Preparing for Measurement
3-21
IM AQ6380-02EN
1
2
3
4
5
6
App
Index
Clearing the Resolution Calibration Value
5.
Tap the
Initialize
. The calibration value will be cleared.
Explanation
Typically the filter response of an optical spectrum analyzer is not rectangular, and thus the
resolution bandwidth differs slightly from the equivalent noise bandwidth. This difference
becomes prominent especially when the wavelength resolution is high (e.g., 0.05 nm or less). The
resolution calibration function measures the equivalent noise bandwidth at each resolution setting
and internally sets the resolution bandwidth to the result. The resolution bandwidth appears in
parentheses in each of the resolution soft keys on the resolution screen.
The resolution bandwidth accuracy affects the results of noise measurements and the results of
optical power measurements of wideband light sources. In detail, the resolution bandwidth is used
when the following analysis and computation functions are executed.
• WDM analysis
• EDFA-NF (optical amp gain, NF measurement)
• Power analysis
• OSNR and total power of DFB-LD analysis
• Total power of FP-LD analysis
• Total power of LED analysis
• Power spectral density markers, Integrated power markers
3dB
Before resolution calibration
Peak value
3 dB bandwidth = Resolution bandwidth
The number displayed on the soft key
Filter response of the optical
spectrum analyzer
After resolution calibration
Equivalent noise bandwidth = Resolution bandwidth
The equivalent noise bandwidth is the width of the
equivalent rectangle formed by keeping the spectrum
area constant.
Filter response of the optical
spectrum analyzer
3.6 Resolution Calibration
