Author: Verónica Savignano
(Português) Divulgação de chamada para bolsa PNPD junto ao PPGFSC/UFSC – 2016/1.
SBPMat newsletter. English edition. Year 3, issue 3.
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People in the Materials community: interview with Rodrigo Fernando Bianchi.
In the month when the SBPMat University Chapters program completes two years of existence, we interviewed its coordinator, Professor Rodrigo Fernando Bianchi of the Federal University of Ouro Preto (UFOP), scientific director of SBPMat.
Curious since his childhood to understand the phenomena of nature, Rodrigo Bianchi chose Physics as his undergraduate major, which he studied between 1992 and 1995 in his native city, at the São Carlos Institute of Physics of the University of São Paulo (IFSC-USP). Research opportunities appeared and later he earned a master’s and doctoral degree in the area of Materials, also in the IFSC-USP, under the guidance of Professor Roberto Mendonça Faria. He received his master’s degree in 1997. In 2000, during the doctorate program, he spent six months doing research in United States, at the University of North Carolina at Chapel Hill, (a research stage known as a “doctoral sandwich” program). In 2002, he received the degree of Doctor of Science at IFSC-USP.
During his undergraduate studies, Bianchi complemented his academic activities with tutoring at USP, until he became a teacher at the Electronic Systems Engineering Department in 2004. In 2006, he became a professor in the Physics Department of UFOP. That same year he created the Laboratory of Polymers and Electronic Properties of Materials (LAPPEM). From 2011 to 2013 he was a visiting researcher at the Department of Electrical Engineering and Computer Sciences at the University of California, Berkeley, USA. Between 2013 and 2014, he was the coordinator of the Center for Technological Innovation and Entrepreneurship of UFOP.
Since the creation of LAPPEM, the research and development work carried out by the research group and collaborators of the laboratory have produced scientific papers, patents and enterprises, and have received national-level awards. For example, in 2008, the group was awarded 3rd place in the Werner von Siemens Technology Innovation Award in the “Health” modality and the Incentive Award in Science and Technology for SUS, given by the Ministry of Health for the development of neostickers. Designed for blue light phototherapy to treat neonatal jaundice, the neostickers are organic light-emitting diode sensors that indicate the optimum point of blue light accumulation for the treatment.
Another one, among the several recognitions that took place earlier this year, was a project created by LAPPEM members to introduce to the market a development conducted in the laboratory, which was classified in fourth place among 1.500 startups in Brasil in the ranking “100 Open Startups”. In this case, the product was an adhesive, also based on organic luminescent material, which allows to monitor the level of ultraviolet (UV) radiation absorbed by human skin.
Currently, and since 2014, Rodrigo Bianchi is scientific director of SBPMat. When he took over the direction, he received the assignment to create and lead the SBPMat University Chapters (UCs) program, which currently has eight participating groups based in universities of five Brazilian states. Bianchi is also dean of Planning and Development of UFOP and permanent professor of the postgraduate programs in Materials Engineering and Science: Physics of Materials.
Awarded a level 2 CNPq productivity scholarship, Bianchi is the author of 7 filed patents and more than 40 articles published in international indexed journals. He has supervised 19 master dissertations and six doctoral theses.
The following is an interview with the researcher.
SBPMat Newsletter: – Tell us why you became a scientist and what led you to work in the Materials area.
Rodrigo Bianchi: – I was always a curious child trying to understand the phenomena of nature. This “curiosity” has accompanied me throughout my journey as a scientist, from the basic and secondary cycles, through my studies in Physics in the Institute of Physics of São Carlos, USP, and postgraduate studies in Materials Science and Engineering, also at USP, up to the research lines that I coordinate at UFOP, in polymeric electronic devices applied to healthcare. The research opportunities in polymers I had since my undergraduate years led me to work closer in the applied area. As a result, from Physics I went to Materials Science and Engineering, and today I consider myself a “physicist – materials engineer” with research lines focused on both the fundamental study of charge transport phenomena in organic electronic devices, as well as the idealization of sensors applied to neonatology, to the food area and to the monitoring and control of radiation.
SBPMat Newsletter: – In your assessment, what are the main contributions to the Materials area? Please also tell us of the cases in which you participated to transform scientific knowledge into products.
Rodrigo Bianchi: – Without a doubt I believe that the main contribution was to use the phenomena that made organic electronic devices not feasible for the market, such as photodegradation, that led to low durability and poor performance of organic light emitting diodes (OLEDS), to develop innovative sensors. Something like knowing the principles of operation and limitation of devices that were still in the maturation phase to create new sensors with different applications. An example of this strategy was the use of color change of the OLEDs, generated by the exposure of oxygen and light, which precluded many of the commercial applications of these systems, to develop colorimetric radiation sensing in the form of nanofibers, films and gels. In other words, develop 1, 2 and 3D scale sensors to use in different health areas: from phototherapy control for neonatal jaundice to monitoring UV radiation for sunbathers and construction and rural workers, up to the monitoring of cobalt processes, radiotherapy and food irradiation. So, encouraged by such research, partnerships and guidelines, besides our group in UFOP, there are currently other research groups working in the area in Brazil and abroad. Furthermore, our group is currently composed of physicists, chemists, food engineers, pharmacists and many students and professionals focused on developing multidisciplinary research in the field of organic electronics. The group has generated dozens of articles, patents and guidelines, with a focus to always understand the fundamental phenomena in order to develop innovative organic devices. Due to this characteristic, our team members have been awarded important innovation awards, as for instance by the Ministry of Health, Siemens and the Government of the State of Minas Gerais.
From a technological point of view, the As31 startup, created by students to market these products, was recently in fourth place in the ranking of the 100 Open Brazilian Startups, and regularly meets with major companies to establish B2B partnerships (business-to-business) to launch products into the market. This was the second startup created by members of our research group. The lesson we learned is that there are many difficulties related to creating technological and innovative products. Therefore, the first step to launch a startup involves having a well-trained and competent scientific and technological team. However, having the courage to change and modify the direction of the company is fundamental. For example, today the As31 has two Smart Tags as driving-force products: one to indicate to the consumer possible raw meat contamination processes, caused by temperature variations during its shelf-life, and another to indicate when bathers, especially children, should reapply sunscreen. two applications that emerged from the observation of the problems of OLEDs for more than ten years and which are currently very up to date.
SBPMat Newsletter: – The SBPMat University Chapters (UCs) program, which you have coordinated from the beginning, celebrates its two year anniversary this month. Give us your personal assessment of the results achieved to date and tell us about your plans for the program going forward.
Rodrigo Bianchi: – About the SBPMat UC program, I have to say it has been a great pleasure to participate in this creation and in the work done. It’s a challenge and not an easy task setting up a work routine and the involvement of students who are the future of the materials area in the country. We now have materials groups spread out and concentrated in all regions of the country, from north to south, from east to west. Then, it is very important to unite these students in a single cause, and as a result provide them their value in society. How to do this? Our strategy was to encourage students to form their groups, and this included numerous lectures and disseminations of UCs across the country. Once the UC program were created, most important thing was to encourage students to organize a symposium at the annual SBPMat meeting, in which students had a leading role in society by getting involved in establishing the program and also in organizing the event. An innovation, because I don’t know of any other materials entity that has provided such an opportunity until now. This happened in Rio de Janeiro in 2015 and the involvement and success of the students was clearly seen. These were high-level scientific lectures involving not only materials science themes, but also ethics and scientific writing, for example. In other words, themes that interest directly the students, who are the future of the Materials area in the country. For the next meeting in Campinas, the students are organized to again coordinate this symposium. Regarding the future? The answer is to encourage the formation of new groups, interaction among students and consolidate the participation of everybody in SBPMat.
SBPMat Newsletter: – We always ask the person interviewed in this section of the newsletter to leave a message for those who are beginning their scientific careers. Would you like to say something in particular to these future scientists / junior scientists?
Rodrigo Bianchi: – As a final message to the readers, especially the younger ones: “the Materials area is extremely rich and gives us the opportunity to interact with various themes and professionals from many fields of knowledge. So, enjoy this significant feature. Get involved with competent and motivating people, and have the courage to innovate and bring your ideas into the market. Brazil needs this and you can make a difference!”
Special feature: Sirius, the latest generation Brazilian Synchrotron.
Before the end of this decade, the Brazilian Synchrotron Light Laboratory (LNLS), located in Campinas (SP), will be receiving researchers from Brazil and from the rest of the world to use the Sirius, the fourth generation Brazilian synchrotron that will replace or supplement the UVX – the current second generation Brazilian synchrotron, which has been operating since 1997 and is the only synchrotron in Latin America.
Highly appreciated by the scientific community of Materials Science, and by many other areas, synchrotrons are the best sources of beams of X-rays and ultraviolet light, two very useful types of radiation in the study of matter. The process of producing radiation is achieved by the acceleration of electrons moving near the speed of light and subjected to deviations in its path. When diverted, the electrons lose some of their energy in the form of synchrotron light, which is filtered by monochromators that will release radiation by selectively passing the desired wavelength. Therefore, the X-ray beams or ultraviolet light are carried to the experimental stations or light lines, around the accelerator, which have various scientific instruments. The users of the synchrotron make use of the radiation to analyze its interaction with matter through the scientific instruments to obtain information about the structure and properties of the materials at micro and nanoscale.
Sirius, as its name suggests the brightest star in the night sky, will be able to generate extremely bright light beams (up to a billion times higher than the brightness of UVX) – a very important feature that will allow to perform more and better experiments.
This high-brightness radiation, together with advanced scientific instruments and powerful computers to quickly process large amounts of data, will allow performing a wide range of experiments that will generate scientific and technological results in sectors such as Agriculture, Biology, Geology, Energy and Health, and of course in the Materials Science area.
About 300 people are currently working on the project and construction of Sirius, a large-scale and complex project that involves many challenges. One is the development of the synchrotron light source. As a matter of fact, Sirius is one of the first fourth generation light sources in the world (there is only one more currently under construction in Sweden, but neither one operating). There are many challenges, such as developing a system for the monitoring, diagnosis and correction so that the sensitive electron beam trajectory remains stable. Even the construction of the building itself must meet very specific conditions, in order to ensure an almost complete absence of vibration, however small.
This large-scale Brazilian undertaking, whose value is estimated at 1.3 billion reais, is being conducted by LNLS, which developed the UVX and has taken care of its operation, maintenance and upgrades for 19 years. The general management and direction of the team is under the responsibility of the current director of LNLS, Antonio José Roque da Silva. Full Professor of the University of São Paulo (USP), Roque da Silva has an undergraduate and master’s degree in Physics from Unicamp, and a doctorate (PhD), also in Physics, from the University of California, Berkeley. He is the author of over 120 scientific papers published in indexed journals, many of them related to materials science studies. According to Google Scholar, his publications have over 4,400 citations.
The SBPMat Newsletter interviewed Roque da Silva on the technical characteristics of Sirius, the possibilities it offers to the materials science community, the progress of the project and the future of UVX, among other issues.
SBPMat: Newsletter – Sirius will be a high brightness synchrotron light source. What is the importance of brightness for research in Materials Science and Technology?
Antonio José Roque da Silva: – For a given frequency of radiation, its brightness is directly proportional to the flux (number of photons per unit time) and inversely proportional to the product of the beam size times the beam divergence angle). The latter quantity is the beam emittance. Therefore, the lower the emittance, the higher the brightness.
The high-brightness affects the analysis of the materials in different ways:
a. The higher the brightness of the light produced by the synchrotron, the higher the number of samples that can be analyzed within a time period; This allows performing experiments with temporal resolution, which allows to monitor the progress of reactions or processes, e.g., as a function of time.
b. Higher brightness means a better signal-to-noise ratio of different analysis techniques.
c. Low emittance, hence higher brightness, allows probing smaller spatial scales by analytical techniques. This opens study opportunities using nanometer-sized beams, important in areas such as nanotechnology, and other areas.
d. Higher brightness allows the emergence of new techniques or to explore them more effectively. This occurs, for example, with the Coherent Diffraction Imaging technique. Higher brightness will greatly benefit imaging techniques, tomography and microscopy.
SBPMat Newsletter: – What are the limitations of UVX synchrotron that will be overcome by Sirius? For example, will there be characterization techniques of materials in the experimental stations of Sirius that cannot be installed in UVX?
Antonio José Roque da Silva: – The major difference between the two machines is the energy range in which they operate. The electrons in the storage ring of Sirius will be accelerated up to the energy of 3 GeV, more than double the energy of UVX. This results in producing higher energy X-rays and enables more in depth studies of materials such as steel, concrete and rock due to the penetration of X-rays up to a few centimeters, against some micrometers of the UVX.
Also because of the energy difference, the number of chemicals that may be studied by soft X-ray spectroscopic absorption is also different. In the UVX less than half of the chemicals can be studied, while almost all elements of the Periodic Table can be studied in the Sirius.
The low brightness and high emittance of UVX greatly limits the most modern synchrotron techniques available to the scientific community of the country. Nanotomography, coherent diffraction imaging, fluorescence nanomicroscopy, nanocrystals analysis, materials research under extreme conditions (high pressures and high temperatures), inelastic scattering, temporal monitoring of various processes, together with nanometer spatial resolution and chemical resolution (for example, important for catalytic processes), among many other techniques, cannot be performed in UVX or are carried out with great limitations, however they can all be carried out, with high standard, in the Sirius.
SBPMat Newsletter: – What will happen to the UVX? Will it be dismantled?
Antonio José Roque da Silva: – It should be emphasized that everything that the UVX does today can be done much better in Sirius. In addition to the large number of new experiments that cannot be performed in the UVX, as mentioned earlier. The LNLS has decided that during the commissioning period of the Sirius beamlines, the UVX will be kept operational to ensure that the community is not affected by any discontinuity. However, it is not known if after Sirius becomes fully operational the current machine will be preserved or disabled. We know that the scientific instrument available today in some experimental stations of UVX will be transferred to Sirius. Additionally, the cost and feasibility of maintaining the simultaneous operation of two synchrotron light sources must be assessed, as well as the staff (engineers, technicians, researchers and etc.) needed to operate both sources. It is also necessary to assess the users’ level of demand for the experimental stations of UVX once Sirius is fully operating.
SBPMat Newsletter: – Will the expertise of professionals (scientists, engineers, technicians) and Brazilian companies developed during the construction of UVX be used in Sirius? If yes, in what way?
Antonio José Roque da Silva: – The Sirius project would not be possible without the expertise and skills of the professionals formed by LNLS over the years, particularly during the construction of UVX. This high-capacity and specialized professional body (scientists, engineers, technicians) formed over the past 30 years, is crucial to the success of Sirius. The amalgamation of experienced professionals that originated with the construction of UVX, including the young people, is a key strategy of the LNLS – for Sirius and for the future of the laboratory. From a technical point of view, the knowledge accumulated by our engineers and technicians during the construction and operation of UVX is what allowed to design a state of the art synchrotron such as Sirius. This experience will also be crucial to the operation of the new synchrotron. And the same goes for the scientists. The involvement with the construction and operation of the beamlines and the experimental stations of UVX is an important factor for the projects of the sophisticated beamlines of Sirius. The ongoing involvement of these researchers in training the new users, which is regularly performed by LNLS, is also fundamental, and which dates back to the beginning of the construction of UVX. We highlight that all of this knowledge acquired over the years also depends on a strong interaction with the international community of synchrotrons. The LNLS is strongly inserted in this community.
From a perspective of companies, the number of companies involved in the construction of the UVX was small. The UVX was not only designed by the LNLS but also mostly built within the LNLS. However, some companies which were important partners of UVX, as for instance Termomecânica, are also participating in the construction of Sirius. But LNLS successfully structured specific programs to involve Brazilian companies in the development and construction of various components for Sirius. These programs are in partnership with research funding agencies like FAPESP and FINEP. The development of partnerships with Brazilian companies will also be important for the future. Finally, the knowledge created by the Brazilian companies that cooperated (and that will continue to cooperate) with the project is extremely important and exceeds the limits of the project itself. This is why we consider Sirius to be a “structuring” project, whose developments will be reflected in new technologies, new products and processes that will bring benefits to the Brazilian high-technology supply chain.
SBPMat Newsletter: – Because it is a very complex, high standard and pioneer engineering project, (there is no other operating 4th generation synchrotron in the world), the construction of Sirius has unprecedented challenges, right? As project director, how do you address these challenges?
Antonio José Roque da Silva: – We rely largely on the experience, knowledge and audacity of the team of scientists, engineers and technicians of the LNLS. The courage of this team to face such challenges is among the greatest legacies dating back to the construction of the UVX. The compelling story of the construction of UVX has already been addressed in other SBPMat newsletters [Newsletter Note: see here the first and second part of this story). The culture of “yes, we can do it”, which comes from the beginning of LNLS, it crucial to overcome the challenges. One strategy is to increase the professional personnel, fundamental given the size of Sirius, mixing young people with the more experienced professionals, ensuring to preserve the existing in-house culture and knowledge. In addition to this experience, competence and courage, the continuous interaction with other laboratories is a key factor. We invested heavily in this area, sending LNLS professionals abroad and bringing experts from abroad to visit the laboratory. In this respect, also important is the assessment of our solutions by leading international experts. This is done through evaluation committees that regularly come to LNLS, and through the presentation of our results in conferences and specialized workshops. Also important is the investment made in cutting-edge infrastructure in both manufacturing and metrology. Finally, an important part is in regard to management and coordination of the activities and staff, thereby ensuring the efficient implementation of the necessary processes.
SBPMat Newsletter: – Tell us about the participation of national and international external companies and institutions in CNPEM regarding the development of Sirius.
Antonio José Roque da Silva: – One of the goals of the Sirius project is to stimulate the development of the Brazilian industry, by promoting demands related to technological developments, services, raw materials, processes and equipment. The goal is to apply between 65% and 70% of the project’s funds in the country. We should bear in mind that the project is 100% Brazilian.
Among the already established partnerships, we mention as an example the partnership created with the company Termomecânica of São Paulo, which developed the process to manufacture the raw material for the vacuum chambers of the storage ring and also the hollow copper wires for the electromagnets that allow cooling the water circulating through the pipes (this development dates back to UVX). Another example is the company WEG Indústrias (SC), a traditional electric motors manufacturer, which will manufacture over 1350 electromagnets for Sirius, designed by the technical staff of LNL. This is an exceptional partnership related to the sophisticated development of production processes and which has been extremely successful.
There are also examples of partnerships with smaller companies, such as FCA Brasil (Campinas, SP), for the manufacture of booster vacuum chambers, and with the Company EXA-M Instrumentação do Nordeste (BA), for the development and manufacturing of the devices for heating the vacuum chamber of the storage ring, and with Engecer of São Carlos for the manufacture of special ceramic vacuum chambers.
To increase the participation of national companies in the Sirius project, other systematic initiatives were undertaken. In 2014, negotiations with FINEP and FAPESP culminated in the launching of the first public call to select São Paulo-based companies for the development of 20 technological demands of the Sirius project, with resources of R$ 40 million. These funds were made available under the PIPE/PAPPE grant program, so that each proposal could request up to R$ 1.5 million for its development. Eight companies were selected to develop 13 research projects to carry out the challenges proposed in the bidding process.
In 2015 a second public call for proposals was launched for the development of 13 new technological challenges, with resources amounting to R$ 20 million under the same program. February was the deadline for the submission of bids by the companies, which are currently under analysis by FAPESP. For the second half of 2016 we expect that at least thirteen other companies are approved to develop the challenges of the second FAPESP/Finep call to support the Sirius project.
From an international point of view, as already mentioned, the continuous interaction with several laboratories has been vital to the project. An interesting detail is that today, as we are at the frontier and with several innovative solutions, needless to say there are international groups interested in interacting with the LNLS. That is, Sirius is obviously an important international vector.
SBPMat Newsletter: – What are the funding sources of the project.
Antonio José Roque da Silva: – The project is mainly funded by the Federal Government, through the Ministry of Science, Technology and Innovation, MCTI. It should also be mentioned that the Sirius project was recently included in the Growth Acceleration Program, better known as PAC, and is listed as one of the first MCTI projects to be part of the program.
Other important resources were provided by the State Government of São Paulo. For example, the land area of 150,000 square meters where Sirius will be installed was acquired by the State Government and granted to CNPEM.
Moreover, FAPESP has been an important partner in the interaction programs with companies and in supporting events and in the acquisition of scientific instruments that will be installed in the experimental stations (beamlines) of Sirius.
SBPMat Newsletter: – At what stage is the project now? What is the forecasted inauguration date of the light source and the first experimental stations?
Antonio José Roque da Silva: – The construction work of the Sirius building is about 20% complete. Part of the superstructure of the main building and part of the metal structure of the cover of the main building has already been built. An important milestone is making the tunnel available to begin assembling the accelerators at the end of 2017.
Several components of the accelerator are in the production phase. All quadrupoles and correctors of the booster have already been manufactured (by WEG) and delivered. Last week the pilot-batch of sextupoles was delivered, and the manufacture of the sextupoles will begin in two weeks. The prototypes of the booster dipoles will be delivered by the end of March, and its production should begin in early May. The Linac linear accelerator is ready and undergoing tests at the Shanghai Institute of Physics. Additionally, other components have concluded the development stage and are awaiting approval to start production, such as the vacuum chambers of the booster and part of the vacuum chamber of the storage ring. The RF booster cavities have been ordered, and the RF cavities of the storage ring will be ordered. Several other subsystems are in the final prototyping or in the initial production phase.
With regard to the experimental stations (beamlines), their projects are entering the technical detailing and construction phase and/or components acquisition. The projects of the Ipê, Carnaúba, Ema and Cateretê lines are now entering a detailed components phase of the experimental stations, technical designs and construction/custom component orders, such as inverters and mirrors which have a delivery time of up to two and a half years. Basically all the important beamline prototypes will be completed by the end of 2016. Overall, the chronogram of Sirius is on schedule, and the first beam and initial commissioning phase is expected in 2018, that way in 2019 the machine can receive the first researchers.
SBPMat Newsletter: – Would you like to add any comments or information?
Antonio José Roque da Silva: – It should be highlighted that Sirius is a result of the evolution of both the internal capacity of the laboratory as well as the maturing of the scientific community in Brazil. The concept of an Open National Laboratory, which is the goal of LNLS to provide an extremely sophisticated and unique equipment to the ST&I community is at the heart of the culture in the laboratory. Its high performance operation requires constant investment to train this highly specialized human resources (scientists, engineers, technicians), for the maintenance of cutting-edge equipment and infrastructure (accelerators, beamlines, experimental stations, support groups, metrology, manufacturing techniques, etc.), for user training, for developing new technologies, excellence in communication and management. The synchrotron project in Brazil, from UVX to Sirius, is something that all Brazilians can and should be proud of, bearing in mind it began from “square one” and in thirty years has placed Brazil in the state of the art, with a significant effect on the formation of human resources, high-level science, innovation, high-technology development and internationalization.
Featured paper: Designing structures to manipulate light.
[Paper: Oxide-cladding aluminum nitride photonic crystal slab: Design and investigation of material dispersion and fabrication induced disorder. Melo, EG; Carvalho, DO; Ferlauto, AS; Alvarado, MA; Carreno, MNP; Alayo, MI. Journal of Applied Physics 119, 023107 (2016). DOI: 10.1063/1.4939773.]
Designing structures to manipulate light
Photonic crystals are nanostructures capable of manipulating visible light and other forms of electromagnetic radiation by organizing its structure in periodic patterns.
In addition to the natural materials with these characteristics, such as opal, photonic crystals are man-made and are generally classified as metamaterials. Its characteristics (shape, size and composition) are designed to control light waves. Through nanofabrication processes these become tangible structures and are used in many “nanophotonic” devices. Nevertheless, producing these structures is by no means a simple task.
With a study based on computer simulations, a team of Brazilian scientists headed by researchers from the Polytechnic School of the University of São Paulo (EPUSP) presented scientific contributions that can be used to improve the production of photonic crystals to enhance their performance of manipulating light. According to Emerson Melo, the first author of a paper on the study that was recently published in the prestigious Journal of Applied Physics (JAP) “the work presents a detailed analysis of the effects caused by nanofabrication processes on the optical properties of planar photonic crystals produced on silicon dioxide-cladding aluminum nitride”.
“The idea emerged from the opportunity of combining the excellent optical and physical characteristics of aluminum nitride (AlN), such as transparency over a wide wavelength range (from the near infrared to the ultraviolet range), its non-linear effects, great stability and temperature variations, with the advantages provided by photonic crystals, such as the construction of high-efficiency waveguides, curves and resonant cavities in nanoscale dimensions, in addition to the various optical effects of photonic crystals, such as very low group velocity and low-intensity nonlinear effects of the materials”, adds Emerson, who is a doctoral student in Microelectronics – Photonics in EPUSP, within the Group of New materials and Devices of the Microelectronics Laboratory of the Department of Electronic Systems Engineering. Emerson`s doctoral research, whose advisor is Professor Marco Isaías Alayo Chávez, enquires into the study, production and characterization of nanophotonic devices such as waveguides, resonant cavities, optical modulators and switches in aluminum nitride photonic crystals.
The study that resulted in the paper published in the JAP began with an experimental stage. Thin films of aluminum nitride and silicon dioxide (SiO2) were manufactured by the EPUSP group, and with the research collaboration from UFMG and UNESP they were analyzed by the Variable Angle Spectroscopic Ellipsometry (VASE) technique to determine the dielectric functions, which was later used as the theoretical research data.
Then, the EPUSP group designed a photonic crystal, ideal in terms of performance and manufacturing possibilities, consisting of a layer of aluminum nitride between two silicon dioxide layers, with round holes arranged in a repeating pattern along the “sandwich” material. Using analytical and numerical methods, the USP researchers simulated some of the “side effects” of the photonic crystal manufacturing processes of this type (e.g., variations of size and location of holes) and theoretically analyzed how these imperfections affect the performance of the photonic crystal.
The theoretical research of Emerson and the other researchers of EPUSP focused on the imperfections generated in the two main stages of the nanofabrication process normally used in photonic crystals such as the one studied: electron-beam lithography and plasma-assisted dry etching. “The results presented allow to assess that the electron-beam lithography process has greater effect on the performance of devices that explore the dispersion of electromagnetic radiation through the photonic crystal, such as prisms, optical switches and modulators”, says Emerson. “However, the quality of the dry etching process has a more profound impact on the characteristics of devices into which linear or exact defects are introduced in the periodic network of the photonic crystal to insert harmonic modes within the photonic band gap. In this case, the dry etching has to be extremely well controlled for manufacturing the devices where waveguides and resonant cavities are among its main elements”.
In addition to making headway in understanding the role of nanofabrication processes of photonic crystals in the performance of nanophotonic devices, the authors of the paper were able to define a method to design planar photonic crystals with core and cover in thin film dielectric materials. “The methodology includes determining the dielectric function of the material by the spectroscopic ellipsometry technique to analyze the dispersion effects of the materials, determining the geometrical parameters that maximize the photonic band gap and the analysis of the impacts caused by deviations introduced in the manufacturing process”, explains Emerson.
The research received financial support from the National Council for Scientific and Technological Development (CNPq) and from the Financier of Studies and Projects (Finep).
The authors of the article. From left to right, at the laboratory:.
(Português) Chamada de pré‐qualificação para contração de profissionais para projeto de Inovação Tecnológica.
(Português) XV Brazilian Materials Research Society Meeting: aberta a submissão de trabalhos.
(Português) Oportunidades para pesquisadores no CNPEM.
Postdoctoral positions available for glass research.
Applications for postdoctoral fellowships are invited for conducting fundamental and applied research at the Center for Research, Technology and Education in Vitreous Materials (CeRTEV) in São Carlos, Brazil. The period of the fellowship is two years, starting in August 2016, renewable for two additional years upon mutual consent.
CeRTEV is an 11-year (started in 2013) joint effort of the Federal University at São Carlos (UFSCar), the University of São Paulo (USP) and the State University of São Paulo (UNESP), to conduct research in the area of Functional Glasses and Glass-Ceramics.
The postdoctoral research will be focused on fundamental and/or applied investigation of glass and glass-ceramics. The researcher is expected to conduct the post-doc activities in one of the joint CeRTEV laboratories and supervised by one of our Principal Investigators, but in close collaboration with the other CeRTEV researchers.
Applicants should have a PhD degree in Physics, Chemistry, Materials Science or Engineering, and have a genuine interest in conducting interdisciplinary research in an international environment. Previous experience in glass science, solid state physics or chemistry is advantageous. The monthly fellowships (non-taxable) include ca. R$ 6.800,-plus 15% professional expenses. Travel expenses from and to their home countries will also be covered. The three sister universities are committed to increasing the proportion of women and ethnic minorities in academia.
Please send your application including CV, list of publications, a 2-page research proposal, and the names and email addresses of two references by May 5, 2016 to Prof. Dr. Edgar D. Zanotto (dedz@ufscar.br) and Laurie Leal (laurie_leal@yahoo.com.br).