Electro-optic signal measurement

Abstract

Electro-optic probes which are adapted to be placed in the fringe field from electrical signals propagating on conductors (which may be conductors of an integrated circuit) and which modulate optical pulses passing therethrough, for example by modulating the polarization of the light in accordance with the Pockels effect, utilize thin bodies of electro-optic material, such as a single crystal of GaAs in a manner to reduce physical damage to the probe and to the circuit and to precisely locate the probe in the field of the signal being measured, such as adjacent to the conductor of interest. The electro-optic material that is used may also be implanted with high energy ions of low Z materials (e.g. hydrogen or oxygen) so as to create charge trapping sites and to reduce the photo conductivity of the semiconductive electro-optic material sufficiently that the dielectric relaxation time (where photo current through the material reduces by ) is less than the duration of the optical pulses without eliminating the electro-optic (e.g. Pockels) effect. Charge carriers are trapped and cannot screen the electric field lines due to the electrical signal being measured which extend between the charge trapping sites where sufficient undamaged electro-optic material remains and enables the field and therefore the signal corresponding thereto to be measured.