BPM simulation of SNOM measurements of waveguide arrays induced by periodically poled BNN crystals

摘要

The simulation of light propagation using standard beam propagation techniques, in periodically inverted domains in Ba_2NaNb_5O_(12) crystals is presented. The poled domains pattern gives rise to periodic modulation of the refractive index in the crystal, which can be observed with diffraction experiments and simulated by one-dimensional beam propagation methods. The micro-domains are characterized by Scanning Near Field Microscopy, using both transmission and collection modes. In particular, under the collection mode, micro-pictures have been obtained with unexpected high optical contrast between positive and negative domains of up to 80%. Using a beam simulation method, the results are explained considering that the ferroelectric domains operate as a periodic array of planar waveguides.