Nanoscale opto-electronic devices have the potential for combining the high bandwidth of light with the integration density of modern-day microelectronics. Its applications demand a material that brings together high conductivity, easy processability and superior optical properties. Single-crystalline gold platelets show decreased optical damping compared to evaporated films and allow electronic access through nanometer sized connectors. Here we demonstrate the combination of focused ion beam structuring of single-crystalline gold platelets and subsequent dielectrophoresis that allows us to realize complex antenna designs with tailored emission profiles as well as the integration of electrically-driven nanometer sized light sources into optical nanocircuits.

Nanogap separated coplanar electrodes that can be manufactured with high throughput, and indeed on thin flexible substrates, can be used to realise nanodevices with lower power consumption, faster speed and higher level of integration. Adhesion lithography is a nanopatterning technique, which enables the low-cost facile fabrication of coplanar asymmetric metal electrodes separated by a sub-15 nm gap on arbitrary type and size substrates. It will be shown that these nanogap electrodes, when combined with suitable light-emitting and light-absorbing materials, while employing solution processing protocols, give rise to nanoscale light-emitting and photodetecting devices with high response speed and attractive performance characteristics.

Large area fabrication of high index chalcogenide metasurfaces on soft substrates are proposed first time by thermal dewetting technique. Such metasurfaces are shown to have application in monolayer of protein detection or strong second harminic enhancement due to the observed Fano resonance of FWHM of 4 nm in the vbisible regime.

Membrane projection lithography (MPL) is a fabrication approach which leverages mature silicon processing equipment with a novel microelectromechanical system (MEMS)-based process flow to create three-dimensional metamaterials with size scales which make them operational at optical frequencies. We demonstrate several enhancements to the MPL fabrication approach for creating 3D optical metamaterial structures for use in the infrared wavelength range, making the study of 3D metamaterials accessible to institutions with low-tech semiconductor fabrication facilities.

We present a surface-agnostic strategy for face-selective immobilization of DNA-origami onto solid substrates using the fluorous effect. The incorporation of fluorous-modified ODNs onto one face of a 2D nanostructure is used to produce ‘Janus face’ RF-origami. The ponytails significantly reduce the probability of surface interaction, resulting in the origami being immobilized with their fluorous-face orientated ‘upwards’. Furthermore, we show that the fluorous tails have dual functionality: in addition to directing facial-selectivity, they can also be used as a molecular recognition modality to direct the assembly of gold nanoparticles.

Here we report a novel fabrication approach to integrate 2D nanostructures on the facet of optical fibers by electron beam lithography. To demonstrate this approach, we have implemented two types of gold structures on the on the end face of 50 cm long standard single mode fibers (SMF-28): the one is gold nanotrimers lattice and the other is nanodots array. This fabrication method is not limited to the nanostructure geometry reported here and can also be applied to dielectric nanostructures, thus opening up the field of fiber optics for planar nanostructures within numerous application fields including bioanalytics, telecommunications, optical trapping and beam shaping.

Here we present the fabrication a miniaturized polarization retarder element with a Direct Laser Writing method. A miniaturized Fresnel Rhomb, acting as a quarter-waveplate with a very broad operating bandwidth (exceeding 300 nm), has been 3D printed on a polarization maintaining optical fiber to obtain a miniaturized on-fiber broadband source of pure circularly polarized light. Our structure could find application on a remote ultra compact probe in circular dichroism and Raman Optical Activity spectroscopies but could also be used as a phase retarder for other integrated applications, where control of the polarization on small scales is needed.

This general overview talk will focus on enhanced light-latter interactions on nanostructured surfaces for real life applications. Light-matter interactions can be controlled by manipulating the electric and magnetic responses of a material. Specifically, uncooled detection of mid-IR photons, skin-like displays, structural color based metallic paints, neural sensing and infrared concealing/camouflage will be highlighted. The newly developed direct laser writing and various printing techniques enable large area patterning of such nanostructured surfaces for low cost manufacturing.

Applying a technique inspired by super-resolution imaging, it is possible to achieve sub-diffraction limited line widths in far-field photolithography. Using interference lithography as a demonstration platform, and exposing with a wavelength of 364 nm, we demonstrate high fidelity 50 nm features. Furthermore, these features are written over a large area with high uniformity and repeatability. As only off-the-shelf photoresists are used, this method is compatible with existing cleanrooms and adaptable to some existing lithography tool sets. In this talk we detail the engineering analysis of both the technique and of the interference lithography tool. Funding provided by Sandia National Laboratories. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA000352.

Optimum photonic structuring of the front and/or back surfaces is one of the crucial process steps in attaining high photo-conversion efficiency in solar cells. In this study, a novel single-step, fast and facile laser-induced nano-patterning technique of Si surfaces is developed and employed in the standard production cycle of Si solar cells. Computational (RCWA) and experimental results agree on efficient wideband light absorption, giving rise to a >21% increase in Si solar cell photo-conversion efficiency. Attractiveness of the proposed and applied technique lies in its single-step nature rendering the technique fast, reproducible, cost-effective and free from hazardous process waste.

Micro-lens array manufacturing by using an inkjet printing technology allows for the manufacturing of large area arrays on lithographically structured substrates that contain oleophobic and oleophilic surface patterns. An inkjet printing process deposits the high performance, hybrid polymer ORMOCER on the oleophilic pattern. The material forms by means of surface tension and wetting boundaries a lens shape, while the inkjet printing process itself enables for a highly parallel manufacturing of many lenses at the same time. A typical geometrical deviation <1% of the radius of curvature for lenses with diameters of <1 mm, ROC’s of ca. <2 mm and sag heights of <100 microns was achieved. Also a specific lithography processing regime was derived that combines wetting patterns with optical apertures to enable advanced illumination setups like multi-aperture projection.

Here, the nanoscale additive manufacturing technique direct laser writing is explored as a method to print cantilevered probes for atomic force microscopy. Not only are these 3D printed probes found to function effectively for imaging, but they also confer several advantages, most notably the ability to image with a bandwidth approximately ten times larger than analogous silicon probes. In addition, the arbitrary structural control afforded by 3D printing enables programming the modal structure of the probe, allowing one to resonantly amplify non-linear tip-sample interactions. Collectively, these results show that 3D printed probes open the door to new imaging techniques.

We present our approach to incorporate nanodiamonds into direct-laser-written three-dimensional polymer waveguides. The nanodiamonds house ensembles of 10^3 nitrogen vacancy centers, acting as sensitive probes for, e.g., magnetic fields that can be read-out optically. Guided by the waveguide structure, detection of the optical signal from the nanodiamond does not require direct optical access. We show optically detected magnetic resonance spectra together with Rabi oscillations on an effective two-level system in waveguide-embedded nanodiamonds. We compare their performance with free-space emission and complement our experimental studies by numerical simulations. This approach opens the way for on-chip three-dimensional structures for optically integrated spin-based sensing.

We report on the imaging of latent 3D features exposed in photoresist during Direct Laser Write micro-/nano-fabrication. The imaging method is based on monitoring of photoluminescence emitted by photonitiator in the photoresist, and exploits photoluminescence quenching and its dependence on the dose of the previous optical exposure. By spatially scanning focus of a low-intensity laser beam over the previously recorded latent features, spatial PL intensity maps reveal negative image of the latent pattern, and allows determination of feature size and shape prior to development. The imaging can be carried {\em in situ}, immediately after the fabrication, and does not require extensive modification to the existing equipment.

Fabrication of 3D dielectric photonic crystals in the visible and in the infrared range typically requires sub-micron structural features and high-refractive index materials. We developed a template-free additive manufacturing (AM) process based on direct laser writing (DLW) that can create complex 3D architectures out of titania (TiO2) with ~100 nm resolution.

While additive manufacturing is well-established in a variety of application scenarios, 3D printing for optics manufacturing is still regarded as a “holy grail” for optical designers. We demonstrate the application of hybrid polymers (ORMOCER®s) as photocurable resins for 3D printing of optics by stereolithography, inkjet-printing and two-photon polymerization (2PP). In particular, we focus on the introduction of CdSe quantum dots (QDs) into an ORMOCER® matrix material. This nanocomposite is processed by DMD-based printing approaches. Additionally we present the generation of 2PP microstructures (microlenses and diffractive optical elements) on 3D printed (curved) surfaces. 2PP structures made from pure hybrid polymers and from nanocomposites will be discussed in our presentation.

Structural color phenomena exhibited by several organisms result from interference and diffraction of light incident upon multilayer nanostructures. These biomimetic nanostructured surfaces produce structural coloration for desired angle-variant distributions of reflectance spectra. Previous work has demonstrated the utility of inverse design methodologies in the computational formulation of nanostructures tailored for specific spectral responses, generally tailored around a single spectral band. In this work, we depict a design methodology based around computational inverse design for the formulation of nanostructures exhibiting composite structural coloration in a variety of disjoint spectral bands. We furthermore depict example design constraints and study convergence with respect to the design trade space. Such complex biological systems require advanced fabrication techniques, and replication of nanoscale features of this complexity has been difficult. Our designs are constrained for realizable fabrication using direct laser writing techniques such as two-photon polymerization. This process provides a toolkit with which to examine and build other bio-inspired, tunable, and responsive photonic systems and expand the range of achievable structural colors. Sample experimental results of nanostructures fabricated via two-photon polymerization are presented.

Non-uniform surface relief gratings were laser-inscribed on azobenzene molecular glass thin films using a modified Lloyd’s mirror interferometer. The azobenzene films were exposed to an adjustable interference pattern obtained from the recombination of collimated and spherically divergent laser beams. The localized pitch, grating vector orientation and depth of several non-uniform gratings, with central pitches ranging from 500 nm to 2000 nm, were measured and characterized experimentally. These gratings exhibited a chirping or pitch variation along the imposed X-axis as well as an angular change in the grating vector orientation along the imposed Y-axis.

Multispectral filter arrays (MSFAs) are thin-film optical filter mosaics integrated atop image sensor pixels, that provide spatially resolved color information. MSFAs are typically fabricated using a dye/pigment-based approach or a multi-layer dielectric stack, whereby for N-spectral bands, N-lithographic steps are required. Here, we experimentally demonstrate a novel framework for producing high efficiency (~80%), narrow linewidth (~50nm), highly customizable MSFAs using a single lithographic step. Using grayscale lithography to define insulator thicknesses of metal-insulator-metal cavities, we fabricated MSFAs operating across the UV—visible—near-infrared. We then performed multispectral imaging using our custom MSFAs atop commercial CMOS image sensors.

In this work we present a comparative study of two processes for the fabrication of an array of microchannels for microfluidics applications, based on integratAedB-cSirTcuRitAteCchTnology process steps, such as lithography and dry etching. Two different methods were investigated in order to study the resulting microstructures: wet and dry deep etching of silicon substrate. The typical etching depth necessary to the target application is 50 μm.

We propose fabricating of geometric phase micro-optical elements (GPµOE) via direct laser write (DLW) 3D nanolithography. It is an efficient way to produce highly integrated micro-devices, since they can be stacked with other polymer optical components, mounted on glass/crystal substrates, dielectric thin film membranes, fiber-tips or even left free floating. An improvement of the DLW fabrication procedure via fine polarization control of the writing beam and optimization of hybrid prepolymer SZ2080 (low shrinkage, 0.4-2.5 µm optical transparency) composition is demonstrated. The absence of photo-initiators is beneficiary due to optical transparency of printed structures, while the addition of polymerization quencher (2­(dimethylamine)ethyl methacrylate (20%wt.)) leads to further increase in structuring resolution.

In view of the increasing demands on precision optics, microelectronics and precision mechanics nanoscale structuring processes are of great interest. It is becoming more and more important to apply a large number of structures that are as small as possible to ever larger areas with high reliability and to increase the number of structures per area element (packing density). The straightness and uniformity of these structures, as well as the positioning accuracy during the fabrication of such narrow lines and points are at the center of the increase of the packing density. A further decisive role is played by the development of suitable sensors and tools for the production and measurement of these structures. The development and the combination of a new laser based probe for the measurement and a direct laser writing (DLW) tool for the creation of sub-micro structures forms the core of this topic. The new sensor is based on a confocal measuring principle. A fiber coupling is used to avoid thermal influences. At the same time, the fiber end itself serves as a confocal pinhole. For the process tool, comprehensive investigations of laser and resist parameters are necessary. The first results are shown. These two parts are investigated separately and combined at the end of the work. In order to achieve the necessary positioning accuracy, the tool is integrated into the Nanopositioning and Measurement Machine (NPMM).

GaN microLEDs can be used as powerful integrated light sources in microsystems for various applications. Additional introduction of high-precision microoptical elements for narrowing the angular intensity characteristics of microLEDs can reduce the emission losses and prevent the spatial resolution downgrade. However, direct integration of the microlenses onto microLEDs cannot be done with conventional fabrication methods. Thus, a device integration technique based on polydimethylsiloxane structure transfer is proposed to guarantee precise positioning of polymer microlenses on top of microLEDs. Owing to their superior properties, the realized SU-8 microlenses can be suitably combined with GaN microLEDs as versatile optical devices.

We developed a cost-effective fabrication technique for a large area metal enhanced fluorescence (MEF) substrate composed of the metallic nanolens array with a narrow gap. The metallic nanolens array MEF structure was fabricated by UV-nanoimprinting and physical vapor deposition process of SiO2 and Ag layers. To optimize the shape of nanolens array, the inter-lens spacing was controlled by changing the thickness of deposited SiO2 layer. The maximum MEF of ~ 128 was obtained by the nanolens array with a SiO2 layer thickness of 150 nm, and Ag layer thickness of 100 nm, where the inter-lens spacing was ~40 nm.

An antireflective glass nano structure by unfilled glass imprinting process on soda-lime glass using vitreous carbon (VC) stamp has been proposed. For the realization, a nano-post pattern VC mold with a pitch of 320nm, a diameter of 110nm and height of ~ 230nm was fabricated by carbonization of replicated furan precursor from nanodot pattern Si master (400nm pitch, 200nm diameter, and 500nm height). Various dome shape surface profile was obtained in each glass imprinting condition and the optimized imprinting temperature of 690°C and pressure of 2MPa, the light transmittance of 2% increased compare to bare glass in whole visible wavelength.

We present a method to write a tapered waveguide using fixed-beam-moving-stage (FBMS) in an electron-beam lithography system. FBMS allows wiring of large patterns without stitch-error, however, restricts only few primary shapes. For pattering tapers, a combination of FMBS with area mode is used that typically results in alignment errors. The proposed method offers smooth and alignment-error-free tapering of submicron featured Silicon waveguide. We experimentally demonstrate a fully FBMS patterned photonic circuit with power splitter, wire-to-slot coupler, slot waveguide and a slotted ring resonator. The device response with insertion loss -1.35 dB is measured using a tunable laser source around 1550 nm wavelength.

We study the chromatic behaviour of the photonic nanojet by examining micro ball-lenses of various sizes. Using interferometric techniques, we measure the spot-size of the nanojet with high precision and, combining it with the focal length measurement, we calculate the numerical aperture of the lens. The change of those parameters with respect to the wavelength is used to determine the transition among the scattering, refractive and diffractive optical regimes. The beam-spot size scales proportionally to the wavelength, but the focal length shift is a few microns, indicating achromatic behaviour.

In this presentation, we propose a novel stereolithographic three-dimensional (3D) printing process that uses Lissajous trajectories, which has been frequently used in high-speed imaging system. We describe fundamental mathematical background for Lissajous scanning in 3D printing process, and characterize printing conditions depending on the scanning mirror speed and laser modulation capability. We build a 3D stereolithographic system, and demonstrate its high-speed 3D printing capability by evaluating its performance in the view of 3D fabrication resolution and speed.

Almost two decades have passed since the realization of complete 3D photonic crystals at optical wavelengths. During these years, the manipulation of photons by photonic crystals has progressed tremendously. For example, the concept of confining photons to a very small modal volume has been established and nanocavity Q-factors have exceeded ten million, enabling platforms for strong light-matter interaction and quantum information processing. Photonic crystals allow even a broad-area manipulation of photons, by which semiconductor lasers with a very bright, narrow-divergence beam and various functionalities including 2D beam steering have been realized. Such lasers are promising for applications in light-detection and ranging (LiDAR) and direct material processing, which are important for the forthcoming Society 5.0. Photonic crystals also enable thermal emission control, by which the issues of conventional thermal emission devices such as their extremely broad emission spectra and slow response speed have been fixed, and a renovation of thermal emission devices has been achieved. In this plenary talk, we will review such progress of photonic crystals including their social applications.

In the first part of this presentation, we will discuss recently emerging applications of the state-of-art deep learning methods on optical microscopy and microscopic image reconstruction, which enable image enhancement and new transformations among different modalities of microscopic imaging, driven entirely by image data. In this second part, we introduce a physical mechanism to perform machine learning by demonstrating a Diffractive Deep Neural Network architecture that can all-optically implement various functions following the deep learning-based design of passive layers that work collectively. We created 3D-printed diffractive networks that implement classification of images of handwritten digits and fashion products as well as the function of an imaging lens at terahertz spectrum. This passive diffractive network can perform, at the speed of light, various complex functions that computer-based neural networks can implement, and will find applications in all-optical image analysis, feature detection and object classification, also enabling new camera designs and optical components that perform unique tasks using diffractive neural networks.

We use point-spread-function (PSF) engineering, namely, modifying the shape that a point source creates in the image plane of a microscope, to encode the depth and color of a sub-diffraction fluorescent emitter. This is achieved by shaping the wavefront of the light emitted from the sample, using a phase mask in the pupil (Fourier) plane of the microscope. In this talk we present experimental results of tracking and imaging synthetic fluorescent sources and bio-molecules, and discuss the unique fabrication challenges associated with these applications.

In medical imaging, physical models known as phantoms are used to evaluate and track imaging system performance quantitatively with well-controlled physical properties that often mimic biological structures. To support progress of adaptive optics imaging in ophthalmology, we used two-photon polymerization to create the first-ever phantom with controlled micron-scale features, mimicking cone photoreceptor cells. We examined the phantom in different ophthalmic imaging modes and across laboratories. We used the phantom to determine imaging performance metrics and to investigate speckle and waveguiding properties unique to the retina.

Direct laser writing (DLW) has evolved to a versatile research tool. Besides, DLW enters engineering applications due to progress in accuracy, usability and especially fabrication speed. Here, we demonstrate the impact of three-dimensionally structured surfaces for engineering applications. First, precisely structured surfaces allow for a holistic ISO-conform calibration of optical measurement devices. Second, we study dynamic interactions of particles with component surfaces, e.g. the coefficient of restitution. The fabrication of specifically designed stamp-structures allows for labeling of particles (diameter <400 µm) to study their rotation behavior. For all these experiments, knowledge of the material’s parameters is required. Therefore, a successive combination of micro milling and DLW paves the way for a direct determination of the mechanical properties of direct laser written structures by in-situ quasi-static tensile tests.

Micro- and nanofabrication has grown in the last decades due to lithographic techniques and direct laser writing. The structure sizes could be reduced down to certain nanometers and two-photon polymerization and UV-direct writing have become common tools besides the conventional UV-lithography. A main problem in direct laser writing manufacturing is the limited positioning range, in which the laser focus can be moved through the photosensitive material. A combination of a nanomeasuring and nanopositioning machine with a femtosecond laser enables direct laser writing in a large volume and provides a resolution in the sub-nanometer range and additionally metrological traceability.

Nanophotonics is based on the ability to construct optical structures with specifically designed spatial distributions of the refractive index (RI). This is accomplished through fabrication techniques enabling the construction of objects with nanometric features, thus rendering the spatial distribution of the RI to be determined by the designed architectures rather than by their material composition. Conventional nanophotonic devices are designed and fabricated in planar settings, similar to electronic integrated circuits. We present a new class of nanophotonic structures with intricate design in three dimensions inspired by General Relativity concepts. These photonic structures facilitate control over the dynamics of light, through the space curvature of the medium, within which the light is propagating. We demonstrate this concept by studying the dynamics of light near the Schwarzschild radius of an emulated black hole, by fabricating a curved three dimensional surface waveguide that can be mapped to the most famous solution of the Einstein equations: the Schwarzschild space-time, surrounding a massive black hole. We explore the evolution of light in this nano-photonic structure, which allows control over the light evolution: its trajectories, the rate of diffraction, the phase and the group velocities, by manipulating only the spatial curvature. Finally, we demonstrate a phenomenon of tunneling through the bottleneck of the waveguide by transforming guided modes into radiation modes and back. This general method of curved-space structures can serve as the basis for curved nanophotonics: a generic concept for controlling EM waves that can be employed in integrated complex photonic circuits.

We study the stability of an edge state in a photonic analogon of the Su-Schrieffer-Heeger (SSH) system. In this topologically nontrivial model we drive an edge state by a local AC-field. Periodic modulation results in Floquet copies of the edge state in the bandstructure, spaced by the driving frequency around zero energy. We show that for certain driving frequencies the protection of the edge state is destroyed, as it couples to bulk states, although the topological properties of the bulk are unchanged. Theory is verified by experiments in 3D printed evanescently coupled dielectric waveguide arrays.

We demonstrate the experimental realization of a tunable uniform synthetic magnetic flux and the observation of Aharonov-Bohm cages in photonic rhombic lattices. We engineer modulation-assisted tunneling processes that effectively produce non-zero magnetic flux per plaquette. When half a flux quantum per plaquette is realized, all the energy bands collapse into non-dispersive bands and all eigenstates are completely localized. We demonstrate this Aharonov-Bohm caging by observing breathing motions of the optical intensity whose frequency is determined by the energy gaps in the spectrum. The corresponding edge states are shown to be related to the topological edge states of a Creutz ladder.

A finite SSH-chain has two topologically protected edge states for topologically non-trivial dimerization. By adiabatically changing some parameters, these edge states can be transformed into each other (Thouless pump). In between each pump cycle the edge states become delocalized. We investigate how spontaneous commutation of neighboring sites affects the state-exchange. Simulations and calculations show that only one of the edge states is affected by the perturbation. For an experiment, we suggest using evanescently coupled waveguides. We fabricate them by using direct laser writing in polymer to 3D-micro-printing the structure.

We propose and demonstrate a novel technique to probe optical states for long timescales in a photonic lattice by placing it inside a cavity to recycle the state multiple times. The accompanying detection method, which exploits a single-photon detector array, offers quasi-real time-resolved measurements after each round trip. We apply this scheme to intriguing photonic lattices emulating Dirac fermions and Floquet topological phases. We also realize a synthetic pulsed electric field, which can be used to drive transport within photonic lattices. This work opens a new route towards the long-time-detection of slow dynamics and the realization of hybrid analog-digital simulators.

Iridescence has long been considered as an intrinsic special feature in structural colors. But we have also learned that iridescence in structural colors can be reduced by incorporating certain degrees of randomness, as demonstrated by the photonic glass and polycrystals. By studying structural colors in two different groups of spiders – the large, non-iridescent blue tarantulas and the tiny iridescent peacock spiders – we have found examples shown iridescence in structural colors can be both reduced and enhanced through the interaction of sub-micrometer photonic structural features, micrometer-scale geometries, and hierarchies without the needs of randomization.

A building principle of disordered networks leading to brilliant whiteness is described. The model system uses tailored disorder and is compared to an exact model by FDTD calculations. For the artificial model disorder is introduced to a strictly periodic Bragg reflector. The two models show the same optical properties for the visible spectral range. Differences for the near infrared range can be minimized by further introduction of disorder. The found concept allows of fabrication in conventional photoresists as well as in polysaccharide based photoresists after scaling. This artificial model can describe the path from color to whiteness by introducing disorder.

We utilize femtosecond 2-photon lithography for 3D printing of complex microoptical structures. Excellent surface qualities, aberration correction, and low wavefront aberrations can be achieved with resists of different resolution. Blackening by ink-filling and deposition of metals can create stops as well as absorbing hulls. More complex imaging systems that allow for high-angle imaging or telephoto lenses can be created with this technology. Creating a set of resists with different refractive indices and particularly with different index dispersions allows for the combination of two materials in a way that Fraunhofer-type axicons and achromats can be realized. Combining the micro-optics with prisms and mirrors allows side-looking optics. Applications in augmented and virtual reality, imaging, sensing, display and medical technology will be demonstrated.

Industrial High-precision 3D Printing via two-photon absorption (TPA) provides freedom in design for the fabrication of novel products which are not feasible with conventional techniques. Up to now, 2PP-fabrication has only been used for structures on the micrometer scale due to limited travelling ranges of the translation stages and the field-of-view (FoV) of microscope objectives. In this contribution, different strategies for large scale elements are revealed without relying on stitching, e.g. LithoBath3D or scanning by translation stage. Dimensions of optical elements are typically limited to 0.5 mm. This can be overcome by an infinite FoV fabrication and advanced beam steering.

A spherical diffraction limited voxel is highly desirable in multiphoton polymerization (MPP) technology. Voxel having 1:1 aspect ratio could significantly enhance the final resolution of the fabricated structures in many applications (e.g. photonics) where the voxel axial resolution, and not the transversal size is often the limiting factor. Currently, 1:3 aspect ratio is typical for MPP. In order to improve it the more advanced focusing techniques are required. Inheriting from the microscopy, we employed two opposing high NA microscope objectives in order to create 4Pi excitation of the photopolymer. Here, we present the first results of 4Pi multiphoton polymerization.

The fabrication of 3D micro- and nanostructures composed of many dissimilar ingredient materials is interesting and challenging. Towards this goal, we have integrated a microfluidic system into a commercial 3D laser micro-printing system that can handle all different required photoresists and solvents (up to ten chemicals). As a demanding example, we demonstrate a 3D fluorescent security feature composed of five different photoresists, four fluorescent with different colors and one non-fluorescent. The two solvents for development are also delivered via the microfluidic system, such that the sample does not leave the microfluidic system during the entire 3D printing process.

Femtosecond laser based 3D nanolithography is gaining popularity in huge variety of fields. However, further improvements are needed to push it from laboratory level use into a wide spread adaptation. In this work we present several advances needed to achieve this goal. First, linear stage and galvo-scanners synchronization is employed to produce stitch-free mm-sized structures with features down to micrometers. Furthermore, it is shown that by varying objective numerical apertures (NA) from 0.8 NA to 1.4 NA voxel size can be tuned in the range of 330 nm to 1.7 µm in transverse and 1.9 µm to 7.9 µm in longitudinal directions, resulting in voxel volumes from 0.017 µm^3 to 3.759 µm^3 with structuring rates at 2426 µm^3/s and 104767 µm^3/s respectively at 1 cm/s translation velocity. This two orders of magnitude tunability is exploited to fabricate various functional structures. It includes 2 mm diameter functional micro-lens, cantilever capable of sustaining multiple deformation cycles and free-movable micromechanical spider and squid (overall size - up to 5 mm), showing possibility to print true 3D hinge-like microstructures (feature size down to micrometers) for possible uses in microrobotics. Overall, the presented results show simple and straight-forward way to combine resolution on-demand and stitch-free 3D laser lithography for functional structure fabrication needed for fast expanding science and/or engineering fields.

The performance of microlenses fabricated via femtosecond direct laser writing is insuperably limited with regards to image contrast within its all-transparent material system. Our proposed super-fine inkjet process for the realization of apertures and non-transparent hulls both shields stray light and adds additional optical design parameters, namely diameter, shape, and position of the aperture. A micropinhole camera, a high-contrast imaging microlens, and a telecentric system are demonstrated. Our method is most suitable for 3D-printed micro-optics due to its one-step integration and auto-adjustment of the aperture position and can be useful for highly precise integration of functional materials beyond mere non-transparency.

We report the fabrication of 3D photoactivator-free proteinaceous microstructures by a liquid-immersion-lens configuration of femtosecond laser-induced cross-linking. Laser-induced cross-linking of protein is an attractive method to create proteinaceous structures providing complex biomimetic 3D microenvironment. Liquid-immersion-lens laser direct write enhances the homogeneity of created proteinaceous microstructures with nearly arbitrary designs by maintaining the same exposure conditions . The aspect of photo- activator-free fabrication is crucial for medical and biological applications where even the slightest traces of impurities bring about a risk. We believe that the creation of pure proteinaceous microstructures from a vast diversity of available proteins offers many applications in lab-on-a-chip and total analysis systems.

Additive manufacturing – specifically 3D laser lithography – is a powerful technology for the fabrication of functional devices on the micro- and nanoscale. This technique has already been applied in a broad range of fields, including metamaterials, biomedicine, and others. While significant progress has being made in chemically tailored photoresist systems for additive manufacturing, the design of photoresists allowing for subtractive manufacturing on the microscale is still in its infancy. Existing resists for 3D laser lithography can only be removed under harsh cleavage conditions. Herein, we present a new class of on-demand cleavable photoresists for 3D laser lithography employing mild conditions.

We introduce an approach to microstructures prepared via 3D laser lithography, with the final aim to reversibly adjust the mechanical properties by different colours of light. By embedding a radical crosslinker based on an anthracene dimer into an otherwise standard photoresist, we impart photoresponsive mechanical behaviour to the 3D microstructures. Different wavelengths of light, addressing the anthracene units within, allow dynamically altering the number of crosslinks constituting the microstructures. Thus, the mechanical properties of the structures should be adjustable by disparate colours of light. Ultimately, we wish to use the inherent fluorescence of the monomeric anthracene units within the structures to read out the mechanical properties by optical means.

We present a photoresist system for the fabrication of three-dimensional hetero-microstructures based on poly(N-isopropylacrylamide). A gray-tone lithography approach is used to locally control the material parameters in a single production step of two-photon laser lithography. We thus establish active structures that exhibit a well-defined and large-amplitude actuation in response to temperature changes. The flexibility of the fabrication method enables the generation of complex actuation patterns, which are in very good agreement with numerical calculations. Critically, we show that the response of the microstructures can also be triggered locally by photo-thermal conversion of focused light.

While there is great interest in 3D printing for microfluidic device fabrication, the challenge has been to achieve feature sizes that are in the truly microfluidic regime (<100 μm). The fundamental problem is that commercial tools and materials, which excel in many other application areas, have not been developed to address the unique needs of microfluidic device fabrication. Consequently, we have created our own stereolithographic 3D printer and materials that are specifically tailored to meet these needs. We show that flow channels as small as 18 μm x 20 μm can be reliably fabricated, as well as compact active elements such as valves and pumps, resulting in highly integrated microfluidic devices as small as a few cubic millimeters.

Microchannels in fused silica have attracted much attention for their broad range of applications in microfluidics. We proposed to combine temporally shaped (double-pulse train) laser pulses with spatially shaped (Bessel beam) laser pulses. Through irradiation with a temporally shaped femtosecond laser Bessel beam, modification efficiency was improved by adjusting the pulse delay. By combining the FLICE method with a temporally shaped Bessel beam, high-throughput microchannels fabrication were achieved. The mechanism of etching depth enhancement was elucidated by localized transient free electrons dynamics-induced structural and morphological changes.This method enables high-throughput and high-aspect-ratio microchannels fabrication in fused silica for potential application in microfluidics.

Predictive visualisation of laser-processing of materials is challenging, as the nonlinear interaction of light and matter is complicated to model. Here, we demonstrate a visualisation approach that relies entirely on a neural network and uses training data obtained via laser machining using a digital micromirror device (DMD) as a spatial light modulator. The technique is able to generate a predicted surface image and 3D depth profile of the ablated surface for a wide range of beam shapes. The predicted visualisations are remarkably effective and almost indistinguishable from real experimental data in appearance.

Additive manufacturing of optical elements with its layered process brings challenges concerning the homogeneity of the material. Depending on the printing process local variations of the refractive index might occur within or between the layers. Using the Scanning Focused Refractive Index Microscopy the distribution of the refractive index within and between the layers is analyzed. The purpose of the presentation is to give a detailed insight into refractive index measurements at the layer interfaces of elements created by additive manufacturing while summarizing the used printing technologies. Possible use cases of the refractive index distributions within the part are also discussed.

This paper presents new methods to achieve parallel nanofabrication and high-resolution multi-photon imaging based on temporal focusing, i.e., the spectrum of a femtosecond laser is spatially separated by a DMD and recombined by an objective lens, forming a-depth resolved light sheet for laser micromachining and multi-photon imaging. Examples of high-throughput nanofabrication will be given in two-photon polymerization processes and 3-D metal printing, achieving a resolution of 500 nm. In terms of imaging, a new two-snapshot structured light illumination (SLI) reconstruction algorithm for fast image acquisition will be reported, demonstrating improved improved axial resolution on a temporal focusing fluorescence microscope.

Additive Manufacturing (or 3D printing) is increasingly used in the production of biomedical implants. In particular, there is a growing research interest in using additive manufacturing for producing scaffolds for advanced tissue engineering constructs. This interest originates from the possibility to build 3D structured scaffolds with a user-defined macrostructure and porosity. This enables the production of 3D objects with tuneable mechanical properties and pore sizes, and opens up the possibility to produce patient specific implants. This presentation will focus on my group's work in laser-based additive manufacturing of tissue engineering scaffolds and the use of these structures in healthcare applications for regeneration of both soft and hard tissues.

Adaptive3D is developing a materials, hardware, software and supply-chain solution for a leading auto manufacturers to rapidly produce high-volume, low-cost car seat cushions with internally complex micro-truss structures resulting in polymer parts with sufficient materials properties necessary to withstand the application demands of the automotive industry. Pursuit of this solution will mature the business and technology ecosystems necessary to deliver additively manufactured polymeric parts that compete on cost and time with injection molding and extrusion to produce lighter and stronger car seats for next-generation vehicles. The technology is built upon recent advances in photo-patterning thiol-based resins using massively scaled digital micromirror device systems. Our solution results in engineering foam-like structures with specific morphologies using custom software, iterating materials design, part design and equipment design in combination to arrive at a tailored manufacturing solution driven by patterned light.

Recent development of high-resolution Micro-Continuous Liquid Interface Production (microCLIP) process has enabled 3D printing of biomedical devices with 10 micron-scale precision. 3D bioresorbable vascular scaffolds (BVS) were printed using an antioxidant, photopolymerizable citric acid-based material (B-InkTM). To improve lingering challenges (material strength/stiffness), a PLLA nanophase (2wt.%) was dissolved and secondary initiators were added to the photopolymer resin to improve post-process polymerization. This greatly improved bulk material stiffness and yielded BVSs with 100um strut thickness that could sustain necessary biological radial pressure loadings. This technology and material is a large step forward toward on-the-spot and on-demand fabrication of patient specific BVSs.

This paper presents a holographic fabrication of a new type of photonic crystal, called graded photonic super-crystals with graded basis, dual period and dual symmetry. Pixel-by-pixel phase coding of laser beams in a spatial light modulator can produce the highest resolution in produced photonic super-lattice. Two-level designs in phase pattern are used to generate graded photonic super-crystals where graded square lattice clusters are orientated in four, five or six-fold symmetry. Further phase engineering in a super-cell of 12x8 pixels can produce small-period square lattice orientated in a large period rectangular pattern.