Picosecond Electrooptic Sampling and Harmonic Mixing in GaAs

Abstract

Electro-optic sampling is a powerful technique for exploiting the capabilities of modern mode-locked laser systems to make high speed electronic measurements. Using ultrashort light pulses to probe the electric fields of microstrip transmission lines deposited on LiNbO₃ and LiTaO₃, VALDMANIS et al. [1,2] demonstrated an electro-optic sampling system capable of resolving picosecond and subpicosecond rise-time photoconductive switches. KOLNER et al. [4,5] utilized a similar system to characterize photodiodes exhibiting bandwidths of 100 GHz. In both cases, a hybrid connection between the device under test and the electro-optic transmission line was required. VALDMANIS et al. [6] and MEYER and MOUROU [7] have shown that by placing an electro-optic crystal in contact with the circuit under test, picosecond waveforms could be measured without a hybrid connection. Although these techniques have demonstrated impressive results, they potentially compromise the true device response by reactive loading of the transmission line systems. This occurs due to 1) the fundamental mode mismatch between similar transmission lines on different dielectrics, 2) parasitic reactances associated with the bonding wires between the two transmission line systems or 3) capacitive loading of a transmission line by close proximity to the sampling crystal.