Near-field second harmonic imaging of lead zirconate titanate piezoceramic

Near-field optical microscopy has been used to image variations in local op tical second harmonic generation (SHG) from the surface of lead zirconate t itanate (PZT) piezoceramic. As PZT ceramic is a strongly scattering medium, SHG occurs in the thin layer near the surface of the ceramic. Thus, indivi dual crystalline grains and grain boundaries located near the surface are t he main features visible in the images. In general, this technique allows u s to determine the local poling direction of individual submicrometre-sized crystalline grains of ceramic by near-field SH imaging at different angles of incidence and polarization states of the fundamental excitation light. In some cases 'hot spots' of submicrometre size showing enhanced SHG have b een observed. This enhancement is believed to result from local cavity reso nances.