Extinction ratio
![Eye diagram showing an example of two power levels in an OOK modulation scheme which can be used to calculate extinction ratio. P1 and P0 are represented by (binary '1') and (binary '0') respectively.](/Images/godic/202501/12/On-off_keying_eye_diagram.svg0957.png")
In telecommunications, extinction ratio (re) is the ratio of two optical power levels of a digital signal generated by an optical source, e.g., a laser diode. The extinction ratio may be expressed as a fraction, in dB, or as a percentage. It may be given by