The transmitter makes use of a laser source and two cascaded Mach-Zehnder modulators to achieve a high extinction ratio. The ERM2xx Extinction Ratio Meters measure the polarization extinction ratio (PER) and the polarization angle of polarization-maintaining (PM) fibers. These easy-to-use benchtop devices are useful in alignment applications such as connectorization of PM fibers or pigtailing of laser diodes with PM. The Extinction Ratio measurement for NRZ waveforms measures how well available laser power is converted to modulation power. Mathematically it is the ratio of the logic one level to the logic zero level. Although specifications are defined by industry standards and test method-ologies loosely described, historically it has been. Fiber-optic transceivers used in high-speed digital communications systems must comply with a stringent set of performance criteria.
