All-States Method for PDL or PER Synchronous Polarization Scrambler
Application Notes
Polarization Scrambler and Stabilizer
Polarization controllers like the N7785C and N7786C can repeatably run long sequences of polarization states, synchronized to other instruments with triggering signals. The N7786C can also set and stabilize chosen polarization states. These can be used to improve accuracy measuring polarization dependent loss (PDL) or polarization extinction ratio (PER). The principles and programming are described in this note.
Standard PDL Measurement Methods
There are two general methods for measuring the polarization dependent insertion loss (PDL) of a fiberoptic component, which are standardized in the IEC document 61300-3-2 as the all-states method and the Mueller Matrix method. In the all-states method, the optical test signal to the device under test is varied through a sufficiently large sampling of all possible polarization states such that the relation between the maximum and minimum optical power measured at the device output represents the PDL with the necessary accuracy.