Mauro Fernandes Pereira
@ku.ac.ae
Professor and Chair of Physics, KUST
Khalifa University
RESEARCH INTERESTS
Nonequilibrium Many Body Theory of Transport and Optics in Semiconductors; Nonlinear Optics; GHz-THz-Mid Infrared generation, detection and applications
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
Arnab Ganguly, Humaira Zafar, Calvyn Travis Howells, Mauro Fernandes Pereira, and Gobind Das
Wiley
Nanosphere lithography, a low‐cost fabrication technique, depends on the self‐assembly of nanoscale features to create nanostructures in a hexagonally close‐packed structure. In this article, the fabrication of 3D nanostructures over a large surface‐area with anisotropy along the growth direction through the combination of chemical and physical plasma etching is reported. The anisotropy stems from etching the nanosphere mask and the substrate at different rates. Due to the dynamic masking effect, a systematic variation of etching time gives rise to intriguing nanostructures with sharp edges that have strong potential for plasmonic applications, with the possibility of manipulating electromagnetic radiation. The structures obtained include nanocylinders, truncated hexagon‐based pyramids, circular pads on a conical base, and nanocones from a single‐layer nanosphere mask. Simulations of the fabrication process offer further insight into the understanding of nanostructure formation. A good agreement between predicted results and experiments confirms the potential of our numerical design. In addition, the optical properties of the nanostructures are investigated by UV–vis and the experimental findings are consistent with simulations based on a finite‐difference time‐domain method. The nanostructures described in this study contribute to the emerging 3D plasmonics and 3D magnonics, with strong potential for a significant impact on biosensor applications.
Humaira Zafar and M. F. Pereira
Institute of Electrical and Electronics Engineers (IEEE)
Abdullah Al-Ateqi and Mauro Fernandes Pereira
Springer Science and Business Media LLC
Vladimir Vaks, Vladimir Anfertev, Maria Chernyaeva, Elena Domracheva, Anton Yablokov, Anna Maslennikova, Alla Zhelesnyak, Alexei Baranov, Yuliia Schevchenko, and Mauro Fernandes Pereira
Springer Science and Business Media LLC
Humaira Zafar, Bruna Paredes, Inas Taha, Juan E. Villegas, Mahmoud Rasras, and Mauro F. Pereira
Institute of Electrical and Electronics Engineers (IEEE)
Broadband and ultra-low crosstalk integrated silicon superlattice waveguides are proposed and demonstrated, enabling high-density waveguide integration. The superlattice waveguides are implemented as S-shaped adiabatic bends that yield ultra-low crosstalks in the neighboring channels, and an extremely low insertion loss, for the TE polarization. Special materials or complex fabrication steps are not required. The bent superlattice waveguides are measured to have an average insertion loss <inline-formula><tex-math notation="LaTeX">$\\leq$</tex-math></inline-formula> 0.1 dB for all channels. The average crosstalk values are <inline-formula><tex-math notation="LaTeX">$\\leq$</tex-math></inline-formula> −37.8 dB and <inline-formula><tex-math notation="LaTeX">$\\leq$</tex-math></inline-formula> -45.2 dB, in the first nearest neighboring waveguide and the second nearest neighboring waveguide, respectively. The transmission spectra are measured over the wavelength ranges of (1.24 μm to 1.38 μm) and (1.45 μm to 1.65 μm), covering both communication wavelengths of 1310 and <inline-formula><tex-math notation="LaTeX">$1550 \\,\\mathrm{n}\\mathrm{m}$</tex-math></inline-formula>. The simulation results predict an efficient broadband performance over the <inline-formula><tex-math notation="LaTeX">$500 \\,\\mathrm{n}\\mathrm{m}$</tex-math></inline-formula> wavelength range (<inline-formula><tex-math notation="LaTeX">$1200 \\,\\mathrm{n}\\mathrm{m}$</tex-math></inline-formula> to <inline-formula><tex-math notation="LaTeX">$1700 \\,\\mathrm{n}\\mathrm{m}$</tex-math></inline-formula>), covering all O, E, S, C, L & U bands. The proof of concept was done for a silicon-on-insulator platform and the approach is applicable to other waveguide geometries and integrated photonic platforms.
Humaira Zafar, Bruna Paredes, Juan Villegas, Mahmoud Rasras, and Mauro Fernandes Pereira
Optica Publishing Group
An efficient, dual-polarization silicon waveguide array with low insertion losses and negligible crosstalks for both TE and TM polarizations has been reported using S-shaped adiabatically bent waveguides. Simulation results for a single S-shaped bend show an insertion loss (IL) of ≤ 0.03 dB and ≤ 0.1 dB for the TE and TM polarizations, respectively, and TE and TM crosstalk values in the first neighboring waveguides at either side of the input waveguide are lower than −39 dB and −24 dB, respectively, over the wavelength range of 1.24 µm to 1.38 µm. The bent waveguide arrays exhibit a measured average TE IL of ≈ 0.1 dB, measured TE crosstalks in the first neighboring waveguides are ≤ −35 dB, at the 1310 nm communication wavelength. The proposed bent array can be made by using multiple cascaded S-shaped bends to transmit signals to all optical components in integrated chips.
Renan de S. Teixeira, Mauro F. Pereira, and Jorge P. Zubelli
Elsevier BV
Vladimir Vaks, Vladimir Anfertev, Maria Chernyaeva, Elena Domracheva, Anton Yablokov, Anna Maslennikova, Alla Zhelesnyak, Alexei Baranov, Yuliia Schevchenko, and Mauro Fernandes Pereira
Springer Science and Business Media LLC
AbstractA THz nonstationary high-resolution spectrometer based on semiconductor superlattice multipliers is applied to investigate the dynamics of urine composition for cancer patients treated with chemotherapy. The molecular urine composition of healthy volunteers and cancer patients was compared and contrasted. We have found a set of nitriles that either appeared after chemotherapy or increased in content, which are expected as a result of bio-chemical damage to the liver. While no damage can be detected at this stage by existing clinical methods, the identified nitriles are candidates for further large-scale systematic testing towards markers for nephrotoxicity of chemotherapy at an early stage of the treatment, when conventional diagnostics cannot identify substantial organ damage. Comparing the metabolite concentration dynamics with side effects during chemotherapy might then help individuate patients prone to severe complications and correct the treatment. Our devices are game-changers for THz spectroscopy of liquids: they allow spanning four different frequency ranges for a general evaluation of most substances found in the liquid and selecting a spectral interval that bypasses the strong absorption lines from substances such as water and ammonia, which may otherwise mask the detection of the target metabolites.
Mauro Fernandes Pereira
MDPI AG
Semiconductor superlattices are proven nanomaterials for THz nonlinear optics by means of high order harmonic generation. Seminal approaches leading to a perfectly antisymmetric current-voltage (I–V.) curve predict the generation of odd harmonics only in the absence of a bias. However, even harmonics at high orders have been detected in several experiments. Their generation has been explained by considering deviations from the current flow symmetry that break the exact antisymmetry of the I–V. curve. In this paper, we focus on another issue found experimentally that has also not been explained, namely the harmonic power output asymmetry from negative to positive applied bias. Once more, breaking the I–V. flow symmetry explains the experiments and leads to a further tool to design the power output of these materials. Furthermore, a new approach for the Boltzmann Equation under relaxation-rate approximation eliminates numerical difficulties generated by a previous theory. This leads to very efficient analytical expressions that can be used for both fundamental physics/optics/material sciences and realistic device development and simulations.
Humaira Zafar, Yanfen Zhai, Juan E. Villegas, Florent Ravaux, Kenneth L. Kennedy, Mauro F. Pereira, Mahmoud Rasras, Atif Shamim, and Dalaver H. Anjum
Optica Publishing Group
A compact, ultra-broadband and high-performance silicon TE-pass polarizer is proposed and demonstrated experimentally. It is based on partially-etched (ridge) waveguide adiabatic S-bends, input/output tapers and side gratings on a silicon-on-insulator (SOI) platform. A compact footprint and weak back reflections are obtained due to the bent waveguide and the tapers, respectively. An extremely high extinction ratio is achieved by scattering the undesired light in the slab section using the side gratings. The 3D FDTD simulations show a TE loss less than 0.3 dB and an extinction ratio greater than 30 dB over a 500 nm wavelength range (1200 nm to 1700 nm). Measured results show a high TM loss (> 35 dB) and a low TE insertion loss (< 1.5 dB), over a 200 nm wavelength range (1450 nm to 1650 nm). The measured TE loss is < 0.6 dB at a communication wavelength of 1550 nm. The footprint of the optimized design is 65 µm × 20 µm.
Philippe Cousin, Anastasia Moumtzidou, Anastasios Karakostas, Lefteris Gounaridis, Christos Kouloumentas, Mauro Fernandes Pereira, Apostolos Apostolakis, Paula Gorrochategui, Guillaume Aoust, and Bérengère Lebental
Springer International Publishing
M.F. Pereira and A. Apostolakis
IEEE
A hybrid approach combining Nonequilibrium Green’s Fuctions with solutions of the Boltzman equation, delivers voltage and intrinsic asymmetry control of nonlinearities in semiconductor superlattices. Unexpected nonlinear behavior is predicted for high harmonics as a result of voltage control.
Mauro Fernandes Pereira and Apostolos Apostolakis
MDPI AG
Recent studies have predicted a strong increase in high harmonic emission in unbiased semiconductor superlattices due to asymmetric current flow. In parallel, an external static bias has led to orders of magnitude control of high harmonics. Here, we study how this control can affect the operation of superlattice multipliers in a range of input frequencies and powers delivered by commercially available GHz sources. We show that the strongly nonlinear behavior can lead to a very complex scenario. Furthermore, it is natural to ask what happens when we combine both asymmetry and voltage control effects. This question is answered by the simulations presented in this study. The efficiency of high-order even harmonics is increased by the combined effects. Furthermore, the development of ‘petals’ in high-order emission is shown to be more easily achieved, opening the possibility to very interesting fundamental physics studies and more efficient devices for the GHz–THz range.
Yuliaa Schevchenko, Apostolos Apostolakis, and Mauro F. Pereira
Springer Netherlands
G. Kamarchuk, A. Pospelov, A. Savytskyi, V. Gudimenko, V. Vakula, A. Herus, D. Harbuz, L. Kamarchuk, and M. F. Pereira
Springer Netherlands
Humaira Zafar, Mauro Fernandes Pereira, Kenneth L. Kennedy, and Dalaver Hussain Anjum
AIP Publishing
In this paper, we demonstrate a broadband, low-loss, compact, and fabrication-tolerant polarization splitter and rotator (PSR) on a silicon-on-insulator platform. The PSR is based on an asymmetric directional coupler (ADC), which is covered with SiO2 from the top to make it compatible with the standard metal back end of line (BEOL) process. Conventional ADC-based PSRs suffer from stringent fabrication requirements and relatively low bandwidth, while the proposed bent-tapered design is highly insensitive to the fabrication errors (＞70 nm tolerance on the coupling gap) with an enlarged bandwidth and a compact footprint of 53 µm × 7 µm. It yields a polarization conversion loss less than 0.7 dB, a transverse electric (TE) insertion loss better than 0.3 dB, an ultra-low crosstalk with the TE extinction better than 30 dB, and the transverse magnetic extinction better than 25 dB, over a 200 nm wavelength range (1.5 µm–1.7 µm), in both ports. At the 1.55 µm wavelength, the calculated ultra-low polarization conversion loss and TE insertion loss are 0.27 dB and 0.08 dB, respectively.
M. F. Pereira, V. Anfertev, Y. Shevchenko, and V. Vaks
Springer Science and Business Media LLC
Abstract Optical nonlinearities are of perpetual importance, notably connected with emerging new materials. However, they are difficult to exploit in the gigahertz–terahertz (GHz–THz) range at room temperature and using low excitation power. Here, we present a clear-cut theoretical and experimental demonstration of real time, low power, room temperature control of GHz–THz nonlinearities. The nonlinear susceptibility concept, successful in most materials, cannot be used here and we show in contrast, a complex interplay between applied powers, voltages and asymmetric current flow, delivering giant control and enhancement of the nonlinearities. Semiconductor superlattices are used as nonlinear sources and as mixers for heterodyne detection, unlocking their dual potential as compact, room temperature, controllable sources and detectors. The low input powers and voltages applied are within the range of compact devices, enabling the practical extension of nonlinear optics concepts to the GHz–THz range, under controlled conditions and following a predictive design tool.
Apostolos Apostolakis and Mauro F. Pereira
Walter de Gruyter GmbH
AbstractSemiconductor superlattices are strongly nonlinear media offering several technological challenges associated with the generation of high-frequency Gigahertz radiation and very effective frequency multiplication up to several Terahertzs. However, charge accumulation, traps and interface defects lead to pronounced asymmetries in the nonlinear current flow, from which high harmonic generation stems. This problem requires a full non-perturbative solution of asymmetric current flow under irradiation, which we deliver in this paper within the Boltzmann-Bloch approach. We investigate the nonlinear output on both frequency and time domains and demonstrate a significant enhancement of even harmonics by tuning the interface quality. Moreover, we find that increasing arbitrarily the input power is not a solution for high nonlinear output, in contrast with materials described by conventional susceptibilities. There is a complex combination of asymmetry and power values leading to maximum high harmonic generation.
A. Apostolakis and M. F. Pereira
IEEE
This talk starts with an outline of our hybrid approach combining Nonequilibrium Green's Functions with the Boltzmann equation for the nonlinear response of semiconductor superlattices. The nonlinearities are controllable and very good agreement has been found between theory and experiments. Next, we address the efficiency of the superlattices as frequency multipliers and their feasibility for room temperature THz radiation sources based on multiplication of GHz inputs.
Apostolos Apostolakis and Mauro F. Pereira
SPIE-Intl Soc Optical Eng
Abstract. A theoretical study is presented to assess the performance of semiconductor superlattice (SL) multipliers as a function of the currently available input power sources. The prime devices that are considered as input power sources are Impatt diodes, InP Gunn devices, SL electron devices, and backward wave oscillator sources. These sources have been successfully designed to deliver input radiation frequencies in the range from 0.1 to 0.5 THz. We discuss the harmonic power generation of both odd and even harmonics by implementing an ansatz solution stemmed from a hybrid approach combining nonequilibrium Green’s functions and the Boltzmann kinetic equation.
Apostolos Apostolakis and Mauro F. Pereira
SPIE
This paper implements a simple optical method to forecast power output of superlattice multipliers which are subjected to an external GHz-THz field. These results complement a recent study which addressed the harmonic conversion efficiency in semiconductor superlattices by interface roughness design. Applying a strong ac field on such a device pumps energy into the system, which is then converted to radiation at harmonics of the pump frequency. Here we investigate the odd harmonics generation in an unbiased superlattice at room temperature, after excitation by input signals in a wide frequency range which can provided by realistic devices.
A. Apostolakis and Mauro F. Pereira
AIP Publishing
In semiconductor superlattices, when Bragg oscillating electrons interact with an input electromagnetic field, frequency multiplication is possible. An ideal superlattice has a purely antisymmetric voltage current response and can thus produce only odd harmonics. However, real world superlattices can also have even harmonic response and that increases the range of possible output frequencies. These effects have been recently explained with a predictive model that combines an Ansatz solution for the Boltzmann Equation with a Nonequilibrium Green’s Functions approach. This predictive tool, coupled with recent progress on GHz input sources, support the growing interest in developing compact room temperature devices that can operate from the GHz to the THz range. The natural question to ask is what efficiencies can be expected. This paper addresses this issue by investigating power-conversion efficiency in irradiated semiconductor superlattices. Interface imperfections are consistently included in the theory and they strongly influence the power output of both odd and even harmonics. Good agreement is obtained for predicted odd harmonic outputs with experimental data for a wide frequency range. The intrinsic conversion efficiency used is based on the estimated amplitude of the input field inside the sample and thus independent of geometrical factors that characterize different setups. The method opens the possibility of designing even harmonic output power by controlling the interface quality.In semiconductor superlattices, when Bragg oscillating electrons interact with an input electromagnetic field, frequency multiplication is possible. An ideal superlattice has a purely antisymmetric voltage current response and can thus produce only odd harmonics. However, real world superlattices can also have even harmonic response and that increases the range of possible output frequencies. These effects have been recently explained with a predictive model that combines an Ansatz solution for the Boltzmann Equation with a Nonequilibrium Green’s Functions approach. This predictive tool, coupled with recent progress on GHz input sources, support the growing interest in developing compact room temperature devices that can operate from the GHz to the THz range. The natural question to ask is what efficiencies can be expected. This paper addresses this issue by investigating power-conversion efficiency in irradiated semiconductor superlattices. Interface imperfections are consistently included in the theory ...
M. F. Pereira, V. Anfertev, and V. Vaks
IEEE
This talk discusses a concept to study nonlinear optics through controllable nonlinearities in semiconductor superlattices. A predictive microscopic Nonequilibrium Green's Functions approach is used to deliver input to a relaxation-rate approximation approach leading to analytical expressions for the nonlinear polarization at arbitrary orders. These results open the possibility of extending the whole field of nonlinear optics to the GHz-THz range and the potential to design materials and devices for a large number of applications, including spectroscopy of biomolecules, which typically have strong GHz-THz resonances.
M. F. Pereira
IEEE
This talk will deliver a review of a set of analytical equations for both luminescence and absorption of semiconductors, which have proven useful to describe dilute semiconductors. The algorithms can be a useful tool for superlattices and other effective three dimensional materials treated with the anisotropic medium approach.