Zte Unitrans ZXMP M600 Technical Instructions page 72

ZXMP M600 (V1.0) Technical Manual
3.
A.10 Return Loss
A.11 Side Mode Suppression Ratio
A.12 Minimum Extinction Ratio
The Rayleigh reflection exerts least influence, while Stokes reflection only
occurs at the excitation threshold.
Influence on the system
Large reflection may seriously affect the transmission system and produce bit
error, delay and pulse expansion in the signals. If the reflection produces noise,
it will lower the signal-noise ratio and affect the normal operation of the system.
It describes the reflection restriction index of the interface that is used to restrict
the reflection strength in the optical interface on an optical channel.
Optical Return Loss (ORL) is defined as the ratio between the power of the
forward optical signals and the power of the reverse optical reflection at a
specific point.
It can be calculated through the following formula:
IL=10 lg (P /P ) (dB)
s R
In the formula, P indicates the power of forward optical signals while P
s
indicates the power of the reverse optical reflection.
It is the ratio between the major mode optical power of the optical source in full
modulation (the peak value) and the maximum side mode optical power
(secondary peak value) under the worst reflection condition. It is only valid to a
laser that supports direct modulation.
It indicates the ratio between the average high (on) optical power and the
average low (off) optical power in full modulation under the worst reflection
condition.
A-8
R