Near-field second harmonic imaging of lead zirconate titanate piezoceramic

Near-field optical microscopy has been used to image variations in local optical second harmonic generation (SHG) from the surface of lead zirconate titanate (PZT) piezoceramic. As PZT ceramic is a strongly scattering medium. SHG occurs in the thin layer near the surface of the ceramic. Thus, individual crystalline grains and grain boundaries located near the surface are the main features visible in the images. In general, this technique allows us 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 been observed. This enhancement is believed to result from local cavity resonances.