The rapid expansion of femtosecond (fs) laser technology brought previously unavailable capabilities to laser material processing. One of the areas which benefited the most due to these advances was the 3D processing of transparent dielectrics, namely glasses and crystals. This review is dedicated to overviewing the significant advances in the field. First, the underlying physical mechanism of material interaction with ultrashort pulses is discussed, highlighting how it can be exploited for volumetric, high-precision 3D processing. Next, three distinct transparent material modification types are introduced, fundamental differences between them are explained, possible applications are highlighted. It is shown that, due to the flexibility of fs pulse fabrication, an array of structures can be produced, starting with nanophotonic elements like integrated waveguides and photonic crystals, ending with a cm-scale microfluidic system with micro-precision integrated elements. Possible limitations to each processing regime as well as how these could be overcome are discussed. Further directions for the field development are highlighted, taking into account how it could synergize with other fs-laser-based manufacturing techniques.

Femtosecond laser based 3D nanolithography is a powerful tool for fabricating various functional micro- and nano-objects. In this work we present several advances needed to push it from the laboratory level use to the industrial production lines. First, linear stage and galvo-scanners synchronization is employed to produce stitch-free mm-sized structures. Furthermore, it is shown that by varying objective numerical apertures (NA) from 1.4 NA to 0.45 NA, voxel size can be tuned in the range from sub μm to tens of mm, resulting in structuring rates between 1809 μm³/s and 313312 μm³/s at 1 cm/s translation velocity achieved via simultaneous movement of linear stages and scanners. Discovered voxel/throughput scaling peculiarities show good agreement to ones acquired with numerical modeling. Furthermore, support-free 3D printing of complex structures is demonstrated. It is achieved by choosing pre-polymer that is in hard gel form during laser writing and acts as a dissolvable support during manufacturing. All of this is combined to fabricate micromechanical structures. First, 1:40 aspect ratio cantilever and 1.5 mm diameter single-helix spring capable of sustaining extreme deformations for prolonged movement times (up to 10000 deformation cycles) are shown. Then, free-movable highly articulated intertwined micromechanical spider and squids (overall size up to 10 mm) are printed and their movement is tested. The presented results are discussed in the broader sense, touching on the stitching/throughput dilemma and comparing it to the standard microstereolithography. It is shown where multiphoton polymerization can outpace standard stereolithography in terms of throughput while still maintaining superior resolution and higher degree of freedom in terms of printable geometries.

The ever-growing trend of device multifunctionality and miniaturization puts enormous burden on existing manufacturing technologies. The requirements for precision, throughput, and cost become increasingly harder to achieve with minimal room for compromises. Femtosecond lasers, which saw immense development throughout the last few decades, have been proven time and time again to be a superb tool capable of standing up to the challenges posed by modern science and the industry for ultrahigh-precision material processing. Thus, this paper is dedicated to provide an outlook on how femtosecond pulses are revolutionizing modern manufacturing. We will show how they are exploited for various kinds of material processing, including subtractive (ablation, cutting, and etching), additive (lithography and laser-induced forward transfer), or hybrid subtractive-additive cases. The advantages of using femtosecond lasers in such applications, with main focus on how they enable the most precise kinds of material processing, will be highlighted. Future prospects concerning emerging industrial applications and the future of the technology itself will be discussed.

Direct laser writing based on non-linear three-dimensional nanolithography (also known as 3D laser lithography, 3DLL) is a powerful technology to manufacture polymeric micro-optical components. However, practical applications of these elements are limited due to the lack of knowledge about their optical resilience and durability. In this Letter, we employ 3DLL for the fabrication of bulk (i.e., fully filled) and woodpile structures out of different photopolymers. We then characterize them using the S-on-1 laser-induced damage threshold (LIDT) measurements. In this way, quantitative data of LIDT values can be collected. Furthermore, this method permits to gather damage morphologies. The results presented demonstrate that LIDT values depend on the material and the geometry of the structure. Bulk non-photosensitized hybrid organic/inorganic photopolymer SZ2080 structures are found to be the most resilient with a damage threshold being 169 ± 15 m J / c m 2 .

Multiphoton 3D lithography is becoming a tool of choice in a wide variety of fields. Regenerative medicine is one of them. Its true 3D structuring capabilities beyond diffraction can be exploited to produce structures with diverse functionality. Furthermore, these objects can be produced from unique materials allowing expanded performance. Here, we review current trends in this research area. We pay particular attention to the interplay between the technology and materials used. Thus, we extensively discuss undergoing light-matter interactions and peculiarities of setups needed to induce it. Then, we continue with the most popular resins, photoinitiators, and general material functionalization, with emphasis on their potential usage in regenerative medicine. Furthermore, we provide extensive discussion of current advances in the field as well as prospects showing how the correct choice of the polymer can play a vital role in the structure’s functionality. Overall, this review highlights the interplay between the structure’s architecture and material choice when trying to achieve the maximum result in the field of regenerative medicine.

Optical aberrations are a type of optical defect of imaging systems that hinder femtosecond direct laser write machining by changing voxel size and aspect ratio in different sample depths. We present an approach of compensating such aberrations using a liquid crystal spatial light modulator (SLM). Two methods for correcting are explored. They are based on backward ray tracing and Zernike polynomials. Experiments with a long focal distance lens (F = 25 and 50 mm) and microscope objective (100x, 0.9 NA) have been conducted. Specifically, aberration-free structuring with voxels of a constant aspect ratio of 1-1.5 is carried out throughout a 1 mm thick sample. Results show potential in simplifying direct laser writing and enabling new architectures made possible by near-spherical voxels.