Optical Power Meters – Workings explained

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Optical Power Meters – what are they?

An Optical Power Meter is a device with a calibrated sensor for measuring the display and an amplifier.

The sensor is typically a photodiode chosen for specific power levels and wavelengths.

The display screen of the device shows the set wavelength and the measured optical power.

Optical Power Meter
Power Meter


The most common applications for an optical power meter are:

  • Measurement of the absolute power in the given fiber optic signal. For the utilization of this application it is recommended that the device is appropriately calibrated at the corresponding wavelength.
  • For measuring the margin of the optical power
  • For measuring the optical loss in the given fiber along with a combination of the right source of stable light. Being that it is a relative test, accurate wavelength calibration is not a specific requirement, until two or more optical power meters are getting utilized for distance issues.

Using an Optical Power Meter & Light Source Together

The OPM device is used along with a light source to enable measuring of the signal loss in a fiber optic cable or the fiber optical channel.

The source of light is known to launch into one single end of a fiber optic cable. The optical power meter is typically connected to the other extreme end of the fiber optic cable. This method is used for measuring the optical power that has been received at the other end.

Optical Power Meter and Laser Source
Power Meter and Laser Source

The source of light can be an LED (Light Emitting Diode) or an optical laser that has been designed to be a part of the test set. Alternatively, the equipment for the communication of light wavelength can also be utilized as the light source.

As optical fiber loss tends to vary significantly with the wavelength selected, the optical power meter should be set for testing the same wavelength being utilized.

Furthermore, we recommend that the respective test should be carried out by making use of the same wavelength as the one that you tend to use when it comes to the equipment for light wavelength communication.

For example: if the wavelength of the equipment being tested is operating at (has a value of) 1310nm, the light source, as well as the optical power meter, is expected to be set to the testing value of 1310nm.

Optical Power Meter
1310nm Power Meter


In conclusion, an Optical Power Meter is an invaluable tool when it comes to testing. Make the most of the high-end optical power meters. Also, you need to make special considerations when you are testing with the help of the WDM network.