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Paulo Lourenço. Lithographic mask defects mitigation on a multimode interference structure. Optica Pura y Aplicada 2020, 53, 1 -11.
AMA StylePaulo Lourenço. Lithographic mask defects mitigation on a multimode interference structure. Optica Pura y Aplicada. 2020; 53 (3):1-11.
Chicago/Turabian StylePaulo Lourenço. 2020. "Lithographic mask defects mitigation on a multimode interference structure." Optica Pura y Aplicada 53, no. 3: 1-11.
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.
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 StyleAlessandro 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 StyleAlessandro 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.
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.
Paulo Lourenço; Manuela Vieira; Alessandro Fantoni. Thin Film Refractive Index and Thickness. Collaboration in a Hyperconnected World 2020, 179 -188.
AMA StylePaulo Lourenço, Manuela Vieira, Alessandro Fantoni. Thin Film Refractive Index and Thickness. Collaboration in a Hyperconnected World. 2020; ():179-188.
Chicago/Turabian StylePaulo Lourenço; Manuela Vieira; Alessandro Fantoni. 2020. "Thin Film Refractive Index and Thickness." Collaboration in a Hyperconnected World , no. : 179-188.
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.
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 StylePaulo 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 StylePaulo 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.
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.
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 StylePaulo 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 StylePaulo 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.
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.
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 StyleJoão 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 StyleJoão 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.
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.
Paulo Lourenço; Alessandro Fantoni; João Costa; Manuela Vieira. Lithographic Mask Defects Analysis on an MMI 3 dB Splitter. Photonics 2019, 6, 118 .
AMA StylePaulo Lourenço, Alessandro Fantoni, João Costa, Manuela Vieira. Lithographic Mask Defects Analysis on an MMI 3 dB Splitter. Photonics. 2019; 6 (4):118.
Chicago/Turabian StylePaulo Lourenço; Alessandro Fantoni; João Costa; Manuela Vieira. 2019. "Lithographic Mask Defects Analysis on an MMI 3 dB Splitter." Photonics 6, no. 4: 118.
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.
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 StylePaulo 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 StylePaulo 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.
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.
Paulo Lourenço; Alessandro Fantoni; Manuela Vieira. Simulation of an Early Warning Fire System. Security Education and Critical Infrastructures 2019, 305 -317.
AMA StylePaulo Lourenço, Alessandro Fantoni, Manuela Vieira. Simulation of an Early Warning Fire System. Security Education and Critical Infrastructures. 2019; ():305-317.
Chicago/Turabian StylePaulo Lourenço; Alessandro Fantoni; Manuela Vieira. 2019. "Simulation of an Early Warning Fire System." Security Education and Critical Infrastructures , no. : 305-317.
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.
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 StylePaulo 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 StylePaulo 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.
In this paper, we will be presenting the results obtained through Finite-Difference Time Domain simulations on a photonic sensing architecture. This device consists on a dielectric/metal/dielectric sensing structure. Under adequate conditions, when electromagnetic energy strikes the different dielectrics interface, these devices develop surface plasmon resonances which are extremely sensitive to refractive index variations, thus being able to be used as sensing structures. Considering their minute dimensions, monolithic integration is attainable and by incorporating cost-effective materials in their manufacture, devices’ mass production may be efficient and information and communication technological systems’ resiliency will be greatly facilitated. Next, this architecture is analysed under amplitude and refractive index sensitivity perspectives, its performance is analysed and considerations about its use as a sensing device are contemplated. Finally, conclusions of our work are presented and future development directions are described.
Paulo Lourenço; Manuela Vieira; Alessandro Fantoni. Simulation and Analysis of Surface Plasmon Resonance Based Sensor. Collaboration in a Hyperconnected World 2018, 252 -261.
AMA StylePaulo Lourenço, Manuela Vieira, Alessandro Fantoni. Simulation and Analysis of Surface Plasmon Resonance Based Sensor. Collaboration in a Hyperconnected World. 2018; ():252-261.
Chicago/Turabian StylePaulo Lourenço; Manuela Vieira; Alessandro Fantoni. 2018. "Simulation and Analysis of Surface Plasmon Resonance Based Sensor." Collaboration in a Hyperconnected World , no. : 252-261.
The large majority of surface plasmon resonance 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 silver’s lower stability 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. In this work, it is considered a cost-effective approach through the selection of aluminum as the plasmonic material and hydrogenated amorphous silicon instead of its crystalline counterpart. This surface plasmon resonance device 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 device. 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, and the obtained results for our proposed device show good linearity and similar parameter performance as the ones obtained when using gold or silver as plasmonic materials.
Paulo Lourenço; Alessandro Fantoni; Miguel Fernandes; Yuri Vygranenko; Manuela Vieira. FDTD analysis of Aluminum/a-Si:H surface plasmon waveguides. Physics and Simulation of Optoelectronic Devices XXVI 2018, 10526, 105262D .
AMA StylePaulo Lourenço, Alessandro Fantoni, Miguel Fernandes, Yuri Vygranenko, Manuela Vieira. FDTD analysis of Aluminum/a-Si:H surface plasmon waveguides. Physics and Simulation of Optoelectronic Devices XXVI. 2018; 10526 ():105262D.
Chicago/Turabian StylePaulo Lourenço; Alessandro Fantoni; Miguel Fernandes; Yuri Vygranenko; Manuela Vieira. 2018. "FDTD analysis of Aluminum/a-Si:H surface plasmon waveguides." Physics and Simulation of Optoelectronic Devices XXVI 10526, no. : 105262D.
Paulo Lourenco; Alessandro Fantoni; Pedro Pinho. Electromagnetic simulation of amorphous silicon waveguides. Third International Conference on Applications of Optics and Photonics 2017, 1 .
AMA StylePaulo Lourenco, Alessandro Fantoni, Pedro Pinho. Electromagnetic simulation of amorphous silicon waveguides. Third International Conference on Applications of Optics and Photonics. 2017; ():1.
Chicago/Turabian StylePaulo Lourenco; Alessandro Fantoni; Pedro Pinho. 2017. "Electromagnetic simulation of amorphous silicon waveguides." Third International Conference on Applications of Optics and Photonics , no. : 1.
This paper presents an analysis of the material quality influence for amorphous silicon waveguides for microphotonic applications. Material quality is taken into account by a model based on the absorption coefficient data obtained by Constant Photocurrent Measurement (CPM) in the near infrared region. The GUTL (Gauss-Urbach-Tauc-Lorentz) model has been presented as an extension of the standard Urbach-Tauc-Lorentz model and proposed as a predictor for the wavelength dependent optical constants of amorphous silicon in the near infrared spectra. Values produced for the GUTL model have been used as input for a set of FDTD simulations, taking in consideration different material qualities and waveguide dimensions directed to study the characteristics of amorphous silicon waveguides embedded in a SiO 2 cladding.
Alessandro Fantoni; Paulo Lourenço; M. Vieira. A model for the refractive index of amorphous silicon for FDTD simulation of photonics waveguides. 2017 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) 2017, 167 -168.
AMA StyleAlessandro Fantoni, Paulo Lourenço, M. Vieira. A model for the refractive index of amorphous silicon for FDTD simulation of photonics waveguides. 2017 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD). 2017; ():167-168.
Chicago/Turabian StyleAlessandro Fantoni; Paulo Lourenço; M. Vieira. 2017. "A model for the refractive index of amorphous silicon for FDTD simulation of photonics waveguides." 2017 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) , no. : 167-168.
Alessandro Fantoni; Paulo Lourenço; Pedro Pinho; Vieira M. FDTD simulation of amorphous silicon waveguides for microphotonics applications. Integrated Optics: Physics and Simulations III 2017, 102420U -102420U-9.
AMA StyleAlessandro Fantoni, Paulo Lourenço, Pedro Pinho, Vieira M. FDTD simulation of amorphous silicon waveguides for microphotonics applications. Integrated Optics: Physics and Simulations III. 2017; ():102420U-102420U-9.
Chicago/Turabian StyleAlessandro Fantoni; Paulo Lourenço; Pedro Pinho; Vieira M. 2017. "FDTD simulation of amorphous silicon waveguides for microphotonics applications." Integrated Optics: Physics and Simulations III , no. : 102420U-102420U-9.