Adaptive spatio-temporal techniques for smart ultrafast laser processing of optical glasses

Ultrafast lasers emerged as efficient tools to process transparent materials on minimal scales. Localized refractive index changes can serve as building blocks for embedded optical functions. The requirements of a desired photonic response involve precise adjustments of the refractive index which usually depends on the material relaxation paths. Advanced strategies are then required to improve the irradiation results. Recently, new beam manipulation concepts were developed which allow a modulation of the energy feedthrough according to the material transient reactions, enabling thus a synergetic interaction between light and matter and, therefore, optimal results. Considering the potential of optical functionalization, we discuss the possibility of controlling laser-induced modifications of transparent materials employing automated temporal pulse shaping. Examples of adaptive design of refractive index changes in glasses will be shown, accompanied by concepts of efficient processing approaches. This involves an engineering aspect related to simultaneous processing of structural modifications in 3D arrangements where a feasible solution is represented by dynamic spatial beam shaping techniques. The approach has a dual aspect and includes corrections for beam propagation errors and spatial intensity distributions in desired forms for parallel processing. Adding the possibility of laser-induced birefringence, photowritten structures can be arranged in patterns generating complex propagation and polarization effects.