Absolute Intensity Measurements of CW GHz and THz Radiation Using Electro-Optic Sampling

We report on traceable and spatially resolved intensity measurements of continuous wave (CW) radiation at 100 GHz using laser-based electro-optic (EO) sampling. Traceability of the laser-based setup is achieved by comparison of the EO measurements with measurements using a calibrated radiometer. The uncertainty budget of the EO measurements is discussed in detail. Although we just perform intensity measurements at ~100 GHz, the EO setup can be used for characterization of CW sources over a very broad frequency range from a few gigahertz to ~2.5 THz.