72
Testing Optical Couplers
Measuring Optical Coupler Characteristics
Explanation of the Results
If this is your setup, you have measured the following parameters:
Coupling Ratio
CR
A/B
(%) = Out
1/2
/ (Out
1
+ Out
2
)
CR
A/B
(dB) = – 10 Log [Out
1/2
/ (Out
1
+ Out
2
)]
Splitting Ratio
SR
A/B
(%) = Out
1/2
/ Out
2/1
SR
A/B
(dB) = – 10 Log [Out
1/2
/ Out
2/1
]
Insertion Loss
IL
A/B
(dB) = 10 log [Out
1/2
/ P ref]
Excess Loss
EL (dB) = – 10 log [(Out
1
+ Out
2
) / P ref]
Directivity
DIR
A/B
(dB) = – 10 log [In
2
/ P ref]
Figure 4-5
Connection Scheme for Optical Couplers
1
2
1
2
In
1
(P ref)
In
2
Out
1
(Head A)
Out
2
(Head B)
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