  In this paper we describe a nonlinear imaging method employed to spatially
map the occurrence of constrictions occurring on an electrically-stressed gold
nanowire. The approach consists at measuring the influence of a tightly focused
ultrafast pulsed laser on the electronic transport in the nanowire. We found
that structural defects distributed along the nanowire are efficient nonlinear
optical sources of radiation and that the differential conductance is
significantly decreased when the laser is incident on such electrically-induced
morphological changes. This imaging technique is applied to pre-determined the
location of the electrical failure before it occurs.
