What does 850nm mean in an optical power meter

850nm refers to the nominal wavelength of light, commonly used in multimode fiber, which an optical power meter is set to measure accurately.What 850nm MeansIn fiber optics, 850nm denotes the wavelength of the light signal, measured in nanometers (nm), which is in the near-infrared spectrum . This wavelength is commonly used for short-distance transmission over multimode fiber (MMF), such as within data centers or office buildings, typically supporting distances up to a few hundred meters . The choice of wavelength affects how light propagates through the fiber, including attenuation, dispersion, and overall link performance .Relevance to Optical Power MetersAn optical power meter (OPM) measures the power of an optical signal, and its sensor is calibrated for specific wavelengths . Setting the meter to 850nm ensures that the photodiode detector accurately interprets the light intensity at that wavelength. Using the wrong wavelength setting can lead to incorrect readings because the detector's responsivity varies with wavelength . Silicon (Si) detectors, for example, perform well at 850nm but are less accurate at longer wavelengths like 1550nm .Practical ImplicationsShort-reach applications: 850nm is ideal for intra-building or data center links where multimode fiber is used .Calibration: The optical power meter must be set to 850nm to match the light source for accurate power measurement .Detector choice: Si detectors are commonly used for 850nm due to their good sensitivity in this range, while other detectors like InGaAs are more suitable for longer wavelengths . In summary, 850nm in an optical power meter indicates the wavelength of light the meter is measuring, which is critical for accurate readings, especially in multimode fiber systems used for short-distance optical communication .