Assembly of alignment-sensitive optical systems remains challenging because even small positional or angular errors can measurably affect system performance. In solid-state lasers, such errors can lead to changes in output power, beam quality, and stability. As a result, assembly of these systems remains largely manual, which increases production effort and cost, limits scalability, and often results in bulky designs constrained by large kinematic optic mounts. To address this challenge, this paper presents a feedback-guided robotic assembly workflow for compact, alignment-sensitive optical systems and validates it experimentally with a diode-pumped ruby laser. The workflow combines vision-guided pickup and passive placement with fluorescence-based axial positioning of the crystal, optical-feedback-based cavity alignment, stepwise optimization of the laser output, and permanent fixation via UV-curable adhesive. The process was implemented on a commercial precision optics assembly platform and executed without manual adjustment. As a representative validation case, the assembled ruby laser produced diffraction-limited output at 694.3 nm with an output power of 30 mW. The results show that passive placement, in situ optical feedback, optimization, and bonding can be integrated into a repeatable robotic process for laser assembly. The demonstrated workflow provides a practical route toward automated assembly of optical systems whose performance depends critically on precise alignment and on preserving that alignment during and after bonding.

A method of determining the thermal properties of optical thin-film filter materials from spectrophotometric measurements is proposed. Its feasibility is shown by extracting the material properties from simulated transmission spectra imprinted with real-world measurement errors. A Monte Carlo-based algorithm was implemented to optimize thin-film filter designs for thermal stability. This algorithm is used to explore the optimization possibilities of exemplary designs for differently behaving material combinations. It is demonstrated that designs can be optimized for use under different temperatures, where also the overall wavelength shift of a filter is modifiable.

The trend of consistent increases in laser power is often limited by the laser-induced damage threshold (LIDT) of the optic. Existing models have shown a link between the nonlinearv ionization rate at high intensities and LIDT. These models are extended to account for the presence of intermediate states and compared to laser calorimetric absorption (LCA) measurements of samples prepared with varying densities of intermediate states. Hafnia is well established for use in high LIDT optics due to its large band gap and high refractive index; however, a number of defect states can be induced by oxygen sub- or super-stoichiometry. The extended model shows good correlation to measurements of samples prepared with different densities of intermediate states.

A combined laser-induced damage threshold (LIDT) measurement routine is presented specifically for optics, which are subject of further optimization to nanosecond fusion laser optics. By extending a raster scan method with an R(S)-on-1 routine that has a last intact spot damage criterion, not only the current LIDT limited by the most critical defect is measured but also up to the intrinsic LIDT of the coating. This demonstrates how existing routines can be combined to distinguish between a defect-driven and an intrinsic damage threshold. During coating optimization studies, this allows to correlate specific coating process parameters directly to their influence on both the defect-driven and the intrinsic LIDT of the coating. A high-quality in situ microscopic imaging during the measurement routine is essential for the precise LIDT evaluation, and combined with high-precision ex situ measurement techniques, it allows an even more detailed investigation of participating damage mechanisms. An exemplary cross-sectional microstructure damage analysis showed that observed changes in color can be linked to a local delamination of the coatings top layer and a change in reflectivity.

An upscaling concept of the ion beam sputtering process for large area optics is presented with a novel approach including a movable ion and deposition material source. First deposited single layers show promising results.

We investigated the laser-induced damage threshold (LIDT) of seven metallic (Ag, Al, Au, Cr, Ta, Ti, W) and two semiconductor (Si, Ge) coatings on glass substrates as a function of the laser pulse duration using 1-on-1 and S(1000)-on-1 testing. Experiments spanning pulse durations from 10 femtoseconds to 10 seconds revealed two distinct LIDT scaling laws for pulsed and continuous-wave (CW) regimes. Numerical simulations of laser radiation coupling and heat diffusion in gold coating explained the observed scaling. They predicted the transition between pulsed and CW regimes, which depends on film thickness and material properties. For short pulses, LIDT is dominated by the metallic film, while for long pulses, heat dissipation into the substrate becomes critical. These findings enhance the understanding of LIDT scaling and the thermal dynamics of metallic coatings.

Optical fiber communication networks, lasers, and sensing technologies have advanced significantly worldwide. Beyond traditional glass fibers, polymer optical fibers (POFs) are gaining attention for short-distance communication and healthcare applications. These fibers offer advantages such as lightweight construction and high durability but face challenges including crystallization and contamination during the drawing process. Advanced techniques are necessary to characterize POFs at the nanoscale. This study employs small-angle X-ray scattering (SAXS) to analyze fiber structure, anisotropy, and crystallinity, providing valuable insights into their material properties. Our findings introduce a novel approach to POF characterization, with potential integration into drawing towers for real-time quality control and applications in studying laser-induced damage.

We report on an integrable electro-optic modulator (EOM), exploiting the advantages of substrate-free thin film technology to achieve a small device footprint of less than 30 mu m along the beam propagation direction. By integrating an electrooptically active layer into a resonant Fabry-Perot (FP) structure with dielectric thin film mirrors, an EOM, which modulates the transmitted amplitude, is manufactured and characterized. We show results on electro-optically active polymers as the FP cavity material, which have revealed an electro-optic coefficient in the three-digit pm/V range at a wavelength of 980 nm. Furthermore, we analyze the applicability of piezoelectric zinc oxide (ZnO) as the active layer material, which exhibits high transmission in the visible wavelength region. Fabrication of ZnO using magnetron sputtering under oblique angle deposition conditions has the potential to produce porous, inclined, crystalline thin films with an enhanced piezoelectric coefficient d(33), which is otherwise only found in bulk ceramics like lead zirconate titanate. The use of such nanostructured ZnO thin films with an improved electro-mechanical coupling as active cavity layer fosters improved modulation while consuming less energy.

A method of determining the thermal properties of thin-film filter materials from spectrophotometric measurements is proposed. Its feasibility is shown by extracting the material properties from simulated transmission spectra imprinted with real world measurement errors.

Manufacturing coatings with precise spectral features and the required spatial homogeneity is challenging for extreme large substrates of about 2 m in diameter. Here, a digital twin model is presented that supports the new process development significantly to coat substrates of this size with high precision, suitable for interference coatings. Recent demands for these large optics originate from astronomy with large telescopes such as the Extreme Large Telescope (ELT). Since the established manufacturing processes do not scale efficiently with the substrate size, more effort is necessary to produce coatings with a thickness precision of about 1 % or better for single layers, which is often specified for high-quality interference coatings. Therefore, a novel concept for an ion beam sputtering plant with a moving ion source/target carrier is developed. The digital twin model combines several simulation methods in the virtual coater framework. Within this model, a method for determining the required movement track of the carrier is developed, which can then be easily transferred to experimental tests. Further atomistic simulations by molecular dynamics facilitate estimations of structural differences in the lateral dimension that mainly originate from parasitic sputtering. Also the findings are compared to preliminary experimental results.

Using a new coating procedure in the IBS process, hybrid quantizing nanolaminates based on Ge and TiO 2 were prepared. A refractive index of over 3.4 was measured for 1550 nm and the band gap was shifted to a wavelength of 1377 nm.

The deposition process by ion beam sputtering is scaled to a huge substrate size. Homogeneous coatings are optimized by adjusting the moveable target positions. A digital twin model combines gas flow and atomistic growth simulations.

During deposition of hafnia thin films, defects such as oxygen vacancies or super-stoichiometry can lead to the formation of intermediate states between the valance and conduction bands. These were investigated for nonlinear absorption.

Quantizing nanolaminates are an optical metamaterial that has been a prominent research topic in the community of thin film technology for several years. In previous works, the calculations for the theoretical description of the electronic properties were limited to a single quantum well with finite barriers, whereby interactions of several quantum wells or deviations of the potential form could not be taken into account. This paper presents a new theoretical foundation based on the matrix solution of the discretized Schrödinger equation, which allows the calculation of structures with up to 500 quantum wells and arbitrary potential shapes. Based on this model, the influence of the barrier thickness and the number of potential wells on the absorption edge of this metamaterial is analyzed. Furthermore, the influence of layer thickness errors is discussed and compared to experimental data. In addition, a study on the wavelength-dependent absorption as a function of the interfaces is presented. Lastly, future applications and further developments in coating technology for the efficient production of high-quality quantizing nanolaminate coatings are discussed.