The Agilent 8153A/11896A power meter-based PDL test system provides high-accuracy, single-wavelength, PDL data. During this measurement, the Agilent 8153A Light wave Multimeter monitors output power variations and displays the PDL values (see Figures 5). The polarization state of the test signal is continually and automatically adjusted using the Agilent 11896A Polarization Controller shown in Figure 6.
This 11-step procedure enables single-wavelength PDL measurements to be performed on an Agilent 8153A/11896A power meter-based PDL measurement system.
The Agilent 8153A Light wave Multimeter should be equipped with the MinMax automatic measurement feature before beginning this procedure. Contact an Agilent representative to upgrade an Agilent 8153A Light wave Multimeter with this feature if “MinMax” does not appear in step #4 below.
Agilent 8153A settings (1/2):
1. Press Chan to activate the power sensor channel. Channel B is assumed.
2. Press Param several times until the measurement averaging time T appears in the lower-right side of the display. Enter a 20 ms averaging time by using the Modify up-and-down keys.
3. Press Mode.
4. Press Record (under the Applications section of the front panel) several times until MinMax-C appears. If the “C” in MinMax-C does not appear press Edit and then the Modify up-and-down keys until CONT appears. Press Edit again to return to the main menu. (Contact an Agilent representative for an Agilent 8153A firmware upgrade if “MinMax” does not appear).
5. Press Exec.
Agilent 11896A settings (1/1):
6. Press SCANRATE.
7. Use the far right knob to select SCAN RATE: 5 and press ENTER. Refer to the Uncertainty Analysis of this measurement for information about scan rate selection.
8. Press AUTOSCAN.
9. When 0:10 (10 seconds) appears in the scan time indicator, press Manual. This stops the polarization scan. 10 seconds is the recommended polarization scan time (also referred to as measurement time) for PDL values of <3.0 dB. Refer to the Uncertainty Analysis section of this measurement for a discussion of recommended scan times for PDL values greater than 3.0 dB.
Agilent 8153A settings (2/2):
10. The measurement is complete. PDL data is displayed in the upper right-hand corner of the Agilent 8153A display (see Figure 5).
11. To begin the next measurement, connect a DUT as shown in Figure 6, press Exec two times and return to step #8.
PDL measurement uncertainty for the Agilent 8153A/11896A PDL measurement system is the sum of the measurement system’s inherent uncertainty (values shown in Table 3) and the uncertainty created by the measurement’s finite scan time relative to the PDL of the test device (see Table 4). Below is an explanation of these terms and an uncertainty calculation.
It is assumed that the DUT output power range is between +3.0 to –50 dBm and the PDL value is <3.0 dB, as shown in Table 2. Actual system performance will vary depending upon the individual performance of the specific equipment in the system. Refer to the Appendix for additional ways to ensure maximum PDL measurement accuracy from a given PDL measurement system.
Inherent PDL measurement system uncertainty contribution:
Individual elements in a PDL measurement system randomly combine to create a system uncertainty contribution value as shown in Table 3.
PDL measurement time and scan rate relationships for uncertainty contribution:
Various PDL measurement conditions may require different power measurement averaging times in order for the Agilent 8153A Light wave Multimeter to achieve optimum performance. Table 4 shows the relationships between the averaging time, the Agilent 11896A Polarization Controller scan rate and the overall polarization scan time. All scan time recommendations are based on a DUT PDL of <=1.0 dB and a 5% scan time uncertainty contribution. The percent-PDL uncertainty equations shown in Table 4 are provided for estimating scan time (also known as measurement time) uncertainty contributions for a given scan time. Figure 7 shows how percent-PDL uncertainty decreases with increased scan time.
Example of uncertainty calculation:
Below is an example for calculating the worst-case uncertainty for an Agilent 8153A/11896A PDL measurement of 0.3 dB. Values shown are derived from information in Tables 3 and 4.