Specifications

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Cisco ONS 15216 EDFA Operation Guide

78-12818-01

Chapter 1 Applications

ONS 15216 EDFA1 Operation

• Low-noise figure of < 6.0 dB

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:

• Constant-pump current mode

• Constant-pump power mode

• Constant-output power mode

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.

Gain

Flattening

Filter

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