Periodic Structuring of Material Parameters in Ferroelectric Crystals with Ion Exposure

• Antragsteller: Professor Dr. Karl Maier
• Fachliche Zuordnung: Optik, Quantenoptik und Physik der Atome, Moleküle und Plasmen
• Förderung: Förderung von 2004 bis 2011
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 5471245

Within this project, waveguides will be fabricated by a novel method: lithium niobate crystals (LiNb03) and lithium tantalate crystals (LiTaO3) will be exposed to accelerated ions (e.g.,2D, 3He, a particles). This exposure generates refractive index changes that are large enough to create light-guiding structures. The method should be applied especially to crystals studied in Project C4. However, techniques to fabricate low-loss waveguides that do not impact the other crystal properties are in general the key for several efficient devices with small form factors. Within the project a detailed physical understanding of the underlying microscopic mechanisms will be revealed by X-ray absorption spectroscopy and positron microprobe measurements. These techniques will allow for a study of the generated local defects as well as the general defect chemistry in Li-enriched LiNb03:Mn and LiTaO3:Mn crystals as they will be used in Project C4. Key questions are: Which defects are induced by the radiation? What are the properties, e.g. impact an ferroelectricity and photorefractivity, diffusion behavior, life-time, and absorption, of these defects? Frequency doubling and optical parametric oscillation by using quasi-phase-matching in periodically-poled LiNbO3 or LiTaO3 are two examples of promising applications. The goal of, e.g., Project C4 is to realize monolithic optical parametric oscillators that contain Bragg gratings as mirrors. Large frequency conversion efficiencies require high light intensities and long interaction lengths. Both can be provided by utilizing waveguiding structures in the crystals. Furthermore, high metal contents will increase the electric conductivity and hence reduce the so-called "optical damage" (unwanted space-charge-field-induced electro-optic refractive-index changes). Generation of refractive-index changes by particle exposure as well as a study of the defect chemistry of LiNbO3 and LiTaO3 crystals by the present project bear fascinating physics and can become key enablers for these applications.

• DFG-Verfahren: Forschungsgruppen
• Teilprojekt zu: FOR 557: Light Confinement and Control with Structured Dielectrics and Metals
• Beteiligte Person: Dr. Konrad Peithmann