Optical components can be tailored for specific applications by artificially structuring the materials they are made up of. We are working on stratified linear and nonlinear media and try to incorporate materials and components from neighboring fields in lasers to provide them with new or improved functionality. Some examples on materials and technologies that we presently work on are; periodically poled ferroelectrics, volume Bragg gratings, functional fiber components, laser written waveguides, silicon micro-benches, tunable silicone gratings, fluorescent nanodots, and dye doped fluids. Combining linear and nonlinear photonic crystal properties together with micro-mechanical and microfluidic functionality will lead to new capabilities in future photonic and biophotonic devices.
Domain-engineered ferroelectrics
Our group has been involved in domain engineering of ferroelectrics for more than 20 years. At present we develop one and two dimensional structures in stoichiometric LiNbO3 and LiTaO3, and KTiOPO4 isomorphs. Domain gratings with micrometer size periods are used as nonlinear wavelength converters in various lasers and parametric devices, as described below, while the two-dimensional structures are used as nonlinear photonic crystals.The work on nanodomain engineering is more fundamental where we try to understand the physical and chemical limitations in formation of small domains and domain dynamics.
1D PPKTP with a 720 nm period.
Domain engineering is closely coupled to the material properties and we have lately compared more defect free stoichiometric crystals with congruent ones. To date we have reached unprecedented domain aspect ratios in the KTP isomophs and this been used for development of unique devices like the mirrorless optical parametric oscillator. Furthermore, domain to domain interplay and self-formation processes are under investigation. On the analytic side we are also developing improved, non-destructive methods for domain characterization.
