HP 86037B, Instruction Manual

Page: 17 / 204

1-11
Quick Start
Measuring Grating Devices
Measuring Grating Devices
In this section, you’ll learn how to make measurements on grating based
devices such as Bragg fiber gratings. It is recommended that you do not skip
this section. Since the HP 86037B, by default, is set for making measurements
on fiber devices, before measuring grating devices, perform the following
steps:
1 Select
Absolute Group Delay
Measurement
in the
Grating Related
Parameters
area in the main
window. (By default, relative
group delay is measured.)
Refer
to “Absolute Group Delay Measurement” on page 2-14 .
In addition to selecting absolute group delay, this selection turns off the
review data window’s curve fit selection. Although, curve fitting is a standard
method used to reduce the effects of noise when measuring fiber based
devices, there is currently no standard for grating based devices. You can, of
course, export the data and apply your own corrections.
2 Set the
Test Modulation Frequency
to the
Manual
setting. Refer to “CD/Gain Meas
command” on page 2-15 to configure this
setting.
For details on determining the proper RF test modulation frequency, refer to
“Setting the RF modulation frequency” on page 1-12 .
3 Use larger wavelength steps during test setup normalization compared to
during the measurement. This reduces overall test time.
Since patch cords used during normalization have very low dispersion, the
system is able to interpolate accurate values for use with grating measure-
ments. For example, if you are measuring a grating with 5 nm wavelength
range, you could use 1 nm steps during normalization and 1 pm steps during
measurements.
4 Expect large jumps in measured dispersion.