Anritsu Company VectorStar ME7848A-0140 Manuale di avvio rapido - Pagina 12
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4. Making Opto-electronic Component Measurements
4.
Making Opto-electronic Component Measurements
The typical measurement scenario with the ME7848A/E opto-electronic network analyzer system is to analyze
the conversion behavior of E/O or O/E devices or to study the RF envelope behavior for signals passing through
O/O components. All of these measurements are done from an RF perspective by the VNA with the optical
carrier (provided by the laser) acting as a parameter. Much more measurement information is available in the
VectorStar Calibration and Measurement Guide, 10410-00318, (with an entire chapter devoted to this
particular measurement class) but some salient points will be summarized here.
• The VNA calibration establishes reference planes (for insertion loss and phase, group delay, and
reflection) at the ends of the RF cables (or wherever the calibration was performed). Thus a
measurement of, for example insertion loss, the structure in
conversion loss of the E/O and O/E modules and the optical interconnect.
• To study individual components (i.e., an E/O converter of interest is to be inserted into the path), the
other components need to be de-embedded. There are many ways to start this process, but for reasons of
maximum accuracy and traceability, the MN4765B O/E module is delivered with a characterization file
describing its behavior). After the non-DUT components have been de-embedded, the residual response
is that of the device of interest.
• Most transmission measurements in this class are relative (e.g., to get at 3 dB or 10 dB bandwidth) but
absolute responsivities can be extracted using the known optical power and the known absolute
responsivities of the system components.
• Measurements on 2- and 4-port VectorStar VNAs are possible that allow the coverage of differential and
dual devices. These measurements are not covered in detail here since the ME7848A/E system
definitions are 2-port-based, but upgrades are possible and more information is available in the
VectorStar Calibration and Measurement Guide, 10410-00318.
E/O Measurements
This is the simplest class where the E/O DUT is connected to the MN4765B calibration module (and patch cord
losses are usually neglected) and the MN4765B is de-embedded. In the VNA software is a dialog like that
shown below where the configuration is entered and the .s2p file describing the MN4765B is loaded. When this
dialog is exited, the calibration coefficients will be modified by the de-embedding file so the resulting
measurement represents the response of the DUT. If input match of the E/O device is of interest, a direct S11
measurement (assuming the configuration of
A screenshot of an E/O measurement dialog on VectorStar is shown in
configured and the characterization data for the O/E device are loaded and, upon hitting 'Done', the calibration
coefficients are updated on the instrument to de-embed the O/E characteristics.
QSG-12
Figure
3; no de-embedding needed) will accomplish the task.
PN: 10410-00777 Rev. C
Figure 2
will represent the combined
Figure
4. The measurement is
ME7848A/E QSG