Chapter 12.1 - 3D microoptics via ultrafast laser writing: Miniaturization, integration, and multifunctionalities

Abstract

Trends of evolving technology usually are based on miniaturization and increasing complexity of devices or combining both of them. Three-dimensional (3D) laser structuring of materials employing ultrashort pulses is widely used in photopolymer rapid prototyping spanning microoptical elements, optical actuators, microfluidic chips, scaffolds for cell growth and tissue engineering, templates for plasmonic metamaterials, and photonic crystals (PhC). It is one of the most precise additive manufacturing technologies ever developed in both scientific and industrial fields. Despite already appearing as commercially available setup still some active engineering is being carried out, for instance, implementation of active autofocusing and machine vision for sample detection and positioning. In order to achieve resolution of structuring required for microoptical and PhC structures operational at visible spectral range, the feature dimensions should be controlled with ∼10nm spatial precision. Despite recent advances in techniques’ versatility, regarding specifically optical applications, the research inherits some gaps due to an initial pure engineering approach to 3D fabrication. For instance, the materials designed for 3D direct laser writing (DLW) are not fully (or barely at all) characterized and their optical performance and reliability have to be established. Thus, despite the DLW technique being mature and commercially available, some standard knowledge for its application in fabricating microoptical and photonic devices must be considerably improved, namely, the linear and nonlinear properties of the material itself, its modulation due to DLW structuring and postprocessing, taking into account various side effects and artifacts, e.g., an optical resistance. These investigation vectors are currently actively performed by many research groups.