It is an instrument specifically used for measuring the strength of optical signals. It converts optical signals into electrical signals through a photoelectric sensor and then displays the power value in units of decibels-milliwatts (dBm) or watts (W). Typically, it allows for power measurements only with a relatively low bandwidth, and will display, for example. Optical power meters are a key element in the optimization and maintenance of such optical networks and of their components. In this article, learn: What is an optical power meter? An optical power meter (OPM) measures the power levels of light signals in devices that transmit data or power using. An optical power meter (OPM) is a device used to measure the power in an optical signal.