Prof. Mauro Fernandes Pereira obtained his PhD at the Optical Sciences Center, University of Arizona and has given important contributions to Nonequlibrium Greens Functions (NEGF) Many Body Theory of Transport and Optics of Semiconductor Materials. His research combines fundamental Mathematical Physics with applications to device development, with an impact in medicine and the environment, with a current emphasis on the protection of water critical infrastructures.
He has been named SPIE Fellow in 2011 for his contributions to the Theory of Semiconductor Materials and Optics.
He created the TERA-MIR concept unifying THz and Mid Infrared Radiation and was the Chair of COST ACTION MP1204: TERA-MIR Radiation: Materials, Generation, Detection and Applications and Chair of the Series of NATO TERA-MIR Conferences (2009, 2012, 2015 and 2018). He coordinates the TERA-MIR Network (http://www.tera-mir.org).
He has been awarded the SPIE Innovation Awards in Quantum Sensing and Nano Electronics and Photonics (2019) for contributions to science and his service through organizing NATO TERA-MIR and COST.
He was a research associate at CBPF, Uni-Rostock and TU-Berlin, a visiting Lecturer at Uni-Bremen, Senior Researcher at Tyndall Institute, Professor and Chair of Theory of Semiconductor Materials and Optics at Sheffield Hallam University and Head of the Department of Condensed Matter Theory at the Institute of Physics of the Academy of Sciences of Czech Republic, before joining KU as Professor and Chair of the Physics Department.
GHz-THz nonlinear optics in semiconductor superlattices
Optical nonlinearities are of perpetual importance, notably connected with emerging new materials. Achieving a strong nonlinear response in the microwave to far-infrared spectral ranges is important for the development of GHz-THz technologies e.g. for noninvasive screening medical applications. Nonlinearities in semiconductors are well understood in near infrared and visible ranges, but little is known about the nonlinear response in the GHz and THz regime. Our aim is to deliver a state of the art simulator of intersubband transport and optical response of superlattices, based on Nonequilibrium Green’s Functions calculations, coupled with exact solutions of the corresponding Boltzmann equation. This will enable us to design structures with large nonlinear response controlled by external parameters. Prospective structures will be fabricated by Molecular Beam Epitaxy and characterized using spectroscopic, electrical transmission electrical microcopy and electron tomography measurements, thus providing a feedback for the simulator development. We will gain a deep understanding of microscopic phenomena underlying the nonlinearities and provide guidelines for designing components with application potential, such as frequency multipliers. The resulting optimized devices will be used in a spectrometer developed by our collaborators for breath analysis, which is a noninvasive medical screening applications with strong potential for early detection of respiratory diseases such as covid-19, before it becomes symptomatic. The resulting devices also have potential for water quality control. Water masks the sensitive spectroscopic detection of most dangerous substances and we will design our multipliers to operate in one the few GHz-THz low absorption windows of the water spectrum.
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Quantum Cascade Laser and Detector Simulator
The project involves development of software tools to design and simulate the behaviour of quantum cascade lasers (QCL's) working in terahertz and mid-infrared frequencies. The first QCL was constructed in 1994, and have significant advantages over conventional interband-based diode lasers. From a QCL the laser power generated can be up to 1000x greater, also QCLs can be manufactured to produce laser light over a wide range of frequencies not accessible to interband emitters. Applications of Terahertz emissions are now being heavily researched, as there are many possible applications. The most striking is within medical diagnostics, as THz emissions are non-ionising and non-radioactive, and therefore safer than X-rays and other forms of imaging. THz light can penetrate organic material to a depth of several cm and is absorbed in proportion to the water content of the organic matter or organ, and can be used to identify early stage tumours, gases within the body that indicate the presence of disease. Initial devices for imaging of teeth are being introduced, as an alternative to dental X-rays. Beyond medical applications, THz devices have potential to be used for explosive detection, and for "radar" type devices within cars, and there are many other potential applications. Many universities and companies in the world are working on medical diagnostic technology using THz imaging and QCLs. Current laser simulation tools, which can reduce drastically the price of development of new devices, are not capable of simulating QCL’s. The underlying physics is a lot more complex then in conventional lasers; most designers do not understand it. This project will lead to a user-friendly simulator, full of visual capabilities that will allow anyone with minimum physics understanding to design a QCL without necessarily knowing the complex underlying physics.
Photonic Functionalities in the Near and Mid Infrared
Photonic integrated circuits (PICs) represent a significant technological breakthrough. Unlike traditional circuits that rely on copper wires, PICs use waveguides to direct light, offering advantages such as higher data transfer rates, lower energy consumption, and more compact designs. This innovation is driving progress in telecommunications and computing while also paving the way for advanced fields like quantum computing and artificial neural networks, We have recently demonstrated that our designs are globally more efficient in the Near Infrared (NIR) [1]. A particularly promising area arises when integrated photonics shifts from the NIR to the mid-infrared (MIR) wavelength range. The MIR spectrum is especially valuable due to its fingerprint region, where unique molecular vibrational and rotation signatures enable precise and sensitive detection, as we have recently demonstrated with real time detection of ammonia in water [2]. This capability is crucial for applications in chemical sensing, environmental monitoring, and industrial process control, addressing the growing demand for precision and efficiency in these areas. Our current effort includes advanced waveguide structures that allow the manipulation and control of light. Preliminary MIR results are found in Refs. [3,4].
THz Spectroscopy for Metabolomics Medical Diagnostics
Metabolomics, is the systematic study of the chemical compounds - metabolites, which stem from cell metabolism. Metabolites and their concentrations are directly connected to the underlying biochemical activity and state of cells, tissues and organs, giving an opportunity for the development of new diagnostic techniques. In particular, analysis of chemical composition of exhaled breath and biological liquids (blood, saliva, urine) has been proven to provide important information about diseases and pathological processes in organisms. Our research employs the development and application of a THz nonstationary high-resolution spectrometer based on semiconductor superlattice multipliers, applied to investigate the dynamics of urine composition for cancer patients treated with chemotherapy, leading to the detection of early signs of nephrotoxicity. The molecular urine composition of healthy volunteers and cancer patients was compared and contrasted for reference. Nitriles have been detected in the urine samples of treated patients, indicating subclinical renal toxicity, which cannot be found by standard clinical methods. Comparison of the metabolite’s concentration dynamics with side-effects, appearing during chemotherapy, can help to individuate patients, prone to serious complications, and correct the treatment. Our devices are gamechangers for THz spectroscopy of liquids: they allow to span 4 different frequency ranges, for a general evaluation of most substances found in the liquid and then allow us to select a range that bypasses strong absorption lines from substances such as water and ammonia, that may mask the detection of the target metabolites. This opens the possibility of analyzing a plethora of liquids that cannot be accessed by existing THz sources and detectors.
1. M.F. Pereira et al., Sci Rep 10, 15950 (2020).
2. V. Vaks et al., Sci Rep 12, 18117 (2022).
PhD Student Fellowships for the projects: Quantum Cascade Laser and Detector Simulator; GHz-THz Nonlinear Optics in Semiconductor Superlattices; Photonic Functionalities
