Routing Device - Agilent Technologies 86038B User Manual

Narrowband Filter or DWDM Wavelength Routing Device
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• Swept mode gathers a large number of points to smooth,
taking advantage of the smoothing function. However, the
step mode allows taking and averaging a large number of
samples at each wavelength, also reducing the noise. Try
both modes to find the best trade-off of accuracy and
measurement speed.
Characteristics
• Very narrow wavelength range or ranges
• Rapid changes of measurement parameters with wavelength
• Dispersion and PDL often associated with filter edges
• Fine in-band structure of some attributes, possibly including
group delay ripple.
• Steep filter slopes
• High rejection outside the passband
Measurement Tips
The combination of narrow passband and fine group delay
structure requires high wavelength resolution measurements
• Swept mode should be used to measure many points with
small increment, like 10 pm, in a reasonable time, including
the polarization dependence. The high wavelength resolution
also usually require using a small modulation frequency. Try
500 MHz. To reduce noise, the low IF bandwidths, like 30 Hz
may be required. Further noise reduction could be obtained
by using a smaller increment, like 1 pm and then Gaussian
smoothing to a 10 pm resolution.
• Select the Phase Dynamic Accuracy (PDA) correction when
performing a swept or stepped normalization for filter
testing, if GD at high loss is also of interest. This correction
reduces the degree to which the large variations in device
loss with wavelength are translated into small errors in
group delay.
• Amplitude ripple and GD ripple can be analyzed by using an
appropriate Curve Fit to the data and then displaying the
"deviation".
Agilent 86038B Photonic Dispersion and Loss Analyzer, Second Edition