Typical power levels measured by an optical power meter: Telecom transmitters: 0 to +10 dBm (1 to 10 milliwatts), Receivers: -30 dBm (1 microwatt) DWDM systems with fiber amplifiers: +10 to +20 dBm (10 to 100 milliwatts), Receivers: -20 to -30 dBm (1-10. Typical power levels measured by an optical power meter: Telecom transmitters: 0 to +10 dBm (1 to 10 milliwatts), Receivers: -30 dBm (1 microwatt) DWDM systems with fiber amplifiers: +10 to +20 dBm (10 to 100 milliwatts), Receivers: -20 to -30 dBm (1-10. Fiber Optic Measurement Units: "dB" and "dBm" Whenever tests are performed on fiber optic networks, the results are displayed on a power meter, OLTS or OTDR readout in units of “dB. ” Optical loss is measured in “dB” which is a relative measurement, while absolute optical power is measured in “dBm,”. Acceptable dB loss for fiber depends on the component you're measuring: a single mated connector pair should lose no more than 0. 75 dB, a fusion splice should stay under 0. 3 dB, and fiber cable itself loses between 0. 5 dB per kilometer depending on the type and wavelength. Please ensure you review your technical specification to see if it deviates from the values found in the cabling standards. However, it is important to note that the optimal dBm level can vary based on the specific fiber optic system and network requirements. When there's loss in a fiber optic system, the measured power is less than the reference power, resulting in a negative logarithmic value and a negative dB reading on the meter.