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A. Fantoni
ADEETC-ISEL-Instituto Politécnico de Lisboa, 1949-014 Lisbon, Portugal

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Journal article
Published: 30 June 2020 in Optica Pura y Aplicada
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ACS Style

Alessandro Fantoni. Theory and FDTD simulations of an amorphous silicon planar waveguide structure suitable to be used as a surface plasmon resonance biosensor. Optica Pura y Aplicada 2020, 53, 1 -8.

AMA Style

Alessandro Fantoni. Theory and FDTD simulations of an amorphous silicon planar waveguide structure suitable to be used as a surface plasmon resonance biosensor. Optica Pura y Aplicada. 2020; 53 (2):1-8.

Chicago/Turabian Style

Alessandro Fantoni. 2020. "Theory and FDTD simulations of an amorphous silicon planar waveguide structure suitable to be used as a surface plasmon resonance biosensor." Optica Pura y Aplicada 53, no. 2: 1-8.

Journal article
Published: 01 June 2020 in The European Physical Journal Applied Physics
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Amorphous silicon PECVD photonic integrated devices are promising candidates for low cost sensing applications. This manuscript reports a simulation analysis about the impact on the overall efficiency caused by the lithography imperfections in the deposition process. The tolerance to the fabrication defects of a photonic sensor based on surface plasmonic resonance is analysed. The simulations are performed with FDTD and BPM algorithms. The device is a plasmonic interferometer composed by an a-Si:H waveguide covered by a thin gold layer. The sensing analysis is performed by equally splitting the input light into two arms, allowing the sensor to be calibrated by its reference arm. Two different 1 × 2 power splitter configurations are presented: a directional coupler and a multimode interference splitter. The waveguide sidewall roughness is considered as the major negative effect caused by deposition imperfections. The simulation results show that plasmonic effects can be excited in the interferometric waveguide structure, allowing a sensing device with enough sensitivity to support the functioning of a bio sensor for high throughput screening. In addition, the good tolerance to the waveguide wall roughness, points out the PECVD deposition technique as reliable method for the overall sensor system to be produced in a low-cost system. The large area deposition of photonics structures, allowed by the PECVD method, can be explored to design a multiplexed system for analysis of multiple biomarkers to further increase the tolerance to fabrication defects.

ACS Style

Alessandro Fantoni; João Costa; Paulo Lourenço; Manuela Vieira. Computer simulation study about the dependence of amorphous silicon photonic waveguides efficiency on the material quality. The European Physical Journal Applied Physics 2020, 90, 30502 .

AMA Style

Alessandro Fantoni, João Costa, Paulo Lourenço, Manuela Vieira. Computer simulation study about the dependence of amorphous silicon photonic waveguides efficiency on the material quality. The European Physical Journal Applied Physics. 2020; 90 (3):30502.

Chicago/Turabian Style

Alessandro Fantoni; João Costa; Paulo Lourenço; Manuela Vieira. 2020. "Computer simulation study about the dependence of amorphous silicon photonic waveguides efficiency on the material quality." The European Physical Journal Applied Physics 90, no. 3: 30502.

Conference paper
Published: 29 April 2020 in Collaboration in a Hyperconnected World
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Integrated optics are a contemporaneous reality in which thin-film technology and methods utilized in the development of integrated circuitry, are applied to both optical circuits and devices. This provides systems that show improved characteristics when compared to their electronic counterparts. Optical systems enable wider bandwidth operation, less power consumption, more immunity to interference and higher cost-efficiency. These features definitely represent a huge improvement in our daily lives when completely embedded in Information and Communications Technologies, replacing a large percentage of contemporaneous electronic based systems. The building blocks of these optical systems consist on waveguides and structures formed by deposited thin films. Two characteristics of utmost importance for these structures are the height and refractive index of the deposited film. In this work and by using a prism coupler, we will be presenting an optical setup and the experimental method that is used to determine both refractive index and thickness of the wave guiding structure.

ACS Style

Paulo Lourenço; Manuela Vieira; Alessandro Fantoni. Thin Film Refractive Index and Thickness. Collaboration in a Hyperconnected World 2020, 179 -188.

AMA Style

Paulo Lourenço, Manuela Vieira, Alessandro Fantoni. Thin Film Refractive Index and Thickness. Collaboration in a Hyperconnected World. 2020; ():179-188.

Chicago/Turabian Style

Paulo Lourenço; Manuela Vieira; Alessandro Fantoni. 2020. "Thin Film Refractive Index and Thickness." Collaboration in a Hyperconnected World , no. : 179-188.

Conference paper
Published: 13 April 2020 in Optical Sensing and Detection VI
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This work reports the optimisation of a plasmonic waveguide sensor based on amorphous silicon compounds (a-SiC:H, a-SiN:H or a-SiCN:H) using the FDTD method and modal decomposition. The sensor consists of an array of parallel surface plasmon interferometers with different propagation lengths, each one comprising a thin layer of metal embedded into an amorphous silicon waveguide. In order to reduce the complexity and hardware, we have proposed a structure consisting of an array of parallel surface plasmon interferometers with different propagation lengths, such that at the end of the plasmonic structure the modes can interfere constructively or destructively depending on the refractive index of the sampling medium and the propagation length. The variation of the output intensity at the end of each waveguide element provides a convenient interrogation scheme. In this work we analyse different solutions for splitting the input fundamental mode into the different parallel waveguides, including multi-mode interference structures and directional coupler splitters. By exploring amorphous silicon compounds that can be deposited by Pressure Enhanced Chemical Vapor Deposition (PECVD) at low temperatures, we aim to achieve a low-cost process that is compatible with back-end CMOS processing and wavelengths in the visible to near infrared range.

ACS Style

João Costa; Alessandro Fantoni; Paulo Lourenço; Manuela Vieira. Optimisation of a plasmonic parallel waveguide sensor based on amorphous silicon compounds. Optical Sensing and Detection VI 2020, 11354, 113542K .

AMA Style

João Costa, Alessandro Fantoni, Paulo Lourenço, Manuela Vieira. Optimisation of a plasmonic parallel waveguide sensor based on amorphous silicon compounds. Optical Sensing and Detection VI. 2020; 11354 ():113542K.

Chicago/Turabian Style

João Costa; Alessandro Fantoni; Paulo Lourenço; Manuela Vieira. 2020. "Optimisation of a plasmonic parallel waveguide sensor based on amorphous silicon compounds." Optical Sensing and Detection VI 11354, no. : 113542K.

Conference paper
Published: 02 April 2020 in Integrated Photonics Platforms: Fundamental Research, Manufacturing and Applications
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Lithographic technology has been one of the main upholders to Moore's law in the semiconductor industry for the last decades. The underlying reason that enabled the evolution in semiconductor industry has been a steady silicon wafer printing cost, while being able to dramatically increase the number of nodes that can be printed per chip. Key developments in lithography such as wavelength decreasing, together with performance increase in lens and imaging technology, should be accounted for almost all the reduction of cost per function in integrated circuits technology. In this work, we will be presenting the simulation of two mitigation techniques for the impact of defects introduced by manufacturing processes. Namely, the lithographic mask limited resolution on the geometry of the representative device. These perturbations are a consequence of the lithographic mask limited resolution on the geometry of the representative device. For this purpose, the Beam Propagation and Finite Differences Time Domain methods will be used to simulate a multimode interference structure based on silicon nitride. The structure will be affected by previously mentioned perturbations and we expect results revealing a strong dependence between mask resolution, and imbalance and power loss. Two strategies will be followed concerning the mitigation of power loss and imbalance introduced by the limited resolution of lithographic mask: - Access waveguides tapering; - Adjustable power splitting ratios through the electro-optic effect. Through both strategies we aim to achieve an improvement on device’s performance but, in the latter are expected finer tuning capabilities, being enabled by dynamic compensation of power loss and imbalance when in a closed loop control architecture.

ACS Style

Paulo Lourenço; Alessandro Fantoni; João Costa; Manuela Vieira. Silicon nitride based devices: lithographic mask roughness mitigation. Integrated Photonics Platforms: Fundamental Research, Manufacturing and Applications 2020, 11364, 113641Q .

AMA Style

Paulo Lourenço, Alessandro Fantoni, João Costa, Manuela Vieira. Silicon nitride based devices: lithographic mask roughness mitigation. Integrated Photonics Platforms: Fundamental Research, Manufacturing and Applications. 2020; 11364 ():113641Q.

Chicago/Turabian Style

Paulo Lourenço; Alessandro Fantoni; João Costa; Manuela Vieira. 2020. "Silicon nitride based devices: lithographic mask roughness mitigation." Integrated Photonics Platforms: Fundamental Research, Manufacturing and Applications 11364, no. : 113641Q.

Conference paper
Published: 01 April 2020 in Optical Sensing and Detection VI
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Optical wireless communication has been widely studied during the last years in short-range applications. This paper investigates the applicability of an intuitive wayfinding system in complex buildings using Visible Light Communication (VLC). Typical scenarios include finding places, like a particular shop or office, guiding users across different floors, through elevators and stairs. Data from the sender is encoded, modulated and converted into light signals emitted by the transmitters. Tetra-chromatic white sources are used providing a different data channel for each chip. At the receiver side, the modulated light signal, containing the ID and the 3D geographical position of the transmitter and wayfinding information, is received by SiC photodetector with light filtering and demultiplexing properties. Since lighting and wireless data communication is combined, each luminaire for downlink transmission become a single cell, in which the optical access point (AP) is located in the ceiling and the mobile users are scattered within the overlap discs of each cells underneath. The light signals emitted by the LEDs are interpreted directly by the receivers of the users positioned underneath. The effect of the location of the Aps is evaluated and a model for the different cellular networks is analyzed. Orthogonal topologies are tested, and a 3D localization design, demonstrated by a prototype implementation, is presented. Uplink transmission is implemented and the 3D best route to navigate through venue calculated. Buddy wayfinding services are also implemented. The results showed that the system make possible to determine the position of a mobile target inside the network, to infer the travel direction along the time and to interact with information received and to optimize the route towards a static or dynamic destination.

ACS Style

Manuela Vieira; Paula Louro; Alessandro Fantoni; Pedro Vieira. Indoor wayfinding using visible light communication. Optical Sensing and Detection VI 2020, 11354, 1135403 .

AMA Style

Manuela Vieira, Paula Louro, Alessandro Fantoni, Pedro Vieira. Indoor wayfinding using visible light communication. Optical Sensing and Detection VI. 2020; 11354 ():1135403.

Chicago/Turabian Style

Manuela Vieira; Paula Louro; Alessandro Fantoni; Pedro Vieira. 2020. "Indoor wayfinding using visible light communication." Optical Sensing and Detection VI 11354, no. : 1135403.

Proceedings article
Published: 05 March 2020 in Oxide-based Materials and Devices XI
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In this contribution we report on a low cost plasmonic electrode for light-sensing applications. The electrode combines a conducting nonstoichiometric indium oxide (InOx) layer with an ultrathin (~5 nm) discontinuous Au layer. The InOx and Au layers were deposited on glass substrates by plasma enhanced reactive thermal evaporation and thermal evaporation, respectively. Several device configurations with one or two Au layer(s) sandwiched between InOx layers were fabricated and characterized. The morphological and structural properties of both Au and InOx layers were analyzed using AFM and XRD techniques. In particular, the effect of thermal annealing (673 K, 15 min) on the surface morphology of Au layers grown on bare glass and InOx-coated substrate was investigated. It has been also found that the oxide film grown above an underlying nanostructured Au layer is amorphous, while a reference InOx film on glass is nanocrystalline with a smooth surface. The electrical properties of InOx grown on the Au surface are worsened due to Au-induced structural disorder. The observed difference in transmission spectra of the glass/InOx/Au and glass/Au/InOx structures indicates the difference in the morphology of the metal layer. Thus, the optical and morphological properties of the InOx electrode can be varied in a wide range by incorporating several Au layers.

ACS Style

Yuri Vygranenko; Guilherme Lavareda; Vânia André; Pedro Brogueira; Ana Amaral; Miguel Fernandes; Alessandro Fantoni; Manuela Vieira. An indium-oxide electrode with discontinuous Au layers for plasmonic devices. Oxide-based Materials and Devices XI 2020, 11281, 1128127 .

AMA Style

Yuri Vygranenko, Guilherme Lavareda, Vânia André, Pedro Brogueira, Ana Amaral, Miguel Fernandes, Alessandro Fantoni, Manuela Vieira. An indium-oxide electrode with discontinuous Au layers for plasmonic devices. Oxide-based Materials and Devices XI. 2020; 11281 ():1128127.

Chicago/Turabian Style

Yuri Vygranenko; Guilherme Lavareda; Vânia André; Pedro Brogueira; Ana Amaral; Miguel Fernandes; Alessandro Fantoni; Manuela Vieira. 2020. "An indium-oxide electrode with discontinuous Au layers for plasmonic devices." Oxide-based Materials and Devices XI 11281, no. : 1128127.

Conference paper
Published: 02 March 2020 in Physics and Simulation of Optoelectronic Devices XXVIII
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Surface Plasmon Resonance occurs when a polarized electromagnetic field strikes a metallic surface at the separation interface between metal and an insulator. This phenomenon is characterized by the conduction electrons resonant oscillation at the interface, resulting on propagating plasmon waves on the metallic surface. Since this wave is generated at the boundary between the metallic surface and the external medium, these structures are highly sensitive to alterations on the surrounding environment, namely the refractive index, and may be used in sensing structures. The large majority of these devices use noble metals, namely gold or silver, as the active material. These metals present low resistivity, which leads to low optical losses in the visible and near infrared spectrum ranges. Gold shows high environmental stability, which is essential for long-term operation, and silver’s lower stability can be overcome through the deposition of an alumina layer. However, their high cost is a limiting factor if the intended target is large scale manufacturing. In this work, we performed Finite Differences Time Domain simulations on a Surface Plasmon Resonance based sensing structure, considering cost-effective materials such as aluminium for the active metal and hydrogenated amorphous silicon for the waveguide supporting elements, and verified that these structures are able to detect refractive index variations of the surrounding environment at the 1550 μm operating wavelength. This sensing architecture has also been modelled with dispersive materials, losses included, to reflect as much as possible physical reality, revealing good performance capabilities when compared to similar noble metals based devices.

ACS Style

Paulo Lourenço; Alessandro Fantoni; Paula Louro; João Costa; Manuela Vieira. Surface plasmon resonance sensing structure. Physics and Simulation of Optoelectronic Devices XXVIII 2020, 11274, 1127415 .

AMA Style

Paulo Lourenço, Alessandro Fantoni, Paula Louro, João Costa, Manuela Vieira. Surface plasmon resonance sensing structure. Physics and Simulation of Optoelectronic Devices XXVIII. 2020; 11274 ():1127415.

Chicago/Turabian Style

Paulo Lourenço; Alessandro Fantoni; Paula Louro; João Costa; Manuela Vieira. 2020. "Surface plasmon resonance sensing structure." Physics and Simulation of Optoelectronic Devices XXVIII 11274, no. : 1127415.

Conference paper
Published: 02 March 2020 in Physics and Simulation of Optoelectronic Devices XXVIII
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Surface plasmon resonance sensors have emerged has one of the most suitable approaches for biosensing. A common approach consists of exciting the plasmons at the interface between a functionalized metal film and a sample medium containing the analyte. The propagation of the surface plasmon is highly dependent on changes of the refractive index of the surrounding environment thus providing a mechanism for sensing. The typical interrogation schemes are based on scanning over the wavelength or the incident angle to search for the resonance condition. These solutions require additional motor-driven rotation stages, prisms or other bulky components, introducing complexity which prevents the fabrication of fully on-chip devices. This work reports a simulation study of an amorphous silicon waveguide structure consisting of an array of parallel surface plasmon interferometers with different propagation lengths, each one comprising a thin layer of gold embedded into a-Si:H waveguide. The surface plasmon modes at the end of the plasmonic structure can interfere constructively or destructively depending on the refractive index of the analyte and the interferometer’s length. The variation of the output intensity at the end of each element of the array provides a convenient interrogation scheme that is suitable for on-chip integration. In this paper we investigate this setup and analyze the output power at the end of the array as a function of the refractive index of the sampling medium. The setup is simulated and characterized by the eigenmode expansion method.

ACS Style

João Costa; Alessandro Fantoni; Paulo Lourenço; Manuela Vieira. Simulation of a parallel waveguide array structure suitable for interrogation scheme in a plasmonic biosensor. Physics and Simulation of Optoelectronic Devices XXVIII 2020, 11274, 112742B .

AMA Style

João Costa, Alessandro Fantoni, Paulo Lourenço, Manuela Vieira. Simulation of a parallel waveguide array structure suitable for interrogation scheme in a plasmonic biosensor. Physics and Simulation of Optoelectronic Devices XXVIII. 2020; 11274 ():112742B.

Chicago/Turabian Style

João Costa; Alessandro Fantoni; Paulo Lourenço; Manuela Vieira. 2020. "Simulation of a parallel waveguide array structure suitable for interrogation scheme in a plasmonic biosensor." Physics and Simulation of Optoelectronic Devices XXVIII 11274, no. : 112742B.

Conference paper
Published: 02 March 2020 in Physics and Simulation of Optoelectronic Devices XXVIII
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This paper investigates the applicability of an intuitive wayfinding system in complex buildings using Visible Light Communication (VLC). Typical scenarios include: finding places, like a particular shop or office, guiding users across different floors, and through elevators and stairs. Data from the sender is encoded, modulated and converted into light signals emitted by the transmitters. Tetra-chromatic white sources are used providing a different data channel for each chip. At the receiver side, the modulated light signal, containing the ID and the 3D geographical position of the transmitter and wayfinding information, is received by a SiC photodetector with light filtering and demultiplexing properties. Since lighting and wireless data communication is combined, each luminaire for downlink transmission becomes a single cell, in which the optical access point (AP) is located in the ceiling and the mobile users are scattered across the overlap discs of each cell, underneath. The light signals emitted by the LEDs are interpreted directly by the receivers of the positioned users. Bidirectional communication is tested. The effect of the location of the Aps is evaluated and a 3D model for the cellular network is analyzed. In order to convert the floorplan to a 3D geometry, a tandem of layers in a orthogonal topology is tested, and a 3D localization design, demonstrated by a prototype implementation, is presented. Uplink transmission is implemented, and the 3D best route to navigate through venue is calculated. Buddy wayfinding services are also considered. The results showed that the dynamic VLC navigation system enables to determine the position of a mobile target inside the network, to infer the travel direction along the time, to interact with received information and to optimize the route towards a static or dynamic destination.

ACS Style

Manuela Vieira; Paula Louro; Alessandro Fantoni; Pedro Vieira. Wayfinding in complex buildings using visible light communication. Physics and Simulation of Optoelectronic Devices XXVIII 2020, 11274, 112741V .

AMA Style

Manuela Vieira, Paula Louro, Alessandro Fantoni, Pedro Vieira. Wayfinding in complex buildings using visible light communication. Physics and Simulation of Optoelectronic Devices XXVIII. 2020; 11274 ():112741V.

Chicago/Turabian Style

Manuela Vieira; Paula Louro; Alessandro Fantoni; Pedro Vieira. 2020. "Wayfinding in complex buildings using visible light communication." Physics and Simulation of Optoelectronic Devices XXVIII 11274, no. : 112741V.

Short communication
Published: 09 December 2019 in Materials Letters: X
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Graphene-based materials have been extensively explored in recent years as valuable candidates as the key material for novel structures in the field, among many other applications, of sensing devices. This work reports a study about the applicability of rGO as a support for gold nanoparticles (AuNPs) prepared with an economic and eco-friendly method using phytochemicals present in tea extract at room temperature. The overall analysis is supported by simulation results about the LSPR effect in AuNPs-rGO, obtained by Mie theory and FDTD method. The residual phytochemicals are analysed as capping agent of the nanoparticles and their influence on the LSPR properties of the nanoparticles is outlined. The resulting composite is suitable for application as a low-cost sensing layer in biomedical LSPR sensor devices.

ACS Style

Alessandro Fantoni; Vladan Stojkovic; Ana Carvalho; Ana P.C. Ribeiro; Elisabete Alegria. Characterization of AuNPs+rGO as a functionalized layer for LSPR sensors. Materials Letters: X 2019, 5, 100032 .

AMA Style

Alessandro Fantoni, Vladan Stojkovic, Ana Carvalho, Ana P.C. Ribeiro, Elisabete Alegria. Characterization of AuNPs+rGO as a functionalized layer for LSPR sensors. Materials Letters: X. 2019; 5 ():100032.

Chicago/Turabian Style

Alessandro Fantoni; Vladan Stojkovic; Ana Carvalho; Ana P.C. Ribeiro; Elisabete Alegria. 2019. "Characterization of AuNPs+rGO as a functionalized layer for LSPR sensors." Materials Letters: X 5, no. : 100032.

Journal article
Published: 09 November 2019 in Photonics
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In this paper, we present a simulation study that intends to characterize the influence of defects introduced by manufacturing processes on the geometry of a semiconductor structure suitable to be used as a multimode interference (MMI) 3 dB power splitter. Consequently, these defects will represent refractive index fluctuations which, on their turn, will drastically affect the propagation conditions within the structure. Our simulations were conducted on a software platform that implements the Beam Propagation numerical method. This work supports the development of a biomedical plasmonic sensor, which is based on the coupling between propagating modes in a dielectric waveguide and the surface plasmon mode that is generated on an overlaid metallic thin film, and where the output readout is achieved through an a-Si:H photodiode. By using a multimode interference 1 × 2 power splitter, this sensor device can utilize the non-sensing arm as a reference one, greatly facilitating its calibration and enhancing its performance. As the spectral sensitivity of amorphous silicon is restricted to the visible range, this sensing device should be operating on a wavelength not higher than 700 nm; thus, a-SiNx has been the material hereby proposed for both waveguides and MMI power splitter.

ACS Style

Paulo Lourenço; Alessandro Fantoni; João Costa; Manuela Vieira. Lithographic Mask Defects Analysis on an MMI 3 dB Splitter. Photonics 2019, 6, 118 .

AMA Style

Paulo Lourenço, Alessandro Fantoni, João Costa, Manuela Vieira. Lithographic Mask Defects Analysis on an MMI 3 dB Splitter. Photonics. 2019; 6 (4):118.

Chicago/Turabian Style

Paulo Lourenço; Alessandro Fantoni; João Costa; Manuela Vieira. 2019. "Lithographic Mask Defects Analysis on an MMI 3 dB Splitter." Photonics 6, no. 4: 118.

Conference paper
Published: 03 October 2019 in Fourth International Conference on Applications of Optics and Photonics
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In this paper, a LED-assisted positioning and navigation VLC system is proposed. A VLC scenario for large environments is stablished, the emitters and receivers are characterized and the communication protocol presented. Different layouts are analyzed. Square and hexagonal meshes are tested and a 2D localization design, demonstrated by a prototype implementation, is presented. The key differences between both topologies are discussed. For both, the transmitted information, indoor position, motion direction as well as bi-directional communication are determined. The results showed that the LED-aided VLC navigation system make possible to determine the position of a mobile target inside the network, to infer the travel direction along the time and to interact with information received.

ACS Style

Manuel Augusto Vieira; Paula Louro; Alessandro Fantoni; Pedro Vieira. Bi-directional VLC LED-assisted navigation system for large indoor environments. Fourth International Conference on Applications of Optics and Photonics 2019, 11207, 112070D .

AMA Style

Manuel Augusto Vieira, Paula Louro, Alessandro Fantoni, Pedro Vieira. Bi-directional VLC LED-assisted navigation system for large indoor environments. Fourth International Conference on Applications of Optics and Photonics. 2019; 11207 ():112070D.

Chicago/Turabian Style

Manuel Augusto Vieira; Paula Louro; Alessandro Fantoni; Pedro Vieira. 2019. "Bi-directional VLC LED-assisted navigation system for large indoor environments." Fourth International Conference on Applications of Optics and Photonics 11207, no. : 112070D.

Conference paper
Published: 03 October 2019 in Fourth International Conference on Applications of Optics and Photonics
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In this paper we present a simulation study that intends to characterize the influence of defects introduced by manufacturing processes on the geometry of a semiconductor structure suitable to be used as a multimode interference (MMI) 3 dB power splitter. Consequently, these defects will represent refractive index fluctuations which, on their turn, will drastically affect the propagation conditions within the structure. Our simulations were conducted on a software platform that implements both Beam Propagation and FDTD numerical methods. This work supports the development of a biomedical plasmonic sensor, which is based on the coupling between the propagating modes in a dielectric waveguide and the surface plasmon mode that is generated on an overlaid metallic thin film, and where the output readout is achieved through an a-Si:H photodiode. By using a multimode interference 1×2 power splitter, this sensor device can utilize the non-sensing arm as a reference one, greatly facilitating its calibration and enhanced performance. Amorphous silicon can be deposited by PECVD processes at temperatures lower than 300°C, an attractive characteristic which makes it back-end compatible to CMOS fabrication processes. As the spectral sensitivity of amorphous silicon is restricted to the visible range, this sensing device should be operating on a wavelength not higher than 700 nm, thus a- SiNx has been the material hereby proposed for both waveguides and MMI power splitter.

ACS Style

Paulo Lourenço; Alessandro Fantoni; Manuela Vieira. Simulation analysis of a thin film semiconductor MMI 3dB splitter operating in the visible range. Fourth International Conference on Applications of Optics and Photonics 2019, 11207, 112070J .

AMA Style

Paulo Lourenço, Alessandro Fantoni, Manuela Vieira. Simulation analysis of a thin film semiconductor MMI 3dB splitter operating in the visible range. Fourth International Conference on Applications of Optics and Photonics. 2019; 11207 ():112070J.

Chicago/Turabian Style

Paulo Lourenço; Alessandro Fantoni; Manuela Vieira. 2019. "Simulation analysis of a thin film semiconductor MMI 3dB splitter operating in the visible range." Fourth International Conference on Applications of Optics and Photonics 11207, no. : 112070J.

Conference paper
Published: 03 October 2019 in Fourth International Conference on Applications of Optics and Photonics
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In this work we present a simulation study about the characteristics of a semiconductor structure suitable to be used as a guided wave optical biosensor, based on Surface Plasmonic Resonance effects (SPR). The proposed structure is a planar metal-dielectric waveguide where the sensor operation is based on the coupling between the fundamental propagation TM mode and the surface plasmon excited at the outer boundary of the metal, which interfaces the sample medium. Gold and aluminum are the metals considered for the plasmonic coating, amorphous silicon and others PECVD materials are considered for the waveguide structure. The results are based on modal analysis of the waveguide and plasmonic modes. The results obtained point out the possibility of generating SPPs in the near infrared range by including a functionalized cover of reduced graphene oxide (rGO) over the metal layer.

ACS Style

Alessandro Fantoni; João Costa; Miguel Fernandes; Yuri Vygranenko; Manuela Vieira. A simulation analysis for dimensioning of an amorphous silicon planar waveguide structure suitable to be used as a surface plasmon resonance biosensor. Fourth International Conference on Applications of Optics and Photonics 2019, 11207, 112070A .

AMA Style

Alessandro Fantoni, João Costa, Miguel Fernandes, Yuri Vygranenko, Manuela Vieira. A simulation analysis for dimensioning of an amorphous silicon planar waveguide structure suitable to be used as a surface plasmon resonance biosensor. Fourth International Conference on Applications of Optics and Photonics. 2019; 11207 ():112070A.

Chicago/Turabian Style

Alessandro Fantoni; João Costa; Miguel Fernandes; Yuri Vygranenko; Manuela Vieira. 2019. "A simulation analysis for dimensioning of an amorphous silicon planar waveguide structure suitable to be used as a surface plasmon resonance biosensor." Fourth International Conference on Applications of Optics and Photonics 11207, no. : 112070A.

Conference paper
Published: 01 June 2019 in 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring)
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This work deals with the production of a low-cost disposable biosensor for point of care applications. The proposed sensor is a plasmonic structure based on the Localized Surface Plasmon Resonance (LSPR) interaction of metal nanoparticles (MNPs), embedded into a matrix of reduced Graphene Oxide (rGO). After proper functionalization with selective antibodies (Ab), the efficiency of light extinction is controlled by slight changes of the refractive coefficient induced by the concentration of biomarkers trapped by the antibodies on the sensor surface. This work reports a study about the applicability of rGO as a support for gold nanoparticles (AuNPs) for preparing the functionalized LSPR sensing layer. AuNPs are prepared with an economic and eco-friendly method using phytochemicals present in tea extract at room temperature, while a modified Hummer's method is used to synthesize rGO. The resulting AuNPs-rGO composites are studied in terms of UV-VIS spectroscopy spectral light transmission and plasmonic resonance. The overall analysis is supported by simulation results, obtained by Mie analysis, about the LSPR effect in AuNPs-rGO and its dependence on the biomarker concentration.

ACS Style

Alessandro Fantoni; Vladan Stojkovic; Miguel Fernandes; Paula Louro; Manuela Vieira; Elisabete C. B. A. Alegria; Ana P. C. Ribeiro; Ana Carvalho; Gabriela Almeida. Characterization of Plasmonic Effects in AuNP+rGO Composite as a Sensing Layer for a Low-cost Lab-on-chip Biosensor. 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) 2019, 4180 -4186.

AMA Style

Alessandro Fantoni, Vladan Stojkovic, Miguel Fernandes, Paula Louro, Manuela Vieira, Elisabete C. B. A. Alegria, Ana P. C. Ribeiro, Ana Carvalho, Gabriela Almeida. Characterization of Plasmonic Effects in AuNP+rGO Composite as a Sensing Layer for a Low-cost Lab-on-chip Biosensor. 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring). 2019; ():4180-4186.

Chicago/Turabian Style

Alessandro Fantoni; Vladan Stojkovic; Miguel Fernandes; Paula Louro; Manuela Vieira; Elisabete C. B. A. Alegria; Ana P. C. Ribeiro; Ana Carvalho; Gabriela Almeida. 2019. "Characterization of Plasmonic Effects in AuNP+rGO Composite as a Sensing Layer for a Low-cost Lab-on-chip Biosensor." 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) , no. : 4180-4186.

Conference paper
Published: 16 April 2019 in Security Education and Critical Infrastructures
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In this paper, we will be using separate software tools (wireless network and Finite Differences Time Domain based simulators) to simulate the implementation of a wireless sensor network model based on low-rate/power transmission technology. The system operates in an unlicensed frequency range and the sensing nodes rely on surface plasmon resonance phenomenon for the detection of combustion by-products. More specifically, our simulations contemplate a system for early detection of fire in densely forested areas, which will then issue a warning in an automated way. As late detection of these events usually leads to severe flora, terrain, wild life and societal impact, an early warning system will provide better event assessment conditions, thus enabling efficient resources allocation, adequate response and would certainly be a promising improvement in minimizing such disruptive impairments.

ACS Style

Paulo Lourenço; Alessandro Fantoni; Manuela Vieira. Simulation of an Early Warning Fire System. Security Education and Critical Infrastructures 2019, 305 -317.

AMA Style

Paulo Lourenço, Alessandro Fantoni, Manuela Vieira. Simulation of an Early Warning Fire System. Security Education and Critical Infrastructures. 2019; ():305-317.

Chicago/Turabian Style

Paulo Lourenço; Alessandro Fantoni; Manuela Vieira. 2019. "Simulation of an Early Warning Fire System." Security Education and Critical Infrastructures , no. : 305-317.

Conference paper
Published: 26 February 2019 in Physics and Simulation of Optoelectronic Devices XXVII
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This paper researches the applicability of an intuitive advertising system for large indoor environments using Visible Light Communication (VLC). This VLC based positioning system includes the use of the visible light signal to light the space and to transmit the information for travelers’ positioning and of advertising campaigns in the surroundings. White RGB-LEDs, whose original function is providing illumination, are used as transmitters due to the ability of each individual chip to switch quickly enough to transfer data. This functionality is used for communication where the multiplexed data can be encoded in the emitting light. The light signals emitted by the LEDs positioned in the area of the advertising campaign are interpreted directly by the customers’ receivers. A SiC optical sensor with light filtering and demultiplexing properties receives the modulated signals containing the ID and the geographical position of the LED and other information, demultiplexes and decodes the data and locates the mobile device in the environment. Different layouts are analysed: square and hexagonal meshes are tested, and a 2D localization design, demonstrated by a prototype implementation, is presented. The key differences between both topologies are discussed. For both, the transmitted information, indoor position and motion direction of the customer are determined. The results showed that the LED-aided VLC navigation system enables to determine the position of a mobile target inside the network, to infer the travel direction as a function of time and to interact with information received.

ACS Style

Manuela Vieira; Paula Louro; Alessandro Fantoni; Pedro Vieira. Indoor positioning and intuitive advertising using visible light communication. Physics and Simulation of Optoelectronic Devices XXVII 2019, 10912, 1091217 .

AMA Style

Manuela Vieira, Paula Louro, Alessandro Fantoni, Pedro Vieira. Indoor positioning and intuitive advertising using visible light communication. Physics and Simulation of Optoelectronic Devices XXVII. 2019; 10912 ():1091217.

Chicago/Turabian Style

Manuela Vieira; Paula Louro; Alessandro Fantoni; Pedro Vieira. 2019. "Indoor positioning and intuitive advertising using visible light communication." Physics and Simulation of Optoelectronic Devices XXVII 10912, no. : 1091217.

Conference paper
Published: 01 February 2019 in 2019 IEEE 6th Portuguese Meeting on Bioengineering (ENBENG)
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Graphene-based materials have been extensively explored in recent years as valuable candidates as the key material for novel structures in the field, among many other applications, of sensing devices. Reduced Graphene Oxide (rGO) is a type of chemically derived graphene, with equivalent optical properties but easier to be synthetized. This work reports a study about the applicability of rGO as a support for gold nanoparticles (AuNPs). The resulting AuNPs-rGO composites are studied in terms of spectral light transmission and plasmonic resonance as a possible sensing element for a photonic protein sensor device.

ACS Style

Alessandro Fantoni; Vladan Stojkovic; Miguel Fernandes; Manuela Vieira; Elisabete C.B.A. Alegria; Ana Paula Da Costa Ribeiro. Plasmonic properties of gold nanospheres coupled to reduced graphene oxide for biosensing applications *. 2019 IEEE 6th Portuguese Meeting on Bioengineering (ENBENG) 2019, 1 -4.

AMA Style

Alessandro Fantoni, Vladan Stojkovic, Miguel Fernandes, Manuela Vieira, Elisabete C.B.A. Alegria, Ana Paula Da Costa Ribeiro. Plasmonic properties of gold nanospheres coupled to reduced graphene oxide for biosensing applications *. 2019 IEEE 6th Portuguese Meeting on Bioengineering (ENBENG). 2019; ():1-4.

Chicago/Turabian Style

Alessandro Fantoni; Vladan Stojkovic; Miguel Fernandes; Manuela Vieira; Elisabete C.B.A. Alegria; Ana Paula Da Costa Ribeiro. 2019. "Plasmonic properties of gold nanospheres coupled to reduced graphene oxide for biosensing applications *." 2019 IEEE 6th Portuguese Meeting on Bioengineering (ENBENG) , no. : 1-4.

Journal article
Published: 20 July 2018 in Optical Engineering
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The large majority of surface plasmon resonance (SPR)-based devices use noble metals, namely gold or silver, in their manufacturing process. These metals present low resistivity, which leads to low optical losses in the visible and near-infrared spectrum ranges. Gold shows high environmental stability, which is essential for long-term operation, and the lower stability of silver can be overcome through the deposition of an alumina layer, for instance. However, their high cost is a limiting factor if the intended target is large-scale manufacturing. This work considers a cost-effective approach through the selection of aluminum as the plasmonic material and hydrogenated amorphous silicon instead of its crystalline counterpart. This SPR structure relies on Fano resonance to improve its response to refractive index deviations of the surrounding environment. Fano resonance is highly sensitive to slight changes of the medium, hence the reason we incorporated this interference phenomenon in the proposed sensing structure. We report the results obtained when conducting finite-difference time-domain algorithm-based simulations on this metal–dielectric–metal structure when the active metal is aluminum, gold, and silver. Then, we evaluate their sensitivity, detection accuracy, and resolution. The obtained results for our proposed sensing structure show good linearity and similar parameter performance as the ones obtained when using gold or silver as plasmonic materials.

ACS Style

Paulo Lourenço; Alessandro Fantoni; Miguel Fernandes; Yuri Vygranenko; Manuela Vieira. Finite-difference time-domain analysis of hydrogenated amorphous silicon and aluminum surface plasmon waveguides. Optical Engineering 2018, 57, 077103 .

AMA Style

Paulo Lourenço, Alessandro Fantoni, Miguel Fernandes, Yuri Vygranenko, Manuela Vieira. Finite-difference time-domain analysis of hydrogenated amorphous silicon and aluminum surface plasmon waveguides. Optical Engineering. 2018; 57 (7):077103.

Chicago/Turabian Style

Paulo Lourenço; Alessandro Fantoni; Miguel Fernandes; Yuri Vygranenko; Manuela Vieira. 2018. "Finite-difference time-domain analysis of hydrogenated amorphous silicon and aluminum surface plasmon waveguides." Optical Engineering 57, no. 7: 077103.