The optical power meter measured

A reading of -15 on an optical power meter typically means the optical signal is 15 dB below 1 milliwatt, indicating a relatively low power level in the fiber optic system.What the Reading MeansOptical power meters (OPMs) measure the power of light in fiber optic systems, usually in dBm, which is a logarithmic unit relative to 1 milliwatt . A reading of -15 dBm corresponds to:Power in milliwatts: P=10(−15/10)≈0.0316 mW This is a low but typical signal level for fiber optic links, especially over longer distances or through multiple connectors and splices .Implications for Fiber Optic SystemsSignal strength: A negative dBm value indicates the signal is weaker than 1 mW. -15 dBm is generally sufficient for short to medium fiber runs, but may require amplification or careful system design for longer distances .Loss measurement: If measuring loss, a more negative reading compared to the source indicates attenuation in the fiber. For example, if the source outputs 0 dBm and the meter reads -15 dBm, the fiber link has 15 dB of loss .System performance: Most receivers in fiber optic networks can operate with signals in the range of -10 dBm to -30 dBm, depending on the technology and wavelength used. Therefore, -15 dBm is within a normal operating range for many systems .Practical ConsiderationsWavelength setting: Ensure the OPM is set to the correct wavelength (e.g., 1310 nm or 1550 nm for single-mode fiber) to get an accurate reading .Connector quality: Poor connections or dirty connectors can reduce measured power, making the reading more negative.Calibration: Optical power meters should be calibrated to a traceable standard to ensure accuracy . In summary, a -15 dBm reading indicates a low but usable optical power level, and understanding it in the context of your fiber link helps assess signal quality, loss, and system performance.