Agilent Technologies 86038A User Manual page 295

Dispersion Terminology Glossary
Chromatic Dispersion (CD)
In digital lightwave technology, pulse broadening caused by the variation
of group delay across the spectrum of the signal. Defined as the derivative
of the group delay with respect to wavelength and expressed in ps/nm.
See also "Chromatic Dispersion Coefficient" .
Chromatic Dispersion Coefficient
In the context of transmission fiber, the chromatic dispersion value divided
by the length of fibers in kilometers. Usually expressed in ps/km.
Coherence
A signal property related to 1/spectral width. Narrow spectra mean high
coherence, wide spectra mean low coherence. When low coherence
signals are separated and recombined, they interfere only if the path
lengths are nearly equal. High coherence signals interfere over large path
differences.
Correlation Length
In the context of long, mode-coupled optical fiber, the fiber length over
which the polarization state of the propagating signal becomes
uncorrelated relative to the input polarization state. Usually expressed in
meters.
Curve Fitting
Post-processing of the measurement trace data in which a model
mathematical curve is optimally fitted to the trace. The 86038A ODA
provides a default set of curve fitting functions for fiber test: quadratic, 3-
term and 5-term Sellmeier. Also provide is a linear curve fit that can be
applied to some components. The user can create and install new curve
fitting functions.
Distributed Feedback Laser (DFB)
Used as a source in high-speed fiber systems. Single line, narrow
linewidth.
Differential Group Delay (DGD)
The difference in group delay between the fast and slow polarization
modes of a fiber or device at a particular wavelength and temperature.
Degree of Polarization (DOP) Degree of Polarization. The fraction of
the optical power (intensity) that is polarized. Fiber coil polarization
controllers can manipulate this part of the light.
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Agilent 86038A Optical Dispersion Analyzer, Third Edition