GHZ polarization dynamics in ferroelectric thin films

We present results from experiments which measure the local dielectric resp onse of ferroelectric thin films driven by microwave-frequency electric fie lds. The repetition rate of a mode-locked Ti:Sapphire laser is used to gene rate a microwave drive signal that is phase-locked to an optical probe puls e and applied to the ferroelectric thin film. The induced polarization chan ge in the ferroelectric film is measured stroboscopically via the electro-o ptic effect, polarization images are acquired by scanning the laser beam ac ross the sample in a confocal geometry. Time resolution is achieved by chan ging the delay between the electrical pump and the optical probe, initial r esults show large local phase shifts in the ferroelectric response of close ly separated regions of a Ba0.5Sr0.5TiO3 thin film. This new experimental t echnique may help to understand the physical mechanisms of dielectric loss in these materials.