Investigation of the spatial polarization distribution of pyroelectric thin films using the laser intensity modulation method

摘要

In this paper the laser intensity modulation method (LIMM), e.g. the determination of the spatial polarization profile from the measured pyroelectric current spectrum caused by the interaction of laser induced thermal waves and the unknown polarization distribution, is applied for the investigation of pyroelectric thin films on a massive silicon substrate or thermally isolating membrane, respectively. The unknown spatial polarization distribution is not directly accessible from the measured pyroelectric current spectrum. The reconstruction of the spatial polarization distribution needs to solve a Fredholm's integral equation of the first kind which is a so-called "ill-posed" problem. To overcome this problem the Tikhonov regularization method is used in order to get a stable solution of the reconstructed polarization profile.