Uncertainty in the calibration of a photodiode-type power meter due to the spectral width of a light source

The error due to the spectral width of a light source in the calibration of a photodiode-type power meter has been studied. Three types of photodiodes, namely, Si, Ge, and InGaAs, have been examined in the wavelength region 800-1650 nm. Theoretical calculations have shown that an error of more than 5% may arise with a Si or Ge photodiode in a specific wavelength region. The measured difference between two photodiode-type power meters agreed with the theoretically calculated value to 0.5%