Porous silicon (Psi) and nanocellulose (NC) hydrogels are nanostructured materials with several properties that make them promising for drug delivery applications. In this work, Î2-carotene (BC) and clofazimine (CFZ) are used as model molecules to investigate the physical and chemical processes governing the interactions of hydrophobic molecules with both inorganic (Psi) and organic (NC) nanostructured carriers. Despite the large number of advantages, Psi does not perform well as carrier for BC, since it stimulates the molecule degradation even if its surface is carefully passivated. Furthermore, during the release experiments, BC tends to nucleate on Psi surface forming aggregates whose dissolution is much slower than the BC molecules release, thus they negatively impact on the control over the drug release. On the other hand NC hydrogels do not pose heavy issues to the release of lipophilic drugs, provided that a suitable surfactant (either Tween-20 or Tween-80) mediates the molecule solvation and its subsequent release into aqueous media. Moreover, NC gels protect BC from degradation much better than its storage in freezer or in organic solvent, making these carriers interesting for DD.

This thesis reports on the results of the so-called free-fall experiment performed on LISA Pathfinder (LPF). After an introduction to the measurement of space-time curvature from space and its application to gravitational wave observation, overviews of LISA and the precursor mission, LISA Pathfinder, are described. Then a specific source of noise arising on LPF, the actuation noise, is investigated, also with reference to the free-fall experiment. Then, the physics and the design of the experiment are described as well as the analysis technique adopted to analyze the free-fall data. Finally, the results of the free-fall data campaign are shown, with a discussion regarding the possible implications for LISA and space-based gravity gradiometers.

My work was carried out with the aim of devising and characterize novel integrated devices for signal routing in optical networks on chip. Several type of optical microresonators, both in a single and coupled configuration (CROW, SCISSOR), are discussed starting from the fundamental theory till dealing with novel configurations. The coupling between a Mach-Zehnder interferometer and such configuration of microresonators is also investigated. Since the used material platform is the silicon on insulator (SOI), an in depth study of the microresonators behaviour has demanded an investigation in both in the linear and non-linear regime. All devices were fabricated through a standard CMOS facility by using deep UV lithography in order to verify the reliability of resolution and throughput similar to those required for commercial applications. Particular attention has been paid in the study of structures robust with respect to manufacturing defects. All the steps necessary to develop a device for integrated optics are studied in deep: device conception, device simulations through analytic and FEM simulations, GDS mask design, experimental characterizations. All the devices parameters are carefully reported to allow the reproduction of the experimental results. Where it was possible, suggestions on how to improve the fabricated devices performance were given.

In the present thesis work, we have developed two different experimental setups for the optical detection of the OH radical in discharges at atmospheric pressure. The first one allows us to improve the time-resolved broad-band absorption spectroscopy. The main advances of the new set up are a better collimation of the UV light and a novel gating scheme. They both significantly reduce the interference of the plasma-induced emission on the absorption measurement. The second setup is dedicated to an improved laser induced fluorescence experiment, which takes advantage of a novel multi-transition excitation scheme. This permits the simultaneous measurements of both the OH density and its ground state rotational temperature. In addition, we have developed a new rate-equation model to rationalize LIF spectra, by taking into account the electronic quenching, the vibrational and rotational energy transfers, and the spatial profile of the laser beam. Finally, the electrical power dissipated in the discharge was accurately measured.

The thesis is divided into two topics: silicon nanocrystals based light emitting devices and erbium doped silicon nanocrystals devices. I have studied silicon nanocrystals based devices. Here I have demonstrated the role of the different injection mechanisms in determining the efficiency of the device. I have studied single and multilayer structures, both in diode or transistor configurations. Lastly, the time dependence of the electroluminescence has been studied, clarifying the role of bipolar or unipolar injection in these structures. On the second part of my thesis, I have studied Er and silicon nanocrystals co-doped devices. Firstly, the study was aimed at the understanding of the efficiency of the electrical pumping of Er ions. Then, integrated optical cavities were designed and fabricated and their optoelectronic properties measured. Here I built a specific set-up in order to measure at the same time the optical and electronic properties of active devices on wafer. Unfortunately, the measurements demonstrated that many nonlinear loss mechanisms set in when the devices are heavily injected with current. Therefore, despite the optical cavities are of high qualities, the system did not show any laser emission. On the other hand, I have demonstrated a fully integrated system where the Er doped injection device pumps a waveguide and the emission is then extracted through a grating. Last result was the experimental verification of the existence of intermediate band states through which the silicon nanocrystals to Er energy transfer occurs.

The contents of the present thesis can be divided into three parts. The first three chapters introduce the general context in which this work was developed: the social impact, the motivations and the key concepts of our research field. In particular, in Chapter 1 we discuss about the energy issue, focusing on the problem of sustainability of the energy sources. Through an analysis of updated energy and population statistics, we come to the conclusion that solar energy is the most environmentally, economically and socially sustainable energy source. Then, in Chapter 2 we present the basics of photoelectrochemical water splitting, as a possible strategy of solar hydrogen production. This discussion is inserted in the more general topic of artificial photosynthesis toward solar fuel generation. In view of the experimental work presented in this thesis, we put attention on semiconductor-based photoelectrochemical water splitting and on heterogeneous catalysis with inorganic catalytic materials. More specifically, we propose physical vapor deposition techniques as synthetic methods suitable for the industrial production of thin films for photoelectrochemical applications. In Chapter 3 we introduce the fundamentals of physical vapor deposition techniques (namely, radiofrequency magnetron sputtering, electron-beam deposition and pulsed laser deposition). The second part highlights some fundamental mechanisms that are relevant in the pulsed laser ablation of metals. In particular, we review our recent results on the modeling of liquid nanodroplet formation in the nanosecond laser ablation of pure metals. Chapter 4 develops a simplified model of phase explosion, based on the theory of homogeneous boiling. Through a continuum approach, we describe the liquid nanoparticle formation in a metastable liquid metal, whose temperature is constant over time and space. The results of our computational simulations are presented here for a set of seven metals (Al, Fe, Co, Ni, Cu, Ag and Au), commonly used in pulsed laser deposition. Our modeling was further improved, taking into account a more realistic spatial and temporal dependence of the temperature. In Chapter 5 we design a simulation of the nanosecond laser ablation of aluminum, which considers phase explosion and vaporization mechanisms. A nanosecond Gaussian-shaped laser pulse was assumed and the spatial gradient of the temperature was calculated according to the heat conduction equation. In this way, space–time resolved homogeneous boiling was studied and the size distribution of the produced liquid nanodroplets is presented. After this long digression on the fundamentals of laser ablation mechanisms, we return to focus on the application of physical vapor deposition techniques to the synthesis of solid-state thin layers for photoelectrochemical water splitting. This third part is composed of three chapters, each one dealing with a different physical vapor deposition technique. Chapter 6 presents the synthesis and characterization of tin-doped hematite through radiofrequency magnetron sputtering. That study allowed us to shed some light on the effect of tin doping on the structural, optical and electrochemical properties of hematite. Indeed, tin-doped hematite was studied as a photoanodic material in some considerable experimental works, but the employed techniques made difficult to decouple the effect of the dopant from other structural and morphological features. Chapters 7 and 8 present the results of our work on the pulsed laser deposition and electron-beam deposition of water oxidation catalysts, respectively. In particular, Chapter 7 proposes the synthesis of a porous amorphous iron oxide catalyst employed to functionalize hematite photoanodes. The small-scale nanostructuring obtained through pulsed laser deposition allowed minimizing some issues such as the parasitic light absorption. In Chapter 8 we characterize pure and binary metal oxide thin films based on Fe, Co and Ni, deposited through electron-beam deposition. In our investigation of the electrocatalytic performance of these water oxidation catalysts, NiFe2Ox results as the most active material, in agreement with recent literature.

Random numbers are fundamental elements in different fields of science and technology such as computer simulation like Monte Carlo-method simulation, statistical sampling, cryptography, games and gambling, and other areas where unpredictable results are necessary. Random number generators (RNG) are generally classified as “pseudo”-random number generators (PRNG) and "truly" random number generators (TRNG). Pseudo random numbers are generated by computer algorithms with a (random) seed and a specific formula. The random numbers produced in this way (with a small degree of unpredictability) are good enough for some applications such as computer simulation. However, for some other applications like cryptography they are not completely reliable. When the seed is revealed, the entire sequence of numbers can be produced. The periodicity is also an undesirable property of PRNGs that can be disregarded for most practical purposes if the sequence recurs after a very long period. However, the predictability still remains a tremendous disadvantage of this type of generators. Truly random numbers, on the other hand, can be generated through physical sources of randomness like flipping a coin. However, the approaches exploiting classical motion and classical physics to generate random numbers possess a deterministic nature that is transferred to the generated random numbers. The best solution is to benefit from the assets of indeterminacy and randomness in quantum physics. Based on the quantum theory, the properties of a particle cannot be determined with arbitrary precision until a measurement is carried out. The result of a measurement, therefore, remains unpredictable and random. Optical phenomena including photons as the quanta of light have various random, non-deterministic properties. These properties include the polarization of the photons, the exact number of photons impinging a detector and the photon arrival times. Such intrinsically random properties can be exploited to generate truly random numbers. Silicon (Si) is considered as an interesting material in integrated optics. Microelectronic chips made from Si are cheap and easy to mass-fabricate, and can be densely integrated. Si integrated optical chips, that can generate, modulate, process and detect light signals, exploit the benefits of Si while also being fully compatible with electronic. Since many electronic components can be integrated into a single chip, Si is an ideal candidate for the production of small, powerful devices. By complementary metal-oxide-semiconductor (CMOS) technology, the fabrication of compact and mass manufacturable devices with integrated components on the Si platform is achievable. In this thesis we aim to model, study and fabricate a compact photonic quantum random number generator (QRNG) on the Si platform that is able to generate high quality, "truly" random numbers. The proposed QRNG is based on a Si light source (LED) coupled with a Si single photon avalanche diode (SPAD) or an array of SPADs which is called Si photomultiplier (SiPM). Various implementations of QRNG have been developed reaching an ultimate geometry where both the source and the SPAD are integrated on the same chip and fabricated by the same process. This activity was performed within the project SiQuro—on Si chip quantum optics for quantum computing and secure communications—which aims to bring the quantum world into integrated photonics. By using the same successful paradigm of microelectronics—the study and design of very small electronic devices typically made from semiconductor materials—, the vision is to have low cost and mass manufacturable integrated quantum photonic circuits for a variety of different applications in quantum computing, measure, sensing, secure communications and services. The Si platform permits, in a natural way, the integration of quantum photonics with electronics. Two methodologies are presented to generate random numbers: one is based on photon counting measurements and another one is based on photon arrival time measurements. The latter is robust, masks all the drawbacks of afterpulsing, dead time and jitter of the Si SPAD and is effectively insensitive to ageing of the LED and to its emission drifts related to temperature variations. The raw data pass all the statistical tests in national institute of standards and technology (NIST) tests suite and TestU01 Alphabit battery without a post processing algorithm. The maximum demonstrated bit rate is 1.68 Mbps with the efficiency of 4-bits per detected photon. In order to realize a small, portable QRNG, we have produced a compact configuration consisting of a Si nanocrystals (Si-NCs) LED and a SiPM. All the statistical test in the NIST tests suite pass for the raw data with the maximum bit rate of 0.5 Mbps. We also prepared and studied a compact chip consisting of a Si-NCs LED and an array of detectors. An integrated chip, composed of Si p+/n junction working in avalanche region and a Si SPAD, was produced as well. High quality random numbers are produced through our robust methodology at the highest speed of 100 kcps. Integration of the source of entropy and the detector on a single chip is an efficient way to produce a compact RNG. A small RNG is an essential element to guarantee the security of our everyday life. It can be readily implemented into electronic devices for data encryption. The idea of "utmost security" would no longer be limited to particular organs owning sensitive information. It would be accessible to every one in everyday life.

Proton therapy is a recent type of radiotherapy that uses high-energy proton beams, and more recently carbon ion beams, to benefit of their physical selectivity. The energy deposited by these particle beams is inversely proportional to their velocity. Therefore they release most of the energy at the end of their path into the tissue. The energy is deposited in a few millimeters, in a zone called the Bragg peak. Before and after the Bragg peak the energy deposition is minimal. The depth and the width of the Bragg peak depends on the beam energy and on the density of tissues located along the beam path. By setting the beam energy, the Bragg peak can be positioned in the tumor site, avoiding the healthy tissues. Because of the sharpness of the Bragg peak zone, proton therapy is advantageous for tumors located near to important body part, such as the brain, spine, and neck. The drawback is that small uncertainties on particle range can have a serious impact on treatment and limit the efficiency of the proton therapy. To obtain more effective treatments in proton therapy real-time range verifications are necessary to perform on-line corrections of the delivered treatment. Among different techniques presented in the literature, positron emission tomography (PET) and prompt gamma imaging (PGI) are the most promising methods for in vivo range verification. PET and PGI are indirect approaches to measure protons penetration depth inside patients because they aim to detect secondary particles resulting from the interaction between proton beams and tissue nuclei. PET imaging detects coincidence gamma rays due to the production of positron emitters and requires some minutes to achieve enough statistics to have a sufficient signal to noise ratio. PGI instead uses prompt gamma rays generated by de-excitation of target nuclei; the quantity of these rays and their temporal emission (few nanoseconds) allow to perform a range verification during treatment with the PGI. Several research groups are evaluating different approaches to realize a prompt gamma imaging system suitable for the use in clinical condition and the optimization of a gamma-ray detector for PGI is still ongoing. The Gammarad project works in this direction and aims to develop an high-performance and solid-state gamma ray detection module (GDM) with a slit camera design. The project is based on a collaboration among Fondazione Bruno Kessler (FBK, Trento, Italy), Politecnico di Milano (Milano, Italy), the Trento Institute for Fundamental Physics and Applications (TIFPA, Trento, Italy ), and the Proton Therapy Center of Trento (Italy). The project is divided into two parts. The first part focuses on the technological development of a gamma-ray imaging module. This module is composed by a gamma-ray detector, based on a solid-state silicon sensor, and an integrated circuit. They are assembled into a compact module with data and control systems. The second part of the project will be dedicated to the experimental validation of the system both in laboratory with radioactive sources and in a real environment, that of proton therapy. The most innovative part of the gamma-ray detector developed for the project is the photo-sensor used for the scintillation light readout. In traditional applications it is a photomultiplier tube (PMT). However, in recent years, Silicon Photomultiplier (SiPM) has become increasingly popular in a variety of applications for its promising characteristics. Among them, current-generation SiPMs offer high gain, high Photon Detection Efficiency (PDE), excellent timing performance, high count-rate capability and good radiation hardness. Due to these characteristics they are used as PMTs replacement in several applications, such as in nuclear medicine (PET), in high-energy physics (calorimeters), astrophysics (Cherenkov telescopes) and in others single-photon or few-photon applications. For its characteristics, the SiPM is also very promising for the scintillator readout in prompt gamma imaging and in high energy gamma-ray spectroscopy. Detectors for these applications must be compact, robust, and insensitive to the magnetic field. They have to provide high performance in terms of spatial, temporal, and energy resolution. SiPMs can satisfy all these requirements but typically they have been used with relatively low energy gamma rays and low photon flux, so manufacturers have optimized them for these conditions. Because of the limited number of micro-cells in a standard SiPM, 625 cells/mm^2 with 40 μm cells, the detector response is non-linear in high energies condition. Increasing the cell density is extremely important to improve the linearity of the SiPM and to avoid the compression of the energy spectrum at high energies, which worsens the energy resolution and makes difficult the calibration of the detector. On the other hand, small cells provide a lower Photon Detection Efficiency (PDE) because of the lower Fill Factor (FF) and as a consequence a lower energy resolution. Summarizing, the energy resolution at high energies is a trade-off between the excess noise factor (ENF) caused by the non-linearity of the SiPM and the PDE of the detector. Moreover, the small cell size provides an ultra-fast recovery time, in the order of a few of nanosecond for the smallest cells. A short recovery time together with a fast scintillator such a LYSO, reduces pile-up in high-rate applications, such as PGI. Based on the above considerations, the aim of this thesis is to develop an optimized gamma-ray detector composed of SiPMs for high-dynamic-range application, such as the scintillation light readout in prompt gamma imaging and in high-energy gamma-ray spectroscopy. SiPMs evaluated for the detector are High-Density (HD) and Ultra-High-Density (UHD) SiPM technologies recently produced at Fondazione Bruno Kessler (FBK). Instead of standard SiPMs, HD and UHD SiPMs have a very small micro-cell pitch, from 30 μm down to 5 μm with a cell density from 1600 cells/mm^2 to 46190 cells/mm^2, respectively. HD SiPMs are produced using a lithography technology with smaller critical dimensions and designed with trenches among SPADs. Small cells have a lower gain which helps to reduce correlated noise, such as After-Pulse and Cross-Talk. Trenches provide an optical and electrical cell isolation, and a smaller dead border around cells which increase the FF limiting PDE losses. UHD SiPMs push the limits of the HD technology even further, by reducing all the feature sizes, such as contacts, resistors and border region around cells. UHD SiPMs have hexagonal cells in a honeycomb configuration which generate a circular active area and a dead border around cells lower than 1 μm. The reduction of this dead boarder can improve the FF in smaller cells although it usually decrease with cell sizes. It is necessary understand how these significant layout changes affect the optical properties of SiPMs to evaluate which SiPM technology provides best performance in high-energy gamma-ray applications. In the first part of the thesis, I presents the characterization of HD and UHD SiPM technologies in terms of PDE, gain, Dark Count Rate, and correlated noise for the cell sizes between 30 and 7.5 μm. The most important markers of SiPMs performance in gamma-ray spectroscopy are however the energy resolution and the linearity when coupled to the scintillator for the detection of high-energy gamma-rays. A typical characterization of the energy resolution of SiPMs, coupled to scintillator crystals, is performed with radioactive source up to 1.5 MeV. However, PGI features gamma ray-energies up to 15 MeV which are not easily provided by the usual laboratory calibration sources. Extrapolating the behaviour of the detector from the "low" energy data is not correct and leads to unreliable data for calibration and performance estimation. Therefore, I developed a novel setup that simulates the LYSO light emission in response to gamma photons up to 30 MeV. A LED (emitting at 420 nm) is driven by a pulse generator, emulating the light emitted by a LYSO scintillator when excited by gamma rays. The pulse generator parameters (amplitude, duration, rise and fall time constants) are adjusted so that the LED emitted photons match the intensity and time distribution of the LYSO emission. The photon number in each light pulse is calibrated from the measurements at 511 keV obtained with a ^(22)Na source and a LYSO crystal coupled to the SiPMs. Using this LED setup I characterized the energy resolution and non-linearity of HD and UHD SiPMs in high-energy gamma-ray conditions. The second part of the thesis provides a detailed description of the scintillator setup and of the setup for the simulation of high-energy gamma-ray response, followed by the results of the characterization performing with these setups. Summarizing the results, the lowest non-linearity is provided by the technology with highest cell density, the RGB-UHD. For the 10 and 12.5 μm-cells we obtained values of 4.5% and 5% respectively at 5 MeV and 6 V over-voltage. On the other hand, we measured the best energy resolution of 2.6% and 2.3% at 5 MeV for the largest SiPM cells of 20 and 25 μm respectively, without the intrinsic term of the scintillator crystal and at 6 V over-voltage. This is due to the dependence of the energy resolution on the photon detection efficiency, which increases with the size of the SiPM cell. The optimal performance of the detector in high-dynamic-range applications, which depends on the several SiPM parameters, such as excess noise factor, photon detection efficiency, and cell sizes of the SiPM, is a trade off between non-linearity and energy resolution. At 5 MeV, the best trade-off for prompt gamma imaging application is reached by the 15 μm-cell. At 10 MeV the 12.5 μm-cell provides the best trade-off, because of the higher number of photons emitted by the scintillator. Furthermore, I distinguish the different components of the energy resolution (intrinsic, statistical, detector and electronic noise) as a function of cell sizes, over-voltage and energy, thanks to the combination of the scintillator and LED setups. The estimation of the intrinsic contribution of the scintillator crystal, coupled to the HD SiPMs, getting consistent results among the several cell sizes. On the basis of previous characterization, HD SiPMs with dimensions of 4x4 mm^2 and 15 μm-cell were chosen to produce the photo-detector module of the gamma camera, optimized for an energy range between 2 and 8 MeV. This module is a 8x8 array of SiPMs which is called tile. The production of the tile requires research on packaging techniques to solve two main challenges: the maximization of the photo-sensitive area and the application of a protective resin, transparent in the near UV to maximize light collection from the LYSO. After some R&D on packaging, I obtained a fully functional tile with 64 SiPMs with a fill factor, ratio between the photo-sensitive area and the total area, of about 86%. This fill factor is comparable to the values obtained when a Through Silicon Vias (TSVs) technique is used to connect SiPMs but without the high production cost and the additional fabrication process complexity of the TSV. It should be highlighted that packaging operations is very critical because it is necessary to produce a tile with all working SiPMs, since defective items can not be replaced in the tile. The last part of the thesis presents the packaging procedure that I have defined to produce photo-detector modules and the characterization of the photo-detector array in terms of energy resolution, position sensitive and non-linearity. The measurements on the tile were carried out jointly with the Gammarad partner of Politecnico di Milano, which provided the ASIC and DAQ for the readout. In conclusion, the R&D activity carried out during this thesis has provided to Gammarad project the final photo-detection module with state of the art performance for high-energy gamma-ray spectroscopy. The characterization of the module shows also a position sensitivity that matches with the SiPM dimensions, and a proper acquisition of high-energy gamma-ray events from 800 keV to 13 MeV. This module will be tested on beam in an experimental treatment room at the Proton therapy facility in Trento by the Gammarad project partners.

The laser, whose name stands for Light Amplification by Stimulated Emission of Radiation, in less than a century has became a fundamental tool in several applications and technological processes, such as metrology, telecommunications, medicine and industry, because of their peculiar properties. More in details, they are spatially and temporally coherent, they exhibit a low divergence and can offer high power density and monochromaticity. The work of this thesis can be placed within the framework of laser assisted industrial processes. Material processing exploits the interaction between a high power laser beam and the matter. The interaction happens in the surface of the material where the extreme heat transferred by the laser source can cause a local phase change, without affecting in a significant way the bulk properties of the treated medium. Typically high brightness laser sources are used. The most used solution is represented by fiber lasers. In the last years the research moved towards the semiconductor laser sources because of the numerous advantages that they o↵er with respects to the other types of sources, like a higher conversion efficiency, a smaller size and the possibility of a mass production. Nevertheless, the maximum output power that can be extracted from a single diode laser is relatively small. The adopted strategies for power scaling rely on beam combining. Here we propose a novel architecture for the implementation of passive coherent beam combining, into a single resonant cavity. The main block of the scheme is an Interferometric Semiconductor Amplifier (ISA). In an ISA, the optical amplifier is placed in one arm of a Mach-Zehnder Interferometer. A sequence of ISA, placed into a common resonant cavity, is used for the power scaling. The theoretical model is presented, and the experimental results are discussed.

My research in these three years has been mainly focused on the characterization of structural and optical properties of three kinds of Si-based materials and devices. The first one is the study of SiOC thin films, carried within the TMR-POLYCERNET project financed by the European community. The scientific objective of this project is to create molecularly-tailored, nanostructured SiOC ceramics with unusual multifunctional properties, including photoluminescence. In addition these novel, polymer-derived ceramics, or PDCs, will have high resistance to oxidation, degradation, corrosion and deformation at temperatures above 1400°C. The aim of our work is focused on the optical characterization of PDCs. The PDCs are constituted from polymeric precursors which can be tailored and designed at the molecular level. These multifunctional properties are then carried over into the ceramic phase by self-assembly and controlled pyrolysis. Thus, these novel materials are apparently polymer-like in their structure (for example, they are seemingly amorphous but contain nanodomains) but have the chemical, mechanical and functional properties of high temperature ceramics. The photoluminescence will be the most important property that will be studied and optimized. The specific objective of this work is to optimize chemistry and processing to achieve bright emission and high external quantum efficiency in high-quality thin film. In the second chapter of the thesis, starting from a brief description of SiOC glasses and the sol-gel process to introduce our work, we explained how the thin films were prepared and characterised. A study on the absorption coefficient of the films is reported, in order to compare it with results in literature of similar samples. The major part of this chapter was focalized on our work on the photoluminescence of the films. At high annealing temperature, we observed a very high yellow luminescence from the films, most notably due to the presence of SiC nanoclusters and C clusters in our samples. A well detailed discussion on the origin of the strong emission is reported. A study of the effects of Boron addition on the photoluminescence of our thin films was also effectuated and by comparing the evolution of the B-free (SiOC) and B-containing samples (SiBOC), the important role of boron in promoting the evolution of nanostructure in our thin films is described. Finally, to have an idea of the potential of our films, their external quantum efficiency (E.Q.E.) was measured. A detailed description of the measurement technique is reported and the results are compared with Si-nc samples whose EQE is well-known. Very high EQE were found for TH films pyrolysed at 1200 °C (11.5 %) and THDH2 films pyrolysed at 1200 °C (5%). These external quantum efficiency values are very promising and make SiOC a very interesting material for LED applications. Another part of the work was devoted to the study of Si-based waveguides, and more particularly Silicon on Insulator (SOI) waveguides and Slot SOI waveguides. This work was carried out within the European project PHOLOGIC. The general objective of the PHOLOGIC project is to explore the mass-manufacturing feasibility of Silicon Nanocrystals inside SiO2 matrix in terms of CMOS technology compatibility for a highly scalable photonic logic gate structure. A XOR gate was chosen as functional validation device. The third and fourth chapters of this thesis are dedicated to this work. In the third chapter, we characterized various building blocks like splitters, MMI and bends made in Silicon on Insulator technology. The loss figures found for these building blocks were useful as a benchmark for further development of silicon microphotonics components and circuits on SOI platform like photonic crystals and ring resonators. In effect, the results of this chapter are basic to the development of the SCISSOR structures based on SOI technology, described in chapter five. In the fourth chapter, we studied nano-Si slot waveguides. Horizontal slot waveguides filled with Si-nc have been realized and characterized in terms of propagation losses as a function of the layer deposition conditions (i.e. Si excess and annealing temperature). We were able to reach propagation losses as low as 3 dB/cm which is the best result reported so far for slot waveguides of very small width (50 nm). We presented also experimental results of resonant optical cavities such single and double ring resonators coupled to the horizontal slot waveguides with very high quality factors. The importance of this works relies on the fact that by optimizing the annealed SRSO (i.e. Si-nc) in the slot, we have significantly reduced the propagation losses and at the same time we can add new functionalities related to the Si-nc optical properties (i.e. light emission and/or non-linear optical effects). Finally, a one-dimensional photonic crystal structure based on horizontal slot waveguide with a photonic band gap around 1.55 μm has also been designed and optically characterized. Finally, the last part of this thesis will be devoted to the characterization of Silicon on Insulators Multi-Resonators. This work is a continuation of the study of SOI building blocks described above, and was carried within the European project WADIMOS. The main goal of the WADIMOS project is to build a complex photonic interconnect layer incorporating multi-channel microsources, microdetectors and different advanced wavelength routing functions directly integrated with electronic driver circuits. Our work in this project is to test innovative optical waveguide division multiplexing circuits based on coupled ring resonators. In the last part of this thesis, we will characterize various coupled ring/disks resonators structures, from simple double coupled rings until eight coupled ring SCISSOR. In the last chapter, we measured and compared the characteristic of the light propagation of different connection geometries for sequences of microrings (or microdisks) resonators. In this work, we studied various configurations of coupled disk/ring resonators. With these various structures, we observed the differences in the transmission spectrum between rings and disks resonators, we noticed the whispering gallery modes and the effect of the gap in the CRIT effect for a serially double-disks resonator. On a first time, we studied the serially coupled configuration CROW where each ring resonator is coupled to one another. For this structure, we restrict our attention to two ring/disk based units. We observed the differences in the transmission spectrum between rings and disks resonators and we noticed the whispering gallery modes and the effect of the gap in the electromagnetically induced transparency effect for a serially double-disks resonator. The second configuration that was studied is the SCISSOR configuration. In this case, all resonators are coupled to both the input and drop port waveguides. We characterized the behaviour of complex eight-resonators SCISSOR devices in the case of microdisks and microrings resonators. In order to facilitate the characterization of these complex structures, a new set-up was also build up, which allowed us to study the scattered light of the resonators from the top as a function of the wavelength. Finally, with this technique, for the first time, we demonstrated the presence of EIT-like band even in complex structures. Extremely small differences between adjacent rings can give rise to the appearance of EIT states, delocalized over only few rings and with a great Q-factor and strong out-of-plane scattering.