Specifications

1-3
Cisco ONS 15216 EDFA2 Operations Guide
78-13908-02
Chapter 1 Applications
Key Features
Key Features
The ONS 15216 EDFA2 has the following key features:
• Adjustable constant gain of 13 to 22 dBm
• Gain flattening < 2 dBm
• Transient suppression
• Low noise figure of < 7 dB at –5 dBm input
• Simple Network Management Protocol (SNMP) MIBs
Constant Gain Mode
Constant amplification (gain) per wavelength is important for ensuring that variations in power between
channels at the receivers is minimized. 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 EDFA2 enables bandwidth-on-demand services by
guaranteeing that every wavelength is amplified by a value that can be set between 13 and 22 dBm, no
matter how many wavelengths are 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 EDFA2 operates in constant gain mode by default,
but since there may be applications where other operating modes may be required, the ONS 15216
EDFA2 can also be set to operate in any one the following modes:
• Constant pump current mode
• Constant pump power mode
• Constant output power mode
Gain Flattening
Figure 1-3 illustrates the importance of the gain flattening filter in the ONS 15216 EDFA2. As shown in
the figure, with fiber (a), a set of channels with equal powers is input to a cascaded network of amplifiers
that have vastly different power levels and optical signal-to-noise ratios (OSNR) at the output–without
a gain flattening filter. In contrast, with fiber (b), the EDFAs effectively reduce this effect by introducing
a gain flattening filter within each amplifier.