High-speed electrical sampling by fs photoemission

Abstract
We propose and demonstrate a new method for contactless sampling of high-speed electrical signals, by spectral analysis of photoelectrons emitted when a signal-carrying conductor is illuminated by ultrashort light pulses. We present time-resolved measurements of sub-ns electrical signals on a gold transmission line on GaAs using three-photon photoemission induced by 80 fs visible laser pulses, and we discuss the temporal resolution of these measurements. This method is applicable to devices and circuits on any semiconductor.