Archived — Fiber Optic Technology

The Agilent 71451B/11896A Swept-Wavelength PDL Test System provides a high-speed method for measuring PDL across a 1250 to 1600 nm wavelength range. Measurement data examples are shown in Figures 10 and 11. This measurement uses the Agilent 71451B Optical Spectrum Analyzer to monitor changes in DUT insertion loss versus wavelength. Automatically swept wavelength coverage is provided by the built-in, white-light source and monochromator of the Agilent 71451B Option 002 (see Figure 12). The test signal’s polarization state is automatically  adjusted using the Agilent 11896A Polarization Controller (included as part of the Agilent 71451B Option 003). PDL calculations are done automatically

The Agilent 8509/11896A Power Max./Min. PDL test system is a semi-automatic, single-wavelength PDL measurement  system. It provides a PDL value and absolute maximum and minimum power values and polarization information (see Figure 8). The Power Max./Min. PDL measurement method is similar to the Agilent 8153A/11896A power meter method discussed  in this document. During this measurement, the Agilent 8509A or 8509B Polarization Analyzer monitors the average output power and state of polarization. PDL Markers are automatically placed on the Poincare sphere (see Figure 8) to indicate the points at which optical power maximum and minimum occur. The respective Stokes parameters for

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. Measurement procedure 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

Table 2 shows the typical PDL measurement capabilities of each method compared to possible performance requirements. The power and PDL ranges shown in this table will be referred to throughout this document. Use this table to decide which measurement method is most appropriate for a specific application. Table 2. PDL measurement method performance comparison Among the three methods offered, the Power Meter Method offers the highest single-wavelength PDL measurement accuracy. This method is well suited for general-purpose applications. The Power Max./Min. Method provides single-wavelength PDL data plus polarization state information about which relative states of polarization create maximum and minimum

The Agilent 11896A adjusts polarization and not power and is an important part of a PDL test system. Its optical fiber loop design, shown in Figure 2, provides all states of polarization (see Figure 3) with extremely small optical insertion-loss variations (0.004 dB) over a 1250 to 1600 nm spectral range. This performance combination maximizes measurement accuracy for power sensitive PDL measurements (see Figure 4). The Agilent 11896A adjusts the polarization of a transmitted signal as it passes through the internal four-fiber-loop assembly. Each loop’s dimensions are optimized to approach a quarter-wave retarder response over the controller’s specified wavelength range.