In order to enable optical systems to operate with a high degree of compactness and reliability it is necessary to combine large number of optical functions in small monolithic structures. A development, somewhat reminiscent of that that took place in Integrated Electronics, is now beginning to take place in optics. The initial challenge in this emerging field, known appropriately as "Integrated Optics", is to demonstrate the possibility of performing basic optical functions such as light generation, coupling, modulation, and guiding in Integrated Optical configurations. The talk will review the main theoretical and experimental developments to date in Integrated Optics. Specific topics to be discussed include: Material considerations, guiding mechanisms, modulation, coupling and mode losses. The fabrication and applications of periodic thin film structures will be discussed.

Integrated optics

Fluorescent nanodiamond is a new nanomaterial that possesses several useful properties, including good biocompatibility1, excellent photostability1,2 and facile surface functionalizability2,3. Moreover, when excited by a laser, defect centres within the nanodiamond emit photons that are capable of penetrating tissue, making them well suited for biological imaging applications1,2,4. Here, we show that bright fluorescent nanodiamonds can be produced in large quantities by irradiating synthetic diamond nanocrystallites with helium ions. The fluorescence is sufficiently bright and stable to allow three-dimensional tracking of a single particle within the cell by means of either one- or two-photon-excited fluorescence microscopy. The excellent photophysical characteristics are maintained for particles as small as 25 nm, suggesting that fluorescent nanodiamond is an ideal probe for long-term tracking and imaging in vivo, with good temporal and spatial resolution.

Mass production and dynamic imaging of fluorescent nanodiamonds

Hematite (α-Fe2O3), with a bandgap suitable for absorption of the solar spectrum, is ideally suited for use as a photoanode material in photoelectrochemical (PEC) conversion of solar light into hydrogen fuel via water splitting. However, low hole mobility, short hole lifetime, high density of surface states, and slow kinetics for oxygen evolution at the α-Fe2O3/electrolyte interface have limited the PEC performance of α-Fe2O3 photoanodes to date. Along with numerous reports on doping and nanostructuring of α-Fe2O3, increased attention has been paid to α-Fe2O3 heterostructure design for improved PEC performance. This review article provides an overview of four main approaches to rational heterostructure design: coupling α-Fe2O3 with (1) an n- or p-type semiconductor for promoting charge separation; (2) a nanotextured conductive substrate for efficient charge collection; (3) a surface/interface passivation layer for reduced surface/interface charge recombination; (4) a catalyst for accelerated water oxidation kinetics. The achievements to date demonstrate that high PEC performance may be accessed with these designs. In addition, we review time-resolved laser techniques used to probe the charge carrier dynamics of these heterostructures. Dynamic studies have provided insight into the mechanisms responsible for the improved PEC performance in these materials and helped to guide continued design of α-Fe2O3 heterostructures for further enhancement of PEC water splitting. As summarized in this review article, rational heterostructure design is a promising strategy to push forward the application of α-Fe2O3 for potential low cost and high efficiency solar hydrogen conversion. A better fundamental understanding of the charge carrier dynamics in these structures in turn helps to guide and improve the heterostructure design.

Hematite heterostructures for photoelectrochemical water splitting: rational materials design and charge carrier dynamics

Solid Lipid Nanoparticles (SLN) and Nanostructured Lipid Carriers (NLC) for pulmonary application: A review of the state of the art

Knowledge and foundational understanding of phenomena associated with the behavior of materials at the nanoscale is one of the key scientific challenges toward a sustainable energy future. Size reduction from bulk to the nanoscale leads to a variety of exciting and anomalous phenomena due to enhanced surface-to-volume ratio, reduced transport length, and tunable nanointerfaces. Nanostructured metal hydrides are an important class of materials with significant potential for energy storage applications. Hydrogen storage in nanoscale metal hydrides has been recognized as a potentially transformative technology, and the field is now growing steadily due to the ability to tune the material properties more independently and drastically compared to those of their bulk counterparts. The numerous advantages of nanostructured metal hydrides compared to bulk include improved reversibility, altered heats of hydrogen absorption/desorption, nanointerfacial reaction pathways with faster rates, and new surface states cap...

Nanostructured Metal Hydrides for Hydrogen Storage.

Integrated absorber/electrocatalyst schemes are increasingly adopted in the design of photoelectrodes for photoelectrochemical cells because they can take advantage of separately optimized components. Such schemes also lead to the emergence of novel challenges, among which parasitic light absorption and the nature of the absorber/catalyst junction features prominently. By taking advantage of the versatility of pulsed-laser deposition technique, we fabricated a porous iron(III) oxide nanoparticle-assembled coating that is both transparent to visible light and active as an electrocatalyst for water oxidation. Compared to a compact morphology, the porous catalyst used to functionalize crystalline hematite photoanodes exhibits a superior photoresponse, resulting in a drastic lowering of the photocurrent overpotential (about 200 mV) and a concomitant 5-fold increase in photocurrents at 1.23 V versus reversible hydrogen electrode. Photoelectrochemical impedance spectroscopy indicated a large increase in trapped...

Porous versus Compact Nanosized Fe(III)-Based Water Oxidation Catalyst for Photoanodes Functionalization

Synthesis of mesoporous ITO/TiO2 electrodes for optoelectronics

We have shown that reduction of deuterium permeation through AISI 316L stainless steel can be obtained by the deposition of an (Al,Ti)N coating: a 1.7-μm-thick coating was able to reduce the deuterium permeation flux by a factor 100–1000 in the 473–873 K temperature range. This result is related to the very low diffusivity of the deuterium migrating species in the nitride: in the examined temperature range the evaluated values of the deuterium diffusion coefficient are on the order of 10−12–10−11 cm2/s with an activation energy as low as 0.37±0.03 eV: this activation energy may be related to the defect microstructure of the sample. The (Al,Ti)N layer, which is produced on an industrial scale as an anticorrosive and wear resistant coating, has shown good properties as an oxidation barrier during thermal treatment in air at temperatures up to 873 K.

High temperature efficient deuterium permeation and oxidation (Al,Ti)N barriers deposited on stainless steel

Pulsed laser deposition of nickel oxide films with improved optical properties to functionalize solar light absorbing photoanodes and very low overpotential for water oxidation catalysis

We present a fabrication protocol combining radio frequency sputtering technique and CO2 laser annealing for GeO2 based planar optical waveguides. The effects of pulsed CO2 laser irradiation on the optical and structural properties of pure GeO2 planar waveguide are evaluated by different techniques as m-line and micro-Raman spectroscopy and AFM measurements. Amorphous GeO2 planar waveguide was fabricated by Radio Frequency magnetron sputtering system on v-SiO2 substrate. An increase of the refractive index of approximately 0.04 at 1.5 μm and a decreasing of the attenuation coefficient from 0.9 to 0.5 dB/cm at 1.5 μm have been observed after pulsed CO2 laser annealing. Raman spectroscopy and AFM results showed that after an adapted pulsed CO2 laser annealing, the resulting materials showed a crystalline environment in which the phase of the crystalline GeO2 varies with varying irradiation time.

http://iopscience.iop.org/article/10.1088/1757-899X/73/1/012006/pdf

Nicola Bazzanella

Papers

Porous versus Compact Nanosized Fe(III)-Based Water Oxidation Catalyst for Photoanodes Functionalization

Synthesis of mesoporous ITO/TiO2 electrodes for optoelectronics

High temperature efficient deuterium permeation and oxidation (Al,Ti)N barriers deposited on stainless steel

Pulsed laser deposition of nickel oxide films with improved optical properties to functionalize solar light absorbing photoanodes and very low overpotential for water oxidation catalysis

CO2 Laser irradiation of GeO2 planar waveguide fabricated by rf-sputtering