What is Extinction Ratio?

What is Extinction Ratio?

The ratio of the average power levels of the logic 1 level (High) to the logic 0 level (Low) of an optical signal. See the on-line Help, Automatic Measurements for more detailed discussion.

Also see Troubleshooting Automatic Measurements for examples of automatic measurements. It also has comments on compensation ("self-calibration"), Dark Level compensation and Extinction Ratio measurements.