Hugo Enrique Hernández Figueroa

• Full Professor
• Professor (Full) at State University of Campinas (UNICAMP)

All-dielectric metasurfaces supporting resonant quasi-bound states in the continuum (qBIC) offer an ideal platform for various applications relying on intense light-matter interaction in highly localized and enhanced fields. Here, we propose a dielectric metasurface composed of hollow GaP nanocuboid quadrumers periodically arranged on a silica subs...

Presentation of a project aimed at the development of innovative educational materials for full-time public schools from theory to practice: learning experiences with energy matrices. This is an educational initiative that aims to disseminate knowledge about sources of electrical energy and their implications.

O projeto apresentado, intitulado "Robótica para Todos: Criando Recursos Educacionais para Jovens Talentos Engajados em Iniciativas Educacionais do Terceiro Setor", é motivado pela crescente demanda por oportunidades educacionais inclusivas e acessíveis para jovens de diversas origens sociais, com foco específico nas organizações do terceiro setor....

We introduce a novel technique for designing color filter metasurfaces using a data-driven approach based on deep learning. Our innovative approach employs inverse design principles to identify highly efficient designs that outperform all the configurations in the training dataset, which consists of 810 distinct geometries solely. By combining Mult...

Analogue optical computing offers a promising approach for developing super‐fast computation techniques, benefiting from its extraordinary parallel processing capability, low energy consumption, and high integrability compared to digital electronic technologies. In this work, a reconfigurable spatiotemporal optical signal processor using the phase‐...

A novel hybrid multimode interferometer for sensing applications operating with both TE and TM polarizations simultaneously is proposed and numerically demonstrated. The simulations were performed assuming an operating wavelength of 633 nm with the goal of future use as a biosensor, but its applications extend beyond that area and could be adapted...

A compact magnetless isolator for optical communication systems based on a ring resonator with an outer layer made of silicon and an inner layer made of a magneto-optical material that does not require an external magnet to keep its magnetization saturated is suggested. Three-dimensional computational simulations of the device performed with the fu...

One of the challenges in using integrated optical biosensors is their ability to operate in environments outside laboratories. This occurs, among other reasons, because suitable source coupling components are not considered at the design stage. In this work, a highly selective, compact and efficient in-coupling method is proposed with the aim to de...

In this work, we present the modal analysis and the design consideration of a hybrid plasmonic waveguide (HPWG) based sensor. The device has a very simple structure and uses Silicon nitride (SiN) technology compatible with CMOS foundries, a top cladding of SiO2 and a thin gold layer. This noble metal is suitable for its stability, high sensitivity...

The highly conductive composite based on graphite nanobelts/ultra-high-molecular-weight polyethylene (UHMWPE) was developed using hot calendering at temperatures below the polymer melting point. The fabricated material exhibits excellent electrical conductivity (up to 40 S cm⁻¹), high efficiency of electromagnetic interference shielding (near 35 dB...

Optical interferometers are important and versatile building blocks in integrated optics. They can present a wide variety of operating mechanisms and have several distinct applications, where one of them is optical sensing. The multimode interferometer (MMI) is an established structure but has only recently received attention as a sensing device. T...

Quasi-dark resonances exhibiting antiferromagnetic order are theoretically investigated in a near-infrared metasurface composed of square slotted rings etched in a thin silicon layer on glass substrate. Access to the quasi-dark mode is achieved by reducing the symmetry of the metasurface according to the findings of a detailed group theory analysis...

Flexible films fabricated using two different conductive pastes based on mixtures of graphene and biopolymers have been used to fabricate passive Ultra High Frequency (UHF) Radio Frequency Identification (RFID) tags consisting of a dipole antenna and a microchip on a paper substrate. The preparation of these composite materials, in addition to the...

A three-port circulator for optical communication systems comprising a photonic crystal slab made of a magneto-optical material in which an magnetizing element is not required to keep its magnetic domains aligned is suggested for the first time. By maximizing the incorporation of europium to its molecular formula, the magneto-optical material can r...

This paper presents a fast factorized back-projection (FFBP) algorithm that can satisfactorily process real P-band synthetic aperture radar (SAR) data collected from a spiral flight pattern performed by a drone-borne SAR system. Choosing the best setup when processing SAR data with an FFBP algorithm is not so straightforward, so predicting how this...

A generalization of the concept of multimode interference sensors is presented here for the first time, to the best of our knowledge. The existing bimodal and trimodal sensors correspond to particular cases of those interference sensors. A thorough study of the properties of the multimode waveguide section provided a deeper insight into the behavio...

We propose and demonstrate a polarization splitter and rotator (PSR) oper- ating in the range of 1530 to 1590 nm, built on the SOI platform and based on a new bow tie converter TM0-to-TE1. Comparing with other compact (< 100 µm length) state-of-the-art photonic integrated devices, the proposed device exhibits simultaneously the lowest crosstalk and...

A new compact optical circulator based on a photonic crystal made of a triangular lattice of air holes etched in a magneto-optical material that does not require an external DC magnetic field to keep its saturated magnetic state is presented. The design has a threefold rotational symmetry and it consists of three single-mode waveguides and one reso...

SU-8 is an attractive platform for the development of smart biochips owing to its high aspect ratio of micro/nanostructures fabrication and remarkable optical and biocompatible properties. However, few works have explored sub-micron SU-8 thin films for applications in new generations of portable bioanalytical devices. In this work we discuss surfac...

The articles in this special section focus on photonic antennas. Early attempts in developing Photonic Antennas can be traced back to the 1990’s with the design and fabrication of micrometer-scale infrared and visible light antennas. From that time on, interest in this emerging research field has expanded rapidly, with growing sophistication of des...

This research introduces a numerical design of an air-core vortex polymer optical fiber in cyclic transparent optical polymer (CYTOP) that propagates 32 orbital angular momentum (OAM) modes, i.e., it may support up to 64 stable OAM-states considering left- and right-handed circular polarizations. This fiber seeks to be an alternative to increase th...

Aiming efficient multiple simultaneous detection, two different designs of 1×N power splitters for single source feeding of an N-array biosensors operating at 1550 nm are here proposed and thoroughly compared and discussed. Taking into account the need for micro guiding structures, simpler and cheaper manufacturing processes, SU-8 polymer is adopte...

Differential synthetic aperture radar interferometry (DInSAR) has been widely applied since the pioneering space-borne experiment in 1989, and subsequently with the launch of the ERS-1 program in 1992. The DInSAR technique is well assessed in the case of space-borne SAR data, whereas in the case of data acquired from aerial platforms, such as airpl...

Accurate, high-resolution maps of for crop growth monitoring are strongly needed by precision agriculture. The information source for such maps has been supplied by satellite-borne radars and optical sensors, and airborne and drone-borne optical sensors. This article presents a novel methodology for obtaining growth deficit maps with an accuracy do...

Sorting machines use computer vision (CV) to separate food items based on various attributes. For instance, sorting based on size and colour are commonly used in commercial machines. However, detecting external defects using CV remains an open problem. This paper presents an experimental contribution to external defect detection using deep learning...

We designed Extreme Learning Machines (ELM) for calculating band structures (BST) of randomly-generated bi-dimensional (2D) photonic crystals and demonstrated fast-training ELM models able to perform fast and accurate BST computations.

This work implements and demonstrates an interferometric transducer based on a trimodal optical waveguide concept. The readout signal is generated from the interference between the fundamental and second-order modes propagating on a straight polymer waveguide. Intuitively, the higher the mode order, the larger the fraction of power (evanescent fiel...

The integrated analysis of spatial distributions of the electric potential, electric field, temperature and tissue damage generated by multiple-arrays of straight needle electrodes inserted into tumors is one of the most significant challenges to improve electrochemical treatment effectiveness. This paper simulates these spatial profiles generated...

This work proposes a system capable of obtaining the geometric measurements of a Yagi antenna using digital image processing. The objective is to obtain the measurements automatically in 3D using the CST STUDIO software, which is a program specializing in electromagnetic simulations in 3D. The antenna images are acquired by means of a depth sensor...

Synthetic Aperture Radar (SAR) has become a powerful remote sensing tool during the last 25 years. Most relevant products are three dimensional and projected on a cartographic system: topographic, thematic and change-detection maps. Starting with the requirements of precision agriculture, subsurface tomography, subsidence and cartography a low weig...

This article presents, to the best of our knowledge, the study, software simulation and fabrication of a biconical antenna with a lightning protection system operating in a wide frequency range from 20 MHz to 3 GHz. The purpose of this system is to provide protection against atmospheric electric discharge in regions with a high incidence of lightni...

A theoretical study regarding wired and wireless link performance by using a dielectric resonator nanoantenna (DRNA) integrated to a metal-dielectric-metal-dielectric (MDMD) nanostrip waveguide is evaluated. Near- and far-field coupling characteristics in receiving (RX) and transmitting (TX) modes of this DRNA are investigated at optical frequencie...

This work presents a microstrip array antenna designed for a synthetic aperture radar to be operated on board a multirotor drone. The array was designed and simulated with a main concern of back-clutter rejection. Lastly, the antenna was manufactured and tested with the radar.

A novel full-wave method to perform mode analysis on waveguides is introduced in this paper. The core of the method is based on an Interior Penalty Discontinuous Galerkin (IPDG) discretization of the vector wave equation. With an appropriate penalty function a spurious-free and high accuracy method is achieved. We prove the efficiency of the propos...

Despite increasing efforts in studying non-diffracting optical beams, much less work has been done in the characterization and application of these beams for Millimeter and Sub-millimeter Wavelengths. This is because, in order to generate those beams for long distances, large equipment and antennas are required. However, if shorter distances are co...

In this work, dispersion relations (DRs) of photonic crystals (PhCs) are computed by Multilayer Perceptron (MLP) and Extreme Learning Machine (ELM) Artificial Neural Networks (ANNs). Bi- and tri-dimensional optimized structures presenting distinct DRs and photonic band gaps (PBGs) were selected for case studies. Optical properties of a set of PhCs...

In this work we demonstrate the use of a dielectric barrier discharge plasma for the treatment of SU-8. The resulting hydrophilic surface displays a 5° contact angle and (0.40 ± 0.012) nm roughness. Using this technique we also present a proof of concept of IgG and prostate specific antigen biodetection on a thin layer of SU-8 over gold via surface...

Dielectric barrier discharge (DBD) plasma was used to change the wettability of a SU-8 photoresist, reducing the contact angle and improving the surface smoothness. As most polymers, SU-8 has hydrophobic surfaces which prevents the adhesion of biological samples when used to fabricate biochemical sensors. Here, DBD Plasma treatment was conducted ov...

We use the two dimensional finite element method (2D-FEM) in the frequency domain to characterize the transmission properties of 90⁰-bend periodic segmented waveguides (PSWs). We investigated the dependence of the transmission coefficient and the mode profile of PSWs on the bending radius, the waveguide duty cycle, and the operating wavelength. We...

The photonic device modeling and optimizations has, commonly, required sophisticated computational approaches. This work presents an efficient Evolutionary Strategy (ESCH) algorithm to optimize unbalanced photonic coupler devices that are benchmarked with other algorithms. The successful results motivated the free online distribution of this algori...

Photonic antennas are critical in applications such as spectroscopy, photovoltaics, optical communications, holography, and sensors. In most of those applications, metallic antennas have been employed due to their reduced sizes. Nevertheless, compact metallic antennas suffer from high dissipative loss, wavelength-dependent radiation pattern, and th...

We modeled Extreme Learning Machine feed-forward artificial neural network for estimating band diagrams of tri-dimensional photonic crystals and demonstrated a simple approach for speedy computations.

A theoretical study regarding to coupling efficiency between a dielectric resonator nanoantenna (DRNA) integrated to a metal-dielectric-metal-dielectric nanostrip waveguide (NW), and free space is evaluated.

We use numerical simulations to show that, even under common perturbations such as waveguide bends, pedestal waveguides are suited for stable propagation of modes carrying orbital angular momentum (OAM) in integrated devices.

We present a novel method for the analysis of intricate optical waveguides. The method relies on a discretization of the Maxwell’s vector wave equation with an Interior Penalty Discontinous Galerkin Method (IPDG) combined with a standard FEM. This method is spurious-free for a large parameter that penalizes the tangential flux. We present results f...

We designed a Multilayer Perceptron (MLP) feed-forward Artificial Neural Network for estimating band diagrams of tri-dimensional photonic crystals. We show a simple and fast-training MLP model able to build accurate band diagrams through speedy computations.

In this work, we present a design for a high-bandwidth (> 40 GHz) O-band Silicon Mach-Zehnder modulator using a lateral junction and compare it with an interleaved junction in terms of efficiency, loss and bandwidth.

Photonics has been widely explored in computing and communications, mainly to rationalize the relationship between device size minimization and data processing/transmission maximization. Generally driven by optimization and modeling techniques, the design of photonic devices is often performed by bio-inspired algorithms integrated to electromagneti...

Low loss optical interconnects in hybrid integrated platforms for silicon photonics are likely to become increasingly important to overcome power consumption limitations in telecom packaging applications. Here, we show a short taper device that effectively interconnects electro-optic polymer modulator waveguides and silicon-on-insulator platforms w...

In this work we present the performance of metallic (copper and aluminum) and graphene buckypaper based microstrip transmission lines and the comparison between these device configurations. The graphene buckypapers were deposited by a simple vacuum filtration method, leading to freestanding paper with 350 um thickness and diameter up to 1.2 inches....

In this work we present a fabrication process to obtain a low-loss waveguide in the photo-curable resin SU-8 using direct laser writing at 405 nm wavelength. Polymer-based devices offer low-cost prototype fabrication, fabrication flexibility, reliability, low power consumption and potential for mass production. These characteristics, coupled with i...

A multiphysics study of the electromagnetic behavior of a filter designed for use in high-power microwave systems is presented. In the past, the methodology used to design filters generally assumed ideal working conditions for these devices. However, when such filters are used in a real environment, factors such as temperature and working power aff...

This article presents a novel Three-Dimensional (3D) Vector Finite Element Method to solve eigenvalue problems for periodic structures. With the formulation, numerical investigations of photonic crystals and subwavelength grating waveguide in a silicon-on-insulator platform have been performed. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol L...

In the last years, remote monitoring and sensing have had an important role in the plans of the national defense strategy in order to guard the land borders of a country. The Brazilian project SISFRON (Sistema de Monitoramento Integrado das Fronteiras Terrestres) is an example of monitoring and sensing application. In this way, many research effor...

This paper presents a design and simulation of a low noise amplifiers (LNA) with all passives elements embedded on low temperature co-fired ceramic (LTCC) substrate. Simulation results in ANSYS Designer and CST Studio Suite reveal that the proposed LNA has a flat-gain of 23.34 dB from 300 to 500 MHz, a noise figure below 0.73 dB and a compact size...

This paper presents the experimental results of an edge coupling between a conical micro-lensed fiber and a chip. Coupling is an important issues in the packaging process. Loss power and misalignment tolerance values are discussed.

Poster presentation at LAOP about measuerements in fiber-chip edge coupling.

We demonstrate an ultra-compact silicon on insulator antenna with 3.2 µm 2 footprint and broadside radiation from 1470 nm to 1550 nm for applications in fiber-to-chip coupling and phased arrays.

We demonstrate an ultra-compact silicon on insulator antenna with 3.2 µm 2 footprint and broadside radiation from 1470 nm to 1550 nm for applications in fiber-to-chip coupling and phased arrays.

We demonstrate an ultra-compact silicon on insulator antenna with 3.2 µm 2 footprint and broadside radiation from 1470 nm to 1550 nm for applications in fiber-to-chip coupling and phased arrays.

We demonstrate an ultra-compact silicon on insulator antenna with 3.2 µm 2 footprint and broadside radiation from 1470 nm to 1550 nm for applications in fiber-to-chip coupling and phased arrays.

We demonstrate an ultra-compact silicon on insulator antenna with 3.2 µm 2 footprint and broadside radiation from 1470 nm to 1550 nm for applications in fiber-to-chip coupling and phased arrays.

A new approach to reduce the bending loss of the fundamental quasi-transverse magnetic mode in optical waveguides is presented. A much lower bending loss is achieved by designing waveguides that use as substrate or cladding an anisotropic metamaterial made of multilayers of thin films of germanium and porous silica instead of a conventional silica...

We numerically demonstrate a bending loss reduction of up to~2.5dB/90o for the quasi-TM- mode of a Silicon-on-Insulator waveguide of core size (440x220nm) with a bending radius of 1 µm, using as substrate multilayers of Si/SiO2.

An efficient design approach of directional couplers based multiplexers/demultiplexers for optical communication applications, by using an adapted artificial immune network algorithm for optimization (opt-AiNet), is presented and validated by using the beam propagation method. Two key multiplexers/demultiplexers based on planar waveguides and optic...