BLOCK DIAGRAM & OPERATION
ChromaFlex CPA EDFA – Hardware Interface Manual
4-1
ATX
Confidential & Proprietary
BLOCK DIAGRAM & OPERATION
4. Block Diagram & Operation
The following block depicts the optical signal flow and control bus through the CF-CPA EDFA module.
Figure 4-1: CF-CPA EDFA Module Block Diagram
The CF-CPA is a Constant Power Amplifier therefore the composite output power remains the same over the specified range
of optical input level. Thus the EDFA composite gain, gain per wavelength and per wavelength output power will change
with a change in the number of wavelengths or composite input power applied to the EDFA to maintain a constant output
power. The CF-CPA is primarily utilized as a headend launch amplifier applications with a fixed number of wavelengths.
Optical signals in the 1530 nm to 1562 nm range are connected to the front panel optical input LC connector and first pass
through an input coupler/isolator. The optical channels within the spectrum are then connected to the Erbium Doped Fiber
& multiplexer gain stage where a pump laser is multiplexed with the input signal resulting in an amplified output signal.
The output of the gain stage is connected to the output side coupler/isolator. The input and output coupler provides a
reference signal to the micro-processor control circuitry which adjusts the pump laser and gain stage to maintain a constant
composite output power with changes to the composite input power. The micro-processor also provides status monitoring
signaling to the ChromaFlex chassis. The amplified output signal may be connected to an optional filter or circulator type of
Express Port for inserting additional optical channels or extracting channels. A filter is typically utilized if the optical channels
are separated in different bands and a circulator is utilized if channels in the upstream direction are interleaved with the
downstream signals passing through the EDFA. Circulator example, utilizing downstream wavelengths of (20,21,22,23)
upstream 24, downstream (25,26,27,28) upstream 29. The upstream channels 24 and 29 would be directed to the R-EP
port. Note that the circulator is directional and cannot be utilized for combing purposes, only upstream extraction. A 5%
coupler test point is provided at the output of the EDFA.
CHAPTER 4:
IN
TP
5%
Coupler
+G
Filter or
Circulator
1%
Coupler
Optional
1,2,4-way
OUT 1
OUT 2
OUT 3
OUT 4
TP
R-EP
CF-CPA-00*
Opt. IP TP Variable Gain
Opt. EP
Opt. OP TP
IN
TP
5%
Coupler
+XX
Filter or
Circulator
1%
Coupler
Opt. OP TP
Opt. EP
OUT
TP
R-EP
CF-GCA-XX*
Circulator EP
Filter EP
Opt. IP TP Fixed Gain
