the total input power of all wavelengths is between -29 dBm and -6 dBm. Unlike previous generations of EDFAs, the ONS 15216 reconfigures itself rapidly to ensure constant gain and gain flatness.
Metro Regional Multi-Service Ring DWDM
Using the Cisco ONS 15216 product family you can build ring-based, multiservice DWDM systems using the Cisco ONS 15454 platform. DWDM systems that incorporate these two product families enable you to scale rings of up to 400 km in circumference. At each of the add/drop sites, a service provider can drop wavelengths to provide a variety of IP/data and TDM services. The Cisco ONS 15216/ONS 15454 solution provides not only a cost-effective method to create the multiservice environment, but also aggregates and grooms that traffic onto efficiently-packed wavelengths which are then carried around the DWDM ring.
Extending ONS 15454 Reach Distance
The Cisco ONS 15216 EDFA1 can be used in conjunction with the ONS 15454 to increase reach distance if the link loss between nodes in a metro network is greater than 15 dB. The ONS 15216 EDFA1 can be used as a booster amplifier immediately following the transmitter, as an in-line amplifier at an intermediate site, or as a pre amplifier just before the receiver.
ONS 15216 EDFA1 Operation
The ONS 15216 EDFA1 consists of a few meters of coiled erbium-doped fiber pumped by a high-power semiconductor laser operating at 980 nm. Amplification occurs when energy from the pump laser is transferred via the erbium-doped fiber to incoming optical signals in the 1550 nm window. Each optical signal leaves the ONS 15216 EDFA1 two hundred times brighter than when it arrived. Figure 1-1 is a block diagram of the ONS 15216 EDFA1.
Figure 1-1 ONS 15216 EDFA1 Block Diagram
Key Features
The ONS 15216 EDFA1 has the following key features:
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Constant gain of 23 dBm ± 1.25 dBm
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Constant Gain Mode
Constant amplification per wavelength is important for bandwidth-on-demand wavelength services. As wavelengths are added/dropped from an optical fiber, small variations in gain between channels in a span can cause large variations in the power difference between channels at the receivers. The ONS 15216 EDFA1 enables bandwidth-on-demand services by guaranteeing that every wavelength is amplified by 23 dB, regardless of the number of wavelengths being amplified.
Constant gain mode is achieved using an automatic control circuit that adjusts pump power when changes in input power are detected. The ONS 15216 EDFA1 operates in constant gain mode by default, but because other operating modes can be required, the EDFA can also be set to operate in any one the following modes:
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Gain Flatness
Figure 1-2 illustrates the importance of the ONS 15216 EDFA1's gain-flattening filter. With the first fiber (a), channels having equal power going into a cascaded network of amplifiers have vastly different powers and optical signal-to-noise ratio (SNR) at the output—without a gain flattening filter. In contrast, with the second fiber (b), the EDFAs reduce this effect by introducing a gain-flattening filter within each amplifier
Figure 1-2 Gain Flattening Filter
Transient Suppression
Transients in the performance of EDFAs are inevitable whenever the number of signals or the relative power of signals change. The amount of time required by an amplifier to recover from a change indicates the suitability of the amplifier for add/drop applications.
Low Noise
Noise increases whenever a gain occurs in an optical system. The predominant source of noise in EDFAs is Amplified Spontaneous Emission (ASE). The ONS 15216 EDFA1 has a low-noise figure of < 6.0 dB.
Posted: Sun Apr 2 03:13:33 PDT 2006
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