Operating Basics
ORR24 Instruction Manual
9
If you connect fiber cores larger than 9
mm, the reference receiver may still
couple light, but the mismatch in core diameter will cause lower conversion gain
and high insertion loss.
Attenuating Optical Signals
When using the ORR24 as a reference receiver, it may be necessary to attenuate
the optical signals.
CAUTION.
To avoid damaging the optical input of the ORR24, attenuate optical
signals to less than 5 mW average power or 10 mW peak power at the wave-
length with highest relative responsivity.
For linearity and measurement accuracy, attenuate the peak-to-peak swing of
signal to within the specified performance of 200
mW
p-p
.
Example:
1. You want to look at an OC-48 eye-pattern signal whose average power
(un-attenuated) is about +2 dBm. The average optical power of the +2 dBm
signal is equal to 1584
mW.
2. For optical signals with a 50% duty cycle , the average power is
approximately one half of the peak-to-peak swing for high extinction ratio
signals. This means that the peak-to-peak value of the optical signal is
approximately
2 x 1584
mW = 3168 mW
p-p
3. To lower the signal to within the 200
mW range, the signal must be
attenuated by 3168
mW / 200 mW = 15.84; this is equal to about 12 dB of
optical attenuation.
To attenuate the optical signal to the proper level, use a Tektronix OA5002
Optical Attenuator.
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