Electro-absorption sampling at terahertz frequencies in III-V semiconductors

We review recent advances in the development of a new sampling technique for ultra high-speed electrical signals. It is based on the electro-absorption phenomena in semiconductors (Franz–Keldysh effect). We demonstrate that it is usable up to the terahertz range. The theory is exposed and we show two practical set-ups. The first uses the semiconductor substrate (internal sampling). The second uses a small semiconductor probe bonded on the circuit (external sampling). In this last case, the theoretical temporal resolution is about 200 fs. In practice, we measure a risetime of about 500 fs with 60 dB of dynamic range. To cite this article: J.-F. Lampin et al., C. R. Physique 9 (2008).