F I N A L D R A F T - C I S C O C O N F I D E N T I A L
1-3
Cisco ONS 15216 EDFA2 Operations Guide
78-16033-01
Chapter 1 Applications
Key Features
The ONS 15216 EDFA2 has the following key features:
•
Adjustable constant gain of 13 to 22 dB
•
Gain flattening < 2 dB (peak to valley)
•
Transient suppression
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Low noise figure of < 7 dB at –5 dBm input
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Simple Network Management Protocol (SNMP) MIBs
•
Transaction Language 1 (TL1)
1.3.1 Constant Gain
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 dB, no
matter how many wavelengths are being amplified.
Constant gain 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 Temperature Compensated
mode by default, but since there may be applications where other operating modes may be required, the
ONS 15216 EDFA2 can be set to operate in any one the following pump control modes:
•
Constant Gain Temperature Compensated mode
•
Constant Output Power mode
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Constant Pump Current mode
•
Constant Pump Power mode
1.3.2 Gain Flattening
Figure 1-3
illustrates the effect of the gain flattening filter in the ONS 15216 EDFA2. Fiber (a) in the
figure shows a set of channels with equal powers being input to a cascaded network of amplifiers that
produce vastly different power levels and optical signal-to-noise ratios (OSNR) at the output. In contrast,
fiber (b) shows how the EDFAs effectively reduce this effect by introducing a gain flattening filter within
each amplifier.
Figure 1-3
Gain Flattening Filter
Gain
Flattening
Filter
a
b
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