Commonly called out in optical telecommunication standards, ER is a measure of modulation depth, and can be used for example as a figure of merit of an optical modulator. This article. The Extinction Ratio defines how distinct the “on” (logic 1) and “off” (logic 0) states of an optical transmitter are, making it a direct indicator of signal quality in optical transceivers. P1 and P0 are represented by (binary 1) and (binary 0) respectively. In telecommunications, extinction ratio (re) is the ratio of two optical power levels of a digital. This white paper explains some of the benefits of highly accurate ER measurements in both 10 GbE (Ethernet), with its relatively low ER requirement, and in SONET/SDH, and the methodology that supports consistent, accurate ER result. Although specifications are defined by industry standards and test method-ologies loosely described, historically it has been. The average transmit optical power refers to the optical power output by the light source at the transmit end of the optical module under normal working conditions, which can be considered as the luminous intensity. This indicator is critical to evaluating the performance of optical modules because.