Optical Power Meter: Measures the optical power in both 'on' and 'off' states to calculate the extinction ratio. One parameter, extinction ratio, is used to describe optimal biasing conditions and how efficiently available laser transmitter power is converted to modulation power. Although specifications are defined by industry standards and test method-ologies loosely described, historically it has been. In telecommunications, extinction ratio (re) is the ratio of two optical power levels of a digital signal generated by an optical source, e.