DWDM ZTE optical power debugging
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Optical Power Debugging
in the DWDM System
Reference Points in the DWDM System
So
So
OAC So So
OTS
Si
So
OTS
Si
Si
OMS
OCH
Si
Si OAC
Content
Purpose of Optical Power Debugging
Basic Formulas
Optical Power Calculation
Optical Power Debugging Purpose
We have 3 Purposes:
1. Make each channel has the same the optical
power in the transmission.
2. Make the OA working in the Best State.
3. Make the OTUR working in the Best State.
Optical Power Debugging Purpose
1.
Make each channel has the same the optical
power in the transmission.
In the transmission, the output power from OA
cannot be as high as we want, so the limited optical
power should be allotted to each channel equally.
After demultiplexing, each receiver can get the same
optical power.
Optical Power Debugging Purpose
Continue:
If In the receiving
end:
O
D
U
Over loading
OTUR
Client
Side
OTUR
Under sensitivity
Control the difference between any two waves to less
than 3dB. The less difference the better. Fl
atn e
ss
Optical Power Debugging Purpose
2.
Make the OA working in the Best State.
OA has three working state:
Over-Saturated State;
Saturated State;
This is the best working state.
Under-Saturated State;
Optical Power Debugging Purpose
3.
Make the OTUR working in the Best State.
10G
PIN
APD
0~-14dBm
Best: -6dBm
-9~-21dBm
Best: -12dBm
Optical Power Debugging Purpose
OTUT Output Power:
10G
OTUT or OTUG (EA or LD)=-1~ -5dBm
Content
Purpose of Optical Power Debugging
Basic Formulas （（（（
Optical Power Calculation
Basic Optical Power Balancing Calculation
P λ1 P λ2 P λ3
PN=Pλ1+Pλ2+Pλ3+…+PλN (mW)
PN=P1+P1+P1+…+P1 (mW)
unit
Because Pλ1=Pλ2=…=PλN = P1
=N×P1 (mW)
10lgPN=10lg(N×P1)
=10lgN+10lgP1
P λN
Because 10lgPN (mW) =PN (dBm)
10lgP1 (mW) =P1 (dBm)
PN=10lgN+P1
PN=10lgN+P1 (dBm)
备备备备备备备备nonlinear effect
Content
Purpose of Optical Power Debugging
Basic Formulas
Optical Power Calculation
Basic Optical Power Calculation
PIN
-0.5dBm
ch1
┇
TS2C
TS2C LT
LT
λ5
2220
2520
BA
PA
λ1
ODU40
ch5
λ1
OMU40
Input
TS2C
TS2C LT
LT
TS2C
TS2C LR
LR
┇
λ5
TS2C
TS2C LR
LR
ch1
Output
ch5
Line loss = 20dB
Insertion loss = 7dB
Insertion loss = 7dB
The Maximum Capacity of this DWDM system is 10G╳40Chs.
Now, there are only one traffics in it.
Question:
Where and what attenuation the attenuators should be added in the system?
lg40=1.6, lg5=0.7
Basic Optical Power Calculation
PIN
-0.5dBm
ch1
TS2C
TS2C LT
LT
λ5
2220
2520
BA
PA
λ1
ODU40
ch5
┇
OMU40
Input
TS2C
TS2C LT
LT
λ1
TS2C
TS2C LR
LR
ch1
Output
┇
λ5
TS2C
TS2C LR
LR
ch5
Line loss = 20dB
Insertion loss = 7dB
Insertion loss = 7dB
1. Before OMU: Optical power for each channel is the same.
2. Before OA: OA works in the best state.
3. Before TS2C LR: Receiver works in the best state.
Basic Optical Power Calculation
PIN
-0.5dBm
ch1
┇
TS2C
TS2C LT
LT
λ5
2220
2520
BA
PA
Line loss = 20dB
IL = 7dB
Pin Pout
P40out=P1out+10lg40
P1out=P40out-10lg40
=20-16
=4(dBm)
λ1
ODU40
ch5
λ1
OMU40
Input
TS2C
TS2C LT
LT
TS2C
TS2C LR
LR
┇
λ5
IL = 7dB
TS2C
TS2C LR
LR
ch1
Output
ch5
Basic Optical Power Calculation
PIN
-0.5dBm
ch1
TS2C
TS2C LT
LT
λ5
2220
2520
BA
PA
IL = 7dB
Line loss = 20dB
λ1
ODU40
ch5
┇
OMU40
Input
TS2C
TS2C LT
LT
λ1
┇
λ5
IL = 7dB
PoutOMU PInOBA
Attenuation=P1outOMU-P1inOBA
=(-0.5-7)-(4-22)
=10.5(dB) nearly 10dB
Before OBA:
TS2C
TS2C LR
LR
10dB attenuation
TS2C
TS2C LR
LR
ch1
Output
ch5
Basic Optical Power Calculation
PIN
-0.5dBm
ch1
┇
TS2C
TS2C LT
LT
λ5
2220
2520
BA
PA
IL = 7dB
Line loss = 20dB
PoutOBA
PAfter Line=P1outOBA-Line Loss
=4-20
=-16(dBm)
PAfter Line
λ1
ODU40
ch5
λ1
OMU40
Input
TS2C
TS2C LT
LT
TS2C
TS2C LR
LR
┇
λ5
IL = 7dB
TS2C
TS2C LR
LR
ch1
Output
ch5
Basic Optical Power Calculation
PIN
-0.5dBm
ch1
┇
TS2C
TS2C LT
LT
λ5
2220
2520
BA
PA
IL = 7dB
Line loss = 20dB
Pin
P40out=P1out+10lg40
P1out=P40out-10lg40
=20-16
=4(dBm)
λ1
ODU40
ch5
λ1
OMU40
Input
TS2C
TS2C LT
LT
┇
λ5
IL = 7dB
Pout
TS2C
TS2C LR
LR
TS2C
TS2C LR
LR
ch1
Output
ch5
Basic Optical Power Calculation
APD
-0.5dBm
ch1
TS2C
TS2C LT
LT
λ5
2220
2520
BA
PA
IL = 7dB
Line loss = 20dB
λ1
ODU40
ch5
┇
OMU40
Input
TS2C
TS2C LT
LT
λ1
Attenuation=PAfter Line-P1inOPA
=-16-(4-25)
=5(dB)
Before OPA:
┇
λ5
IL = 7dB
PAfter Line PInOPA
5dB attenuation
TS2C
TS2C LR
LR
TS2C
TS2C LR
LR
ch1
Output
ch5
Basic Optical Power Calculation
PIN
-0.5dBm
ch1
TS2C
TS2C LT
LT
λn5
2220
2520
BA
PA
IL = 7dB
Line loss = 20dB
λ1
ODU40
ch5
┇
OMU40
Input
TS2C
TS2C LT
LT
λ1
Attenuation=P1outOPA-P1inODU
=4-7
=-3(dB)
Before ODU:
3dB attenuation
备备备 saturated output 备备备备
┇
λ5
IL = 7dB
PoutOPA PinODU
TS2C
TS2C LR
LR
TS2C
TS2C LR
LR
ch1
Output
ch5
Question?
Just now, we use one channel optical power in
the attenuation calculation.
What happened if we use 4 channels or 40
channels optical power in the calculation?
Basic Optical Power Calculation
Basic Optical Power Calculation
Basic Optical Power Calculation
CARD TYPE
SLOT
PORT IN - PORT
OUT
Attenuator
Insertion Loss
Channel Gain
Poutch
(IL)
(G)
(1 Channel)
dB
dB
dBm
TS2C
0-1-13/0-1-14/
0-2-13/0-2-14
-
-
-0.50
OMU40
0-1-6
CHxx - OUT
7.00
-
-7.50
SOP1
0-1-15
Tin - Tout1/Tout2
3.00
-
-10.50
SEOBA2220
0-1-20/0-2-20
IN - OUT
7
-
21.50
4.00
Basic Optical Power Calculation
A:
B:
