Absolute power measurements at wavelengths of 1300 nm and 1550 nm with a cryogenic radiometer and a tuneable laser diode

An experimental set-up designed for the calibration of near-infrared detect ors against a cryogenic radiometer, using a tuneable laser diode as source, is described. A complete characterization of the cryogenic radiometer has been performed at the Institute de Fisica Aplicada (IFA, Madrid), at wavele ngths of 1300 nm and 1550 nm. Two different secondary standards, an electri cally calibrated pyroelectric radiometer and an InGaAs-based integrating-sp here radiometer, have been calibrated with relative uncertainties of less m w 10(-3) at these wavelengths.