EXFO FTB-5500B PMD Analyzer - Manual (Page 112)

Using Third-Party Broadband Light Sources
104 FTB-5500B
Compliance Criteria
The rms width of the auto-correlation determines the basic uncertainty
of the interferometric method (Equation 4 on page 105). The smaller
the rms width of the auto-correlation, the smaller the basic uncertainty.
If the uncertainty is critically required to be equal to or smaller than the
specified uncertainty using dedicated EXFO sources, the rms width of
the auto-correlation,
, must be smaller than .
Equation 2
In the particular case of a Gaussian-shaped spectrum with no ripple,
Equation 2 corresponds to
Equation 3
(30.0 nm @ 1550 nm, 21.5 nm @ 1310 nm)
If criterion 2 is not met, the instrument will still operate normally, but
the uncertainty specification will change according to the uncertainty
formula given on the next page (Equation 4 on page 105).
It is useless to ask for a general specification regarding ripples or
FWHM: it is impossible to precisely quantify the condition via these
parameters. The auto-correlation interferogram is the relevant function
to examine, through its rms width.
σ
0
" 0.1 ps ∼
σ
0
0.1 ps ≤
FWHM 3.75 THz ≥