M. Zgonik

Photorefractive properties of iron-doped stoichiometric lithium niobate

The photorefractive properties of stoichiometric LiNbO(3) crystals with a small number of defect densities grown by the double-crucible Czochralski method are investigated and compared with the defect densities of commercially available congruent Fe-doped LiNbO(3) crystals. Two-wave-mixing experiments show that novel stoichiometric crystals exhibit larger photorefractive gain and considerably faster response times than congruent ones. The results indicate that the nonstoichiometry defect control of photorefractive crystals is of key importance for the improvement of their properties.

Ion implanted optical waveguides in nonlinear optical organic crystal

We report for the first time to our knowledge optical waveguiding in an organic crystalline waveguide produced by ion implantation. Using H+ ions a refractive index barrier suitable for waveguiding has been realized in the highly nonlinear optical organic crystal 4-N, N-dimethylamino-4-N-methyl-stilbazolium tosylate (DAST). The refractive index changes in the waveguiding region as a function of the distance from the surface have been measured. Maximal refractive index changes of up to -0.2 and -0.1 at wavelengths of 633nm and 810nm have been realized, respectively. The waveguide refractive index profiles as a function of the ion fluence have been determined. Planar waveguiding has been demonstrated by polishing sharp edges and using conventional end-fire coupling. The measured losses are approximately 7 dB/cm at 1.57mum.

Optical waveguides in the highly nonlinear optical organic crystal DAST by ion implantation and e-beam structuring

This study aims to fabricate optical planar waveguide structures by H+ ion implantation and direct electron beam patterning. Waveguide losses of ~20 dB are measured by light scattering detection. A reduction of the refractive index of the organic crystal is observed which is due to reduced polarizability of some molecules.

Optical waveguides in the highly nonlinear optical organic crystal DAST produced by ion implantation and fs ablation

Optical waveguiding in the highly nonlinear optical crystal DAST has been demonstrated. Planar waveguides have been realized by H+ ion implantation whilst fs ablation has been used to pattern channel waveguide structures.

Scanning Probe Microscopy of Ferroelectric Domains near Phase Transitions

In this chapter the results of scanning probe microscopic (SPM) investigations near ferroelectric (ferroic)—paraelectric phase transitions are presented. Submicroscopic investigations of domains near the transition temperature are of fundamental importance both for the basic understanding of the phase transitions itself but also for devices operating near the transition temperatures.