Erbium Doped Fiber (Unpumped) - Agilent Technologies 86038B User Manual

Erbium Doped Fiber (Unpumped)

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• PDL and DGD may be present due to polarization
dependence of the filter wavelength or if a circulator is
included
Measurement Tips
• If the group delay ripple is to be measured, it is necessary to
select a small enough modulation frequency and wavelength
interval to resolve the ripple. Since too wide smoothing will
also hide the ripple, it is better to use a low IF bandwidth if
necessary to reduce the noise.
• The swept mode offers very small wavelength intervals and
high measurement speed. The step mode may take an
unacceptable amount of time if the wavelength step is very
small and the wavelength range is large.
• When measuring in step mode in cases where resolving group
delay ripple is not required, select a modulation frequency
and wavelength step appropriate to the maximum expected
level of dispersion.
• The use of curve fits is likely to be useful in this application.
The markers can be used to limit the fit to the relevant
wavelength range. The deviation spectrum, the difference
between the measured data and the fit, can be displayed to
show the ripple.
• The component may also be characterized in terms of optical
phase ripple. Since the phase increases linearly with optical
frequency when there is no dispersion, the deviation from a
quadratic curve fit with respect to frequency, over the
channel width, is a good basis for determining ripple when a
fixed channel dispersion is desired.
Characteristics
• High loss (up to 10's of dB's)
• Low dispersion (very slight change in group delay over
wavelength)
• Wide wavelength range of interest
• Little if any fine group delay structure
Agilent 86038B Photonic Dispersion and Loss Analyzer, Second Edition