This study investigates the Candida albicans biofilm formation on different phases of titanium dioxide (TiO2) and titanium disulfide (TiS2) directly grown on titanium substrates. The Candida albicans growth is evaluated by counting the cells in media and surface as well as using colorimetric XTT assays for evaluating biofilm formation. Also, the viability and adhesion of human gingival fibroblast cells to the material's surface is investigated to show the non-toxicity and cell adhesion to these surface. TiS2 nanoflakes growth from titanium substrates showed significant improvement in both the cell attachments and antimicrobial effect.

Periodic arrangements of micro- and nano-holes with controllable period, diameter and depth at the surface of materials are of high interest for a large range of applications. Here we present a laser-based approach using micro-Bessel beams with adjustable length to machine arrays of holes with subwavelength diameters and depths reaching several micrometers at the surface of fused silica. Suitability and limitations of the technique are investigated, including the challenge of avoiding crosstalk effects. The performance level shows the potential of the direct-laser-processing method towards the realization of integrated devices, as a flexible and cost-effective alternative technique to current multistep nanofabrication methods.

Using recently developed laser-assisted synthesis technique (LAST), we demonstrate, for the first time, transient absorption (TA) exciton dynamics of W- and Mo-families of TMDs that have strong excitation fluence dependence and reach extremely long, several nanosecond lifetimes at the highest fluences. To put this in the context, all previous observations have shown tens of picosecond lifetimes at high powers (due to Auger recombination). Using a variety of experimental approaches (excitation wavelength and temperature dependent measurements) and comparing the results with TMD samples in a freestanding form, we trace our observations to the amount of strain produced in the LAST samples by the specifics of high temperature growth and substrate cooling. Using kinetic modeling, we relate these observations to the strain-induced modifications of electronic bands and associated population of intervalley dark excitons that can now interplay with intravalley (bright) excitations.

Substitutional defects in 2D materials present unique opportunities for optoelectronic and quantum information platforms. This paper will introduce two types of substitutional defects. The first type is atomic substitution: a nitrogen atom substituting a chalcogen atom in 2D transition metal dichalcogenides (TMDs), which yields new photoluminescence features [1]. The second type is layer substitution: an entire layer of chalcogen atoms in 2D TMD substituted by another type of chalcogen atoms, namely, Janus TMDs. Janus TMDs form unconventional interaction with adjacent materials [2,3]. [1] ACS Nano, 16(5), 7428 (2022). [2] JACS, 142(41), 17499 (2020). [3] ACS Nano, 15(9), 14394 (2021).

2D materials like transition metal dichalcogenides (TMDCs) are promising materials for the next generation of flexible devices. With low-temperature Atomic Layer Deposition a direct large area deposition of these materials on temperature sensitive substrates becomes possible. Due to these substrates conventional post- and further processing methods, like thermal annealing, are not suitable. With the usage of ultrashort pulsed Laser a moification of these films with very small heat-affected zones can be done. This allows a selective increase of crystallinity in amorphous MoS2 films or phase engineering between the metallic and semiconducting phase in MoS2 independent of the growing substrate.

Automated platforms for synthesis are a necessity to increase the rate of discovery, synthesis, and optimization of materials to match the accelerating pace of theoretical predictions. Here, we introduce a novel pulsed laser deposition (PLD) platform that combines in situ Raman, photoluminescence, and white light reflectance spectroscopies as a material probe with intensified CCD (ICCD) imaging/spectroscopy and ion probe gas-phase PLD plume diagnostics. These diagnostics together with full automation and high-throughput synthesis schemes enable rapid synthesis and characterization with a Python-based dataflow for seamless integration with machine learning algorithms. Examples of in situ spectroscopy of 2D materials during growth and modification will be discussed.

Recently, this plasmon-assisted photocatalytic effect was shown to be predominantly associated with the heating induced by illumination [Faraday Discuss. 2019; Chem. Sci. 2020]. This pure thermal interpretation was based initially on our self-consistent theory of the electron distribution under continuous-wave illumination [Light: Sci. Appl. 2019]. This result was corroborated by independent thermal calculation [Chem. Sci. 2020, Nanoscale 2020, ACS Photonics 2021]. We further extended our developed model to study the importance of nonlinear photothermal effects in plasmon-assisted photocatalysis experiments [Nanoscale 2022]. This shows that any claim for dominance of non-thermal electrons in plasmon-assisted photocatalysis must account for this photothermal nonlinear mechanism.

Single photon emitters (SPE) are essential building blocks for proposed quantum technologies. An ideal SPE emits only one photon at a time and the photons are indistinguishable. CdSe core/shell quantum dots (QDs) provide a physical system that approximates a SPE. We discuss progress to improve the SPE properties of CdSe QDs. We present synthesis and spectroscopic analysis of wurtzite-CdSe/CdS, mixed shell CdSe/Cd_0.5Zn_0.5S, and continuously graded CdSe/Cd_xZn_1-xSe/ZnSe_yS_1-y QDs. We compare their behaviors at room and cryogenic temperatures using photoluminescence spectroscopy, Michelson interferometry, and Hanbury Brown and Twiss interferometry. We also address efforts to mitigate undesirable behaviors observed in QDs such as charging.

A novel additive nanomanufacturing (ANM) technique capable of dry-printing functional materials and devices with high electrical and mechanical performances is presented in this talk. The mechanical behavior of the ANM-printed silver lines on polyimide substrates under bending and cycling tests up to 1 million cycles at different bending radii is studied. The results show that ANM-printed silver lines have nearly no change in resistivity even after 1 million bending cycles. These tests validated its good electrical conductivity and functionality of the printed devices under different strain which makes the ANM as a potential technique for printing flexible electronics and devices.

This work presents the use of 3D printing by two-photon polymerization (2PP) to fabricate photonic nanojet (PNJ)-generating structures from a hybrid material developed in-house. Since 2PP enables true 3D processing of photoresists at the microscale with sub-100 nm resolution, it is possible to print highly complex structures without any limitation in their geometry. Thus, 2PP paves the way to investigate novel PNJ-generating structural designs and combine classic ones with standard focusing elements, respectively. Simultaneously, 2PP provides a high potential for developing real-world products for PNJ applications due to its simple sample processing that does not require any vacuum atmosphere, harsh chemicals, and cleanroom environment. In this way, novel PNJ-generating structures can be easily integrated into macroscopic supporting frames. Those frames could then be used for super-resolution imaging of samples.

Printing pure and multimaterial structures and devices in a single process is still in its infancy. Current electronic printing are ink-based technologies that suffer from ink contaminations, complex ink formulation, and limited sources of printing ink making it difficult to print pure and multimaterial structures and devices. Here, for the first time, we report a novel dry multimaterial 3D printing technology which allows printing multiple materials such as barium titanate (BTO), titanium dioxide (TiO2), tin oxide (SnO), zinc oxide (ZnO), aluminum oxide (Al2O3) and silver (Ag) on flexible substrates in a single step process. Flexible ZnO-based photodetectors and flexible electronics are printed and tested to demonstrate the huge impact of this technology on the future of printed electronics, sensors, and energy devices.

3D printing by two-photon polymerization (2PP) enables a straightforward solution to fabricate highly complex structures with a resolution down to sub-100 nm cost-effectively, which is why the technique has recently emerged as an up-and-coming manufacturing approach in photonics, optics, mechanics, and biomedicine. This work describes, therefore, recent studies using 3D printing by 2PP in the research area mentioned. In this context, novel 3D designs, postprocessing methods, and photoresists will be presented to tailor the optical or mechanical properties of printed structures and photoresists. Combined with recent optimizations of the 2PP process, 3D printing at the micro- and nanoscale paves the way to develop real-world products in the future, such as biomedical implants or novel devices using free-form optics and metamaterials.

The use of printed electronics is rising fast as we move toward the internet of things (IoT). Today, most printed electronics are printed on nonbiodegradable polymers resulting in an exponential increase in E-waste formation. The current printing technologies are liquid/ink-based which are not compatible with biodegradable substrates such as papers. Here, we introduce a novel dry printing method to print conductive silver patterns on biodegradable papers. The effect of different printing parameters on the paper burning threshold is investigated, and the electrical characteristics of the lines are characterized for different line thicknesses and widths. Furthermore, the mechanical properties of the lines are studied by bending, twisting, and adhesion tests. This dry printing technology can pave the way toward eco-friendly and biodegradable papertronics.

In the area of optoelectronics, Epsilon Near Zero (ENZ) materials possess a special place, as due to them, high nonlinearities can be achieved. Our interest is focused at the telecommunication wavelengths, as a lot of nanophotonic phenomena are taking place. Transparent Conductive Oxides (TCOs) is a group of materials that are used in the ENZ regime. Aluminum Zinc Oxide (AZO) is a TCO that has been proved that is preferred for telecom applications. In order to achieve higher nonlinearities in ENZ regime, we fabricate 3D photonic nanostructures, via Multiphoton lithography and we cover them with AZO via Pulsed Laser Deposition.

This presentation was prepared for SPIE LASE 2023.

In this presentation, I show how we have been using a particularly sensitive and simple quantitative phase microscopy technique(QPM) technique called cross-grating phase microscopy (CGM) for applications in nanophotonics, opening a new route of investigation for QPM, besides biology. This contribution is aimed to explain (i) how CGM can be used as a temperature microscopy technique to map the temperature of gold nanoparticles under illumination, enabling applications in physics, chemistry and biology at the nano/microscale; (ii) how CGM can map the complex optical conductivity and complex refractive index of 2D materials; (iii) how CGM can retrieve the complex optical polarizability of nanoparticles, along with the extinction, scattering and absorption cross sections from a single interferogram image, and finally (iv) how CGM can fully characterize metasurfaces.

This presentation was prepared for SPIE LASE 2023.

We present here a new kind of laser microcavity to be used as a biosensor. It is based on dielectric pillar fabricated by photolithography with a negative photoresist resist, transparent and having a high index in the visible. The pillars are infiltrated by colloidal core/shell CdSe/CdS nanocrystals or nanoplatelets with appropriate surface ligands so that the nanoemitters get into the pillars, but remain close to the surface and homogeneously dispersed. The nanoemitter fluorescence excite whispering gallery resonant modes. We present here numerical and experimental results demonstrating the quality of the pillars and evidencing the resonant modes.

Nonlinear optics (NLO) is a well-established research field, which has benefited from plasmonics and nanoplasmonics to enhance nonlinear optical processes in bulk and nanomaterials. Another subject which has grown in the last few years and employs plasmonic enhancement are the field of nanolasers and random lasers. In this talk, I shall briefly review the basics concepts of plasmonics and nanoplasmonics, and spend most of the time giving recent examples of nanoplasmonics in NLO using gold nanorods and gold metasurfaces, as well as plasmonically enhanced nano and random lasers, with the last one exploiting rigid and flexible random lasers geometries.

Pulsed laser ablation in liquids (LAL) is a growing field for the generation of metallic nanoparticles, but a comprehensive picture of the fundamental mechanisms is still missing. Material ejection, shock wave, and cavitation bubble dynamics are investigated by high-speed photography with speckle-free illumination at exposure times below 100 ps using a novel light source that is based on amplified spontaneous emission within a femtosecond laser pumped Rhodamine dye cell. Framing rates at up to 1 MHz and accurate triggering even make it possible to capture the bubble collapse at LAL.

Laser implantation can be used for the incorporation of metal nanoparticles into a dielectric matrix. To this end, a thin gold coating on a silicon suboxide (SiOx, x < 2) film is irradiated with a nanosecond laser resulting in the formation of gold nanoparticles in this SiOx-film. By thermal treatment, Si quantum dots are formed by a phase separation of SiOx into Si and SiO2. These Si quantum dots exhibit visible-NIR photoluminescence, which is significantly enhanced through the coupling with the nearby plasmonic gold particles. A more than twofold enhancement is obtained.