Scattering evaluation in nanoparticle liquid suspensions using Z-scan-thermal-lens configuration.

George Boudebs

The understanding of nanoparticles scattering is very important, especially for the medical area where the majority of imaging techniques and photothermal therapeutic applications are subject to this phenomenon. Also, distinguishing thermal lens effect from electronic third-order nonlinear response could help to better understand fundamental physics. In this talk, the main characteristics of the thermal lens effect is studied as a time-resolved Z-scan configuration using cw-single Gaussian beam. We will focus on the evaluation of the measurement error from statistical calculations also to check the linearity of the response and the way to extract the thermo-optical characteristics of different absorbing liquids. The results will be applied to demonstrate the feasibility of absorption and scattering efficiencies determination on gold nanoparticles of 5 and 50 nm diameters.

Illuminating materials: The materials science of light emitting diodes

Rachel Oliver

About a quarter of the electricity generated worldwide is used for lighting. Energy efficient light bulbs based on light emitting diodes (LEDs) are about five times more efficient than traditional incandescent bulbs, and hence have the potential to allow enormous energy savings. The key material used in LEDs which emit white light is gallium nitride, a human-made compound, which has never been observed to occur in nature. Optimising this new material to make LEDs which are efficient, long-lived and reasonably affordable has been a huge challenge, and despite the undoubted commercial success of these devices many aspects of their operation remain mysterious. Materials scientists can take LEDs apart, literally atom by atom, to understand their structure and how this controls their properties. The relevant techniques emerged from traditional metallurgy, but are now being used to understand materials for cutting edge optoelectronic devices, illustrating how the basic principles of materials science are vital to the development of the technologies of tomorrow.

The world of optical solitons in ultrafast fiber lasers.

Philippe Grelu

I will provide a short introduction about the milestones that led to the generalized use of fiber lasers, from the research lab to the industry. Then, I will focus on the generation of short and ultrashort pulses from fiber lasers. The fiber cavity medium involves in general a substantial participation of nonlinear and dispersive effects. That is why soliton concepts have always been closely related to mode-locked fiber laser operation. I will show how the goings and comings between experiments and theoretical considerations have made these concepts evolve, toward the generalized notion of a dissipative soliton, which made scientists move beyond conventional laser stereotypes. I will illustrate how the fiber laser platform allows us to experiment vivid signatures of the complex nonlinear dynamics of temporal solitons, such as soliton molecules and complexes, which turn out to manifest some analogies with their matter molecule counterparts.

Integrated photonics in access networks: the challenges.

António Teixeira

In this work we will address the specific field of access networks and FTTH. The particularities of this field and context make all developments more demanding. In one hand the players see the opportunities that this brings, like billions of subscribers eager for bandwidth, and on the other the same see the challenge of the cost/maturity point that each service or interface has to reach in order be able to be mass deployed.

These challenges will be addressed by comparing the existing bulk approaches being partitioned today and how the integrated photonics world is developing its ecosystem and techniques to surpass the challenges.

Understanding the optics of the retina and photoreceptors with ballistic photons

Brian Vohnsen

The photoreceptors of the retina are highly directional in their sensitivity to light. This shows in visual optics via the classical Stiles-Crawford effect of the first kind and in retinal imaging by highly directional backscattering of light. In this contribution we review our work on understanding the optics of the photoreceptors in both healthy eyes and in eyes affected by retinal degenerations combining psychophysical optics measurements with optical imaging and eye modelling. Finally, we discuss how the optics principles may be involved in the process of emmetropization that hinders myopia onset and in detecting the sign of defocus in the process of accommodation and on how the knowledge gained may be used in the development of new ophthalmic lenses.

Exploring spontaneous emission for building up global quantum networks

Daniel Felinto

The quantum internet is emerging as an extension of the protocols for quantum communication, incorporating local processing of information together with distribution of quantum entanglement among multiple sites. Even though quantum communication initially developed with a focus on local networks, in the last years large steps were given in the distribution of quantum entanglement through sattelites, stablishing the first quantum networks of truly global reach. Behind this trajectory of technological development, there has been also conceptual developments in the last decades about the ubiquitous nature of quantum entanglement and its presence in various natural phenomena routinely occurring around us. Here I will discuss this arch of ideas that goes from the observation of quantum entanglement is ever simpler phenomena, up to its control and application in quantum communication of growing distance and complexity. I will focus on the work of our group and in the recent perspectives of integrating this work in the global effort to develop technologies for a quantum internet.

Wideband Amplification for the Next Generation of Optical Transport Networks

Marcionilo José da Silva

The data transmission over optical channels in wideband systems is an important alternative to increase the capacity of the current optical transport networks without a significant increase in implementation and operational costs. However, to allow these systems to achieve long-reach transmissions, the development of appropriate optical amplifiers to provide high gain with low noise insertion in each new optical band to be explored is a crucial step. This work briefly describes the main technological alternatives with suitable performance and complexity for high-capacity optical links in the extended C+L band, including fiber-doped, Raman-based, and semiconductor optical amplifiers. The amplifiers’ characteristics, most common use cases, design and optimization methodology based on Artificial Intelligence techniques, as well implementation and commercial challenges are discussed in this paper.

Metal-Nanostructures for Nonlinear Photonics

Cid Bartolomeu de Araújo

Nonlinear optical experiments with metal-nanoparticles and metal-nanoclusters hosted in liquids and glasses will be reported. The metal-dielectric nanocomposites were produced by selecting the nanostructures compositions, shapes, densities, and spatial arrangements, as well as by choosing appropriate hosts. Optical nonlinearities beyond the third-order were observed and characterized. The stable propagation of spatial-solitons was studied along with the guiding of gaussian light beams using optical vortices. A procedure for optimization of all-optical switches, the upgraded operation of optical amplifiers in the shortwave infrared region (SWIR), the optical modulation based on the dynamic control of gold nanorods driven by an external electric field, and the study of the nonlinear behavior of a metal-metasurface in the SWIR, will be described to illustrate proof-of-principle applications of nanocomposites.

Optical metrology of structures and surfaces

Silvania Pereira

Optical scatterometry is a method that can be used for the characterization of unknown properties of a medium by measuring some parameters or properties of the scattered light, such as its intensity distribution, polarization and coherence. The scattered field is usually detected or observed at a distance of many wavelengths from the medium, in the so called far field region. Far field detection is convenient in terms of data acquisition, but the drawback is that, in the far field, high spatial frequency information contained in the near field is lost. By measuring the scattered far field one does not obtain a direct image, but instead by means of solving an inverse electromagnetic model and taking a priori knowledge into account, one can infer some parameters of interest of the medium/scatterer.

In this talk, we show a particular scatterometry technique, in which a coherent light beam is focused by a lens on a surface to be inspected and the scattered light is collected and detected in the far field. This technique has been successfully used for characterization of nanostructures and contamination detection for the semiconductor industry.

Novel photonic technologies for biosensing at the point of need

Sebastian Wachsmann-Hogiu

Point of need testing has tremendous value in sensing (medical and non-medical) in resource-poor areas. The ideal point-of-need device is a portable ‘sample-in-answer-out’ system, which requires simplicity in operation. However, most sensing technologies require quantitative, diagnostic-level performance, and necessitate specialized instrumentation, limiting their use in point-of-need applications. To adapt biosensors to resource-poor locations, device miniaturization for portability, cost-effectiveness, and easy sample processing needs to be considered while maintaining their efficacy. Consequently, incorporating photonic technologies into biosensing platforms is needed to address this issue. I will present our work on integrating sample handling (the microfluidic component), biosensor chemistry (the assay), and data recording (the reader) into one single device. This approach leverages recent developments in the semiconductor industry where CMOS devices are manufactured at scale for low cost (<$1) and achieve high performance such as improved efficiency in converting photons to electrons (close to 90%) for improved sensitivity, small pixel size (<1 micrometer) leading to high spatial resolution, and large active area (>3x2mm) to accommodate several microfluidic channels.

5G-NR FiWi Systems Based on FSO, VLC, RoF and PoF Towards 6G

Prof. Dr. Arismar Cerqueira Sodré Junior

This seminar is going to concisely and comprehensively covers all-important aspects of diverse 5G optical-wireless communications (OWC), including the fundamentals and state-of-the-art of free space optical (FSO), visible light communication (VLC) and radio over fiber (RoF). Moreover, implementations of 5G New Radio (5G-NR) Fiber/Wireless (FiWi) systems based on FSO, VLC, RoF and power over fiber (PoF) towards the sixth generation of mobile networks (6G) are going to be reported into details. Deployments of 5G-NR FiWi systems operating in the 26 GHz frequency band at dozens of Gb/s throughput, as well as the concept and implementation of machine learning (ML)-based pre- and post-distortion schemes for RoF systems are going to be demonstrated and properly discussed. All OWC experiments have been carried at the Laboratory WOCA (Wireless and Optical Convergent Access) from Inatel in the city of Santa Rita do Sapucaí-MG, Brazil.

Optical and Fiber Optic Sensors – Theory and Applications

Marcelo Martins Werneck

Prepared by a top expert in the field, with many developments, real applications and patents, this lecture will be an invaluable resource for physicists, electronic engineers and will be well accepted by teachers, students, technicians and those working in the sensor area. This lecture discloses the advantages and capabilities of optical fiber sensors in research and industry, including two technologies, the plastic optical fiber (POF) and the silica fiber. Apart from presenting several technologies applying the POF as a sensor, this tutorial will also deal with another kind of technology, the Fiber Bragg Grating (FBG). FBGs can be found in many industrial applications and I will show our experience in applying FBGs in many types of sensors for the electric energy industry.

The tutorial starts with the theory of optical fiber sensors applying both POF and FBG. Then it focuses on several practical uses of sensors including successful field applications designed by our laboratory in areas such as Oil & Gas, Biotechnology and Electrical Energy.

The following topics are presented and discussed throughout the lecture: Optical Fiber Sensors technologies; Temperature Sensing; Strain & Force Sensing; Refractive Index Sensing; High voltage switch monitoring; Current & Voltage Sensing; Gas Sensing; Chemical & Biological Sensing; Oil Leaking Sensing; High voltage and high current measurements; Gas flow velocity measurements.

Status of Luminescence Nanothermometers for Biomedicine

Carlos Jacinto da Silva

In recent years, there has been an increasing interest in luminescent nanoparticles (LNPs) as biocompatible optical probes for diagnostic, therapy and fluorescent probes. Special attention has been given to the use of nanoparticles as luminescent nanothermometers (LNThs) because the temperature is a fundamental parameter in a variety of areas. In biomedicine, for example, the temperature is one of the most critical parameters affecting the dynamics of living specimens due to the strong temperature dependence of cellular dynamics, since abnormal temperatures could induce irreversible effects. Furthermore, small temperature anomalies could indicate many diseases or health dysfunctions such as tumors, inflammation, so on. Therefore, the local temperature monitoring can be used as an effective early detection procedure and for therapy as well. Unfortunately, recent results have raised some concerns about the reliability of “classical LNThs” due to the presence of non-negligible tissue-induced spectral distortions. The scientific community is, in fact, looking for a straightforward solution to this problem that would allow continue to consider LNThs as a reliable and robust technique for intratumoral thermal reading. In this talk, it will be presented in a well-summarized form what has been done on fluorescence and thermal images applied to biological systems.

From machine learning for photonics to photonics for machine learning in fiber-based and integrated devices

Roberto Morandotti

AI and Machine learning (ML) find increasing applications in the field of photonics. On one hand, ML can assist photonics via the use of evolutive algorithms that can be used to optimize the response of a given device or process. As an example, the straight-forward on-chip design of an unbalanced Mach-Zehnder interferometer cascade (UMIC) can be used for either custom- tailoring the spectrum of supercontinuum generation, or to perform efficient pulse shaping in the (tens of) picosecond(s) regime via temporal coherence synthesis. On the other hand, photonics can assist ML. Specifically, artificial neural networks (ANNs) are capable to classify different sets of data and are of significant interest for machine learning tasks such as computer vision, speech recognition, playing board games and medical diagnosis, to name only a few. Optical- based neural networks are especially attractive as they have the capability to dramatically accelerate the computing speed of ANNs and thus overcome the intrinsic bottleneck in bandwidth that currently limits the performance of electronics-based approaches. Furthermore, a specific class of ANNs, namely Convolutional Neural Networks (CNNs), is capable to greatly reduce network complexity without affecting the accuracy of the predictions by a fully connected neuronal network. In this talk, I will give an overview of some of these approaches and will discuss both advantages and limitations.

Combining pulsed lasers and photothermal nanoparticles for delivering functional molecules in living cells and beyond

Kevin Braeckmans

Intracellular delivery of bioactive compounds, such as proteins and nucleic acids, into living cells is a generic requirement for many applications in the life sciences. Although substantial effort has gone into developing viral and non-viral nanocarriers, they each come with their limitations, including safety concerns and limited efficiency. Physical delivery methods offer an interesting alternative solution. Electroporation is a notable example but is often associated with high cell toxicity. Laser technology combined with photothermal nanoparticles has emerged as a promising intracellular delivery method combining high delivery efficiency with flexibility and good cell viability. Cells are first incubated with photothermal nanoparticles which are adsorbed to the cell membrane. Local heating effects upon laser irradiation create pores in the membrane through which compounds in the surrounding cell medium can then enter the cell. Using this so- called ‘photoporation’ technology, we have demonstrated that many cell types can be efficiently transfected, including primary neurons, macrophages and T-cells. Compounds that can be delivered include nucleic acids (siRNA, mRNA, pDNA, …), proteins (e.g. nano- and antibodies), gene editing complexes (e.g. CRISPR/Cas9) and contrast agents (e.g. for MRI). Applications range from fundamental biological investigations to the engineering of therapeutic cells for cell-based therapies. In addition, we have demonstrated that the same principle can be used to disrupt bacterial biofilms or to destroy vision-impairing ‘floaters’ in eyes in vivo. In summary, pulsed lasers and nanoparticles offers the possibility to interfere with biological tissues in a highly controlled manner, thus opening up unique biomedical applications with plenty of room for further exploration and development.