A typical optical power meter consists of a calibrated sensor, measuring amplifier and display.
A traditional optical power meter responds to a broad spectrum of light, however, the calibration is wavelength dependent.
Optical power meters are available as stand-alone bench or handheld instruments or combined with other test functions such as an Optical Light Source (OLS), Visual Fault Locator (VFL), or as sub-system in a larger or modular instrument.
More advanced OLTS may incorporate two or more power meters, and so can measure Optical Return Loss.
The major semiconductor sensor types are Silicon (Si), Germanium (Ge) and Indium Gallium Arsenide (InGaAs).
Careful optical design is required to avoid significant accuracy problems when used with the wide variety of fiber types and connectors typically encountered.
Irrespective of power meter specifications, testing below about -50 dBm tends to be sensitive to stray ambient light leaking into fibers or connectors.
Therefore, achieving a good level of practical instrument accuracy and linearity is something that requires considerable design skill, and care in manufacturing.
With the increasing global importance in the reliability of data transmission and optical fiber, and also the sharply reducing optical loss margin of these systems in data centres, there is increased emphasis on the accuracy of optical power meters, and also proper traceability compliance via International Laboratory Accreditation Cooperation (ILAC) accredited calibration, which includes metrological traceability to national standards and external laboratory accreditation to ISO/IEC 17025 to improve confidence in overall accuracy claims.
In practice, such instruments usually achieve lower absolute accuracy due to the small detector diode, and for the same reason, may only be accurate when coupled with single-mode fiber.
Also, at low pulse repetition rates, some meters with data or tone detection may produce improper or no readings.
This unit is essentially a triple power meter, with a collection of wavelength filters and optical couplers.
Wavelength sensitivity of fiber optic power meter is a problem when using a photodiode for voltage current measurement.