Davide Janner

Politecnico di Torino | polito · DISAT - Department of Applied Science and Technology

Microplastics (MPs) are a heterogeneous group of solid polymers with dimensions <5 mm, which are a widespread contaminant of the environment. Their ubiquitous presence grabbed researchers' attention in the last decade, and the problem of MPs detection and quantification is currently a topic of utmost importance. Most identification and quantificati...

Controlled wetting of metallic surfaces is highly interesting in many practical applications, from self-cleaning to drag reduction. Laser processing to obtain micro-/nano-textured surfaced to obtain superhydrophobic has mainly leveraged expensive and low throughput pico-/femto-second ultrashort pulse lasers. In this study, we demonstrate the micro/...

Microplastics are solid plastic particles composed of different polymers whose dimensions are less or equal to 5 mm. They originate either from primary production or, more frequently, by degradation of plastic materials. Given their interaction with the ecosystems, and their longlived persistence in the environment, they pose a significant threat t...

Bioresorbable phosphate glasses are an excellent alternative to conventional silicate-based glass systems for biomedical applications. These glasses can have tailorable bioresorbability and mechanical properties, a wide range of transparency windows (from 300 to 2600 nm), and are of great interest for biophotonic devices. The present work investiga...

Nanogratings (NGs) are self-assembled subwavelength and birefringent nanostructures created by femtosecond laser direct writing (FLDW) in glass, which are of high interest for photonics, sensing, five-dimensional (5D) optical data storage, or microfluidics applications. In this work, NG formation windows were investigated in nine commercial glasses...

Nanogratings are self-organized and sub-wavelength birefringent structures that are formed upon the action of high intensity ultrashort light pulses in the bulk of a transparent material. They have found interest in optics/photonics, microfluidics, optical data storage or sensing applications. However, the ability to successfully imprint 3-dimensio...

Glass-to-metal interfaces play a crucial role in the robustness and the mechanical integrity of solid oxide cells, and it is well known that a sound interface improves the mechanical reliability of the whole stack. The present work focuses on the torsional behaviour of hourglass-shaped Crofer 22 APU stainless steel joined by a glass sealant specifi...

Passive energy‐conversion devices based on water uptake and evaporation offer a robust and cost‐effective alternative in a wide variety of applications. This work introduces a new research avenue in the design of passive devices by replacing traditional porous materials with rigid capillary layers engraved with optimized V‐shaped grooves. The conce...

The surface modification of bioactive glasses significantly impacts their performance for in-vivo biomedical applications. An affordable nanosecond pulsed laser surface-modification technique would provide great flexibility in applications such as cell scaffolding and fouling/anti-fouling engineered surfaces. This study reports on an infrared nanos...

The ability to induce nanogratings using a femtosecond laser in common oxide glasses is investigated experimentally. A simple and general viscosity-based approach is subsequently employed to predict their existence in glass.

Recent developments in sensors are pushing for optimized materials that can increase their usage, bolster their sensitivity and enable new and more efficient transduction mechanisms. We hereby review some of the most relevant applications of glasses and glass–ceramics for photonic sensors considering the recent trends and innovative approaches. Thi...

Recently developed calcium-phosphate glass formulations are proposed in this chapter as a new class of materials for biomedical optics and photonics. The glasses have been designed and carefully prepared in our laboratory to be dissolvable in biological fluids while being optically transparent, mechanically reliable both in dry and humid environmen...

Ion-exchange in molten nitrate salts containing metal ions (i.e. silver, copper, etc.) represents a well-established technique able to modify the chemical-physical properties of glass materials. It is widely used not only in the field of integrated optics (IO) but also, more recently, in plasmonics due to the possibility to induce the formation of...

This work investigates the role of a B 2 O 3 addition (up to 21 mole %) into a lithium niobium silicate glass matrix, focusing on the orientational dependency of second harmonic generation (SHG), induced after femtosecond laser irradiation. We detected the sharp emission of light at 515 nm, characteristic of SHG, in both static and scanning configu...

Femtosecond (fs)-laser direct writing is a powerful technique to enable a large variety of integrated photonic functions in glass materials. One possible way to achieve functionalization is through highly localized and controlled crystallization inside the glass volume, for example by precipitating nanocrystals with second-order susceptibility (fre...

This review focuses on the recent advances in lossy more resonance (LMR) fiber optics sensors. LMR sensors present many interesting feature also in comparison with surface plasmon resonance (SPR), the most widespread resonance-based sensing platform. Two key parameters determine LMR sensors performance: their geometrical configuration and the mater...

The Langmuir–Blodgett technique, in which a layer of nanoparticles is spread at the water/air interface and further transferred onto a solid support, is a versatile approach for the preparation of SERS substrates with a controllable arrangement of hotspots. In a previous work, we demonstrated that fine-tuning the lateral packing and subsequent seed...

Bone-tissue regeneration induced by biomimetic bioactive materials is the most promising approach alternative to the clinical ones used to treat bone loss caused by trauma or diseases such as osteoporosis. The goal is to design nanostructured bioactive constructs able to reproduce the physiological environment: By mimicking the natural features of...

We present an experimental characterization of the amplification of sub-nanosecond duration laser pulses at a wavelength of 1538 nm in short custom-made Er:Yb phosphate glass fibers with different core diameters. The fibers vary in their diameter from 100 µm (highly multi-mode) down to 12 µm (single-mode). The peak power, energy per pulse, and spec...

We report on the design and development of microstructured phosphate glass optical fibers for minimally invasive diagnosis and therapy. We discuss preliminary results of fiber drawing and characterization.

The steps toward the fabrication of directly‐extruded microstructured fiber preforms made of a bioresorbable phosphate glass are herein presented, analyzing the features of the process from the glass synthesis to the manufacturing of the fiber. The realization of these fibers leverages on three main pillars: an optically transparent bioresorbable g...

The combination of fiber-optic–based platforms for biosensing with nanotechnologies is opening up the chance for the development of in situ, portable, lightweight, versatile, reliable and high-performance optical sensing devices. The route consists of the generation of lossy mode resonances (LMRs) by means of the deposition of nm-thick absorbing me...

The aim of this study was to fabricate a bioactive optical fiber able to monitor “in situ” its reaction with the body through changes in its optical properties. Core and clad preforms were prepared with the composition (97.25*(0.50P2O5‐0.40SrO‐0.10Na2O)‐2.5ZnO‐0.25Er2O3) and (98.25*(0.50P2O5‐0.40SrO‐0.10Na2O)‐1.75ZnO) (in mol%), respectively, and s...

Optical fibers have recently attracted a noticeable interest for biomedical applications since they provide a minimally invasive method for in‐vivo sensing, imaging techniques, deep‐tissue photodynamic therapy or optogenetics. The silica optical fibers are the most commonly used because they offer excellent optical properties and they are readily a...

Thanks to its very high solubility of laser-active rare earth ions and outstanding thermo-mechanical properties, phosphate glass host represents a genuine alternative to the more traditional and employed silica glass platform to develop compact active devices, such as lasers and amplifiers. In particular, multicomponent phosphate glasses can withst...

Nanoparticle self-assembly is a robust and versatile strategy for the development of functional nanostructured materials, offering low-cost and scalable methods that can be fine-tuned for many different specific application. In this work, we demonstrate a pathway for the fabrication of tailorable quasi-two-dimensional lattices of gold nanoparticles...

Titania particles doped with various concentrations of Erbium were synthesized by the sol-gel method followed by different heat treatments. The shape and the grain growth of the particles were noticeably affected by the concentration of Erbium and the heat treatment conditions. An infrared emission at 1530 nm, as well as green and red up-conversion...

Photosensitivity of phosphate optical fibers at 193 nm is combined with bioresorbability in the prospect of developing multifunctional optical fiber probes for theranostic. Dissolution of the fiber in PBS is reported showing differential etching.

In recent years, the exploitation of compact laser sources and amplifiers in fiber form has found extensive applications in industrial and scientific fields. The fiber format offers compactness, high beam quality through single-mode regime and excellent heat dissipation, thus leading to high laser reliability and long-term stability. The realizatio...

We report on recent developments in the field of bioresorbable phosphate optical fibers for biomedicine. Preliminary results for fiber Bragg grating inscription in a single-mode bioresorbable fiber, using femtosecond laser system, are presented and discussed.

Phosphate glasses (PGs) are promising host materials for the development of compact fiber amplifiers and lasers thanks to their good chemical durability, easy processing, outstanding optical properties, no clustering effect and very high solubility of rare-earth (RE) ions. Furthermore, some particular calcium-phosphate glasses exhibit unique dissol...

In the last years bioresorbable materials are gaining increasing interest for building implantable optical components for medical devices. In this work we show the fabrication of bioresorbable optical fibers designed for diffuse optics applications, featuring large core diameter (up to 200 μm) and numerical aperture (0.17) to maximize the collectio...

Er-doped phosphate glass ceramics were fabricated by melt-quenching technique followed by a heat treatment. The effect of the crystallization on the structural and luminescence properties of phosphate glasses containing Al2O3, TiO2, and ZnO was investigated. The morphological and structural properties of the glass ceramics were characterized by Fie...

Er-doped phosphate glasses were fabricated by melt-quenching technique. The changes in their thermal, structural and luminescence properties with the addition of Al2O3, TiO2 or ZnO were studied. Physical and thermal properties were investigated through density measurement and differential thermal analysis. Structural characterization was performed...

Graphene on a z-cut LiNbO3 pyroresistive platform allowing infrared light detection is reported by Frank H. L. Koppens, Valerio Pruneri, and co-workers in article number 1600723. Light is absorbed in the LiNbO3 crystal substrate and the subsequent temperature increase, via the pyroelectric effect, induces polarization (bound) charges at the crystal...

Phosphate glass optical fibers were designed and fabricated for applications in the fields of remote sensing and biomedicine. Main results are reported together with the recent developments.

Environmental contextTransmission of viruses is related to their survival while being outside the host body. By means of experimental and computational simulations we assess the optimal conditions for virus deactivation upon contact with particularly functionalised substrates. These results constitute the basis for the design of new surfaces with h...

Mid-infrared (mid-IR) photo-detection has been recently growing in importance because of its multiple applications, including vibrational spectroscopy and thermal imaging. We propose and demonstrate a novel pyro-resistive photo-detection platform that combines a ferroelectric substrate (a z-cut LiNbO3 crystal) and a graphene layer transferred on to...

Direct deposition of graphene on substrates would avoid costly, time consuming and defect inducing transfer techniques. In this paper we used ultrathin films of Ni, with thickness ranging from 5 to 50 nm, as a catalytic surface on glass to seed and promote chemical vapor deposition (CVD) of graphene. Different regimes and dynamics were studied for...

Surfaces contaminated with pathogenic microorganisms contribute to their transmission and spreading. The development of "active surfaces" that can reduce or eliminate this contamination necessitates a detailed understanding of the molecular mechanisms of interactions between the surfaces and the microorganisms. Few studies have shown that, among th...

Direct deposition of graphene on substrates would avoid costly, time consuming and defective transfer techniques. In this paper we used ultrathin films of Ni, with thickness ranging from 5 to 50 nm, as a catalytic surface on glass to seed and promote chemical vapor deposition (CVD) of graphene. Different regimes and dynamics were studied for variou...

Infrared spectroscopy provides chemical information of biomolecules by detecting their vibrational fingerprints. Here, we use graphene plasmons to enhance infrared absorption and to demonstrate a tunable biosensor with high sensitivity for label-free and chemically-specific detection of protein monolayers. We show that the tunability and extreme li...

Opto-electronic devices utilizing graphene have already demonstrated unique capabilities, which are much more difficult to realize with conventional technologies. However, the requirements in terms of material quality and uniformity are very demanding. A major roadblock towards high-performance devices are the nanoscale variations of graphene prope...

Supplementary Figures 1-10, Supplementary Notes 1-2 and Supplementary References

We demonstrate a graphene infrared biosensor for chemical-specific label-free protein detection. Graphene plasmon resonances are dynamically tuned to enhance protein vibrational bands. We show that the extreme light confinement makes graphene plasmons extremely sensitive to nanometric molecules.

Infrared spectroscopy is the technique of choice for chemical identification of biomolecules through their vibrational fingerprints. However, infrared light interacts poorly with nanometric-size molecules. We exploit the unique electro-optical properties of graphene to demonstrate a high-sensitivity tunable plasmonic biosensor for chemically specif...

Future optoelectronic devices and their low cost roll-to-roll production require mechanically flexible transparent electrodes (TEs) and substrate materials. Indium tin oxide (ITO) is the most widely used TE thanks to its high optical transmission and low electrical sheet resistance. However ITO, besides being expensive, has very poor performance un...

We will review the current status of domain inverted lithium niobate acousto- and electro-optic devices and show how the introduction of domain micro-engineering techniques can have a strong impact on modulators' performance enabling for a new class of integrated devices. We will also present potential applications of the proposed devices in increa...

We will present SixSenso’s low cost and portable devices for measuring scattering, reading microarrays, detecting and counting microorganisms, cells and particles, by exploiting full field of view CMOS or CCD at the highest resolution.

We demonstrate experimentally a scheme to measure small temporal delays, much smaller than the pulse width, between optical pulses. Specifically, we observe an interference effect, based on the concepts of quantum weak measurements and weak value amplification, through which a sub-pulsewidth temporal delay between two femtosecond pulses induces a m...

The current status of domain inverted lithium niobate acousto- and electrooptic devices is reviewed. We introduce the main domain microengineering techniques and their impact on modulators' performance in terms of reduced power consumption and enablers for a new class of integrated devices. We will then review potential applications of the devices...

We report the presence of surface acoustic wave (SAW) band gap on acoustic superlattice (ASL) in a single-crystal lithium niobate structure. The band gap behavior is determined by calculating the SAW band structure and also by simulating the transmission of an acoustic wave through a finite length section of ASL using finite element analysis. The c...

LiNbO3 is a crystal widely used in photonics and acoustics, for example in electro-optic modulation, nonlinear optical frequency conversion, electric field sensing and surface acoustic wave filtering. It often needs to be combined with other materials and used in thin layers to achieve the adequate device performance. In this paper, we investigate...

We show that an appropriate mass-loading, placed on the surface and in between the electrodes of a coplanar acoustic LiNbO3 superlattice, can counteract lateral diffraction of surface acoustic waves (SAWs). The strong confinement corresponds to a SAW mode, whose displacement is measured using laser interferometry. The proposed SAW confinement metho...

Optical high-voltage sensors have outstanding advantages in terms of isolation and immunity to electromagnetic interference. So far, several configurations have been proposed, mostly based on integrated Mach-Zehnder interferometers [1] or polarization/phase rotation in piezo-electric crystal [2]. While the first scheme requires initial electrical b...