PHOTOPTICS 2020 Abstracts


Area 1 - Lasers

Full Papers
Paper Nr: 29
Title:

Evaluation of Simulator Incorporating Non-equilibrium Green’s Function and Improvement of Quantum Cascade Lasers Output using the Simulator

Authors:

Shigeyuki Takagi, Hirotaka Tanimura, Tsutomu Kakuno, Rei Hashimoto, Kei Kaneko and Shinji Saito

Abstract: We applied a simulator incorporating a non-equilibrium Green’s function (NEGF) to quantum cascade laser (QCL) wavelength prediction, and confirmed its validity including its temperature dependence. In addition, the electroluminescence (EL) intensity of the QCL was increased by a factor of 1.4 by including a structure that made the light-emitting layer barrier thin calculated using the simulator. The NEGF is used to calculate the electron density existing in the QCL and the laser gain. To examine the validity of wavelength calculation, we calculated the oscillation wavelengths for the seven types of film structure in the 3 to 9 µm band in our references, and compared them with the experimental results. As a result, the difference between them was well below 0.36 µm. Furthermore, the film structure for increasing the gain was calculated on the basis of the structure reported in one of the references. The gain was increased 1.17 to 1.28 times by reducing the thicknesses of the barriers by 10%. The QCLs with this film structure were prototyped and their EL output intensity was measured. It was confirmed that the EL output intensity output was improved and the film structure design obtained using the simulator was effective.
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Short Papers
Paper Nr: 18
Title:

Characterization Procedure of the Flight Laser Modules for the ExoMars Raman Laser Spectrometer

Authors:

Marina Benito-Parejo, Pablo Rodríguez-Pérez, Ángel Marín, José A. Rodríguez-Prieto, Rosario Canchal, Andoni Moral and Fernando Rull

Abstract: Several space missions have been sent to the surface of Mars carrying scientific instruments to study the environment. However, only one of these missions included a laser: the ChemCam instrument on-board NASA’s Curiosity mission. In 2020, two missions will be launched to study the Martian surface and search for signs of life: NASA’s Mars mission carrying SuperCam instrument that will perform Raman spectroscopy and LIBS technique; and ESA’s mission, ExoMars, with a Raman Laser Spectrometer (RLS) as part of the rover’s payload that will study the Martian surface. One of the critical points of the RLS instrument is the laser, due to the strict technological requirements that must be met to satisfy scientific and environmental requirements. This paper summarizes the electro-optical characterization campaigns that passed the Flight Model (FM) and the Flight model Spare (FS).
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Area 2 - Optics

Full Papers
Paper Nr: 9
Title:

Image Reconstruction by the Method of Convex Projections

Authors:

Tomohiro Aoyagi, Kouichi Ohtsubo and Nobuo Aoyagi

Abstract: In medical imaging modality, such as X-ray computerized tomography (CT) and positron emission tomography (PET), image reconstruction from projection is to produce an image of a two dimensional object from its line integrals along a finite number of lines. Given some subsets of a priori knowledge about the problem in Hilbert space, a formalized problem is to find the object from observed vector. If the subsets are closed and convex sets, given the convex projections onto the sets, the problem can be solved by using the method of projections onto convex sets (POCS). In this paper, we apply the method of projection onto convex sets to image reconstruction problems and evaluate the image quality in computer simulations. Also, we evaluate the influence of the noise in reconstructed image.
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Paper Nr: 11
Title:

Surface Plasmons Phase Imaging Microscopy using Deep Learning

Authors:

Suejit Pechprasarn, Suvicha Sasivimolkul, Chayanisa Sukkasem, Phitsini Suvarnaphaet and Nuntachai Thongpance

Abstract: Surface Plasmon Resonance have been a gold standard for biosensing and chemical sensing over the past decades. The surface plasmons are a confined electromagnetic wave mode propagating on surface of noble metals. One of the key features of surface plasmons is that they are sensitive to its surrounding medium, therefore the surface plasmons are usually applied in sensing applications. It has been very well established that measuring the phase response of the surface plasmons is more sensitive and more robust compared to intensity or amplitude measurements. To measure the phase, of course, an interferometer is required. This will impose the complexity to the optical alignment. Moreover, the interferometric systems usually require a well-controlled experimental condition, such as, vibration isolation system. Recently, there are some interest of the research community to recover the surface plasmons phase through computational phase retrieval algorithms, such as, Ptychography. Although these computational algorithms can recover the phase profile, they do require many images or a lengthy computing time making them not suitable for real-time measurement. Here, we propose a novel approach to perform surface plasmon phase retrieval using image recognition though deep learning. We demonstrate the feasibility of using the deep learning to recover amplitude and phase responses of simulated back focal plane images.
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Paper Nr: 14
Title:

Effect of Temperature Change on the Performance of Laser Diode at 450 nm for Submarine Optical Communications

Authors:

Chiara Lodovisi, Silvello Betti, Andrea Reale and Luigi Salamandra

Abstract: Optical communications usually require precise temperature control systems as junction temperature may dramatically influence the emission parameters of a laser diode. Recently, challenging optical applications, such as micro-satellite or underwater monitoring, need for small and low power solutions making it difficult to use complex temperature control systems. Accordingly, in this paper we explored the use of a small and passive copper heat sink to control the temperature and stabilize the transmission of GaN laser diode emitting around 450 nm. The results of a reliable thermal characterization for the various operating conditions showed the effectiveness of this simple solution.
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Paper Nr: 22
Title:

Antimonide-based Superlattice Infrared Barrier Photodetectors

Authors:

U. Zavala-Moran, R. Alchaar, J. P. Perez, J. B. Rodriguez, M. Bouschet, V. H. Compean, F. de Anda and P. Christol

Abstract: Barrier structures are now the design of high performance antimonide-based (Sb-based) cooled infrared (IR) quantum detectors. In this communication, we report on electrical and electro-optical characterizations of Ga-free and Ga-containing type-II superlattices (T2SL) photodetectors structures grown by Molecular Beam Epitaxy (MBE). Experimental measurements on Ga-free XBn and Ga-containing XBp samples were made by photo-response measurements and dark current density-voltage (J-V) characteristics performed on detectors as a function of temperature. Identification of bias voltage characteristics were extracted from measurements and resulting dark current values were compared to the state of the art of infrared technology.
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Paper Nr: 23
Title:

The Role of Plasma Kinetic Processes during High Intense THz Pulses Generation

Authors:

A.V. Bogatskaya, N. E. Gnezdovskaia and A. M. Popov

Abstract: This article is devoted to the theoretical study of THz radiation emission from plasma taking into account the kinetic properties of nonequilibrium electron velocity distribution function (EVDF) formed in the process of tunnel ionization by the two-color laser femtosecond pulse. The dispersive equation for longitudinal oscillations was solved within the framework of elementary and kinetic models of plasma volume. It was shown that the accounting of plasma kinetics can lead to essential variation of the spectral characteristics of generated pulse thus leading to a change in signal duration.
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Paper Nr: 39
Title:

Microchannels Fabricated by Laser: From the Nanosecond to the Femtosecond Pulse Duration

Authors:

María Aymerich, Javier R. Vázquez de Aldana, David Canteli, Carlos Molpeceres and M. T. Flores-Arias

Abstract: Laser technologies are used to fabricate microchannels over glass substrates. A comparison among the results obtained when these microchannels are fabricated with pulsed lasers in the three more important regime in terms of pulse duration is made. A roadmap for obtaining a similar device when different pulsed lasers are used is presented. The control on the surface roughness, a very important parameter to be taken into account when biological applications are the possible ones, is also analysed.
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Short Papers
Paper Nr: 16
Title:

High Speed Measurement in Spectral Drill using Q-plate and Camera

Authors:

Seigo Ohno, Katsuhiko Miyamoto, Shin’ichiro Hayashi and Norihiko Sekine

Abstract: We have proposed a method to scan resonance modes in a Fabry-Pérot cavity applying a geometric phase shifter, named as spectral drill. When the geometric phase shifter consists of two quarter wave plates and a half wave plate sandwiched by them is put into a cavity, the resonance modes can be scanned by the rotation of the half wave plate. Since a mechanical rotation stage has been used for scanning the cavity in our prior works, the scanning rate was limited by the rotational speed of the stage. In this work, by replacing the half wave plate to a q-plate with removing the mechanical stage and by taking transmission images by a camera, we succeeded in 720 times faster acquisition of the transmission spectrum of the spectral drill.
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Paper Nr: 19
Title:

Fabrication of Micro Spiral Phase Plates in Fused Silica using F2-Laser Microstructuring

Authors:

Sebastian Buettner, Michael Pfeifer and Steffen Weissmantel

Abstract: The results of our investigations on direct laser fabrication of micro spiral phase plates (SPPs) in fused silica using the fluorine laser microstructuring technique will be presented. The process, which based on the mask projection technique, enables the generation of SPPs with different topological charges, handedness, modulation depths and level numbers. For this, a special double mask rotation system was developed, which allows the fabrication of micro SPPs with an individual configuration with regard to the mentioned parameters. Moreover, the phase of a spherical lens can be added to the helical phase of the SPP using a special mask geometry. Furthermore, we build up a measurement system for a first optical characterization of the fabricated SPPs.
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Paper Nr: 21
Title:

Transmission of PAM4 Signals in ICXT-impaired Intra-datacenter Connections with PAM2 Signal Interference

Authors:

Inês C. Jorge, João L. Rebola and Adolfo T. Cartaxo

Abstract: Traffic in datacenters has been significantly increasing over the last few years. As a result, it is necessary to scale the connections of the datacenters to accommodate such an increase of traffic. The solution considered in this work is to use four-level pulse amplitude modulation (PAM4) and weakly-coupled multicore fibers (MCFs) to support intra-datacenter connections. However, transmission in weakly-coupled MCFs may be significantly degraded by inter-core crosstalk (ICXT). In this work, the impact of ICXT on the performance of PAM4 transmission in short-haul direct-detection links is evaluated considering two-level PAM (PAM2) signals in the interfering cores. The ICXT impact on the performance of the tested core with PAM4 transmission is evaluated using the bit error rate (BER), outage probability (OP) and eye-pattern analysis. Comparing to PAM2 transmission in the tested core, a 7.6 dB lower ICXT level is required to achieve an acceptable OP for a reference BER of 3.8×10−3 in the PAM4 link.
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Paper Nr: 31
Title:

Dielectric Relaxation and Photo-electromotive Force in Ge-Sb-Te/Si Structures

Authors:

R. A. Castro-Arata, M. A. Goryaev, A. A. Kononov, Y. Saito, P. Fons, J. Tominaga, N. I. Anisimova and A. V. Kolobov

Abstract: The dielectric properties and photovoltaic effect spectra in the compositions of amorphous layers GeSb2Te4 (GST 124), Ge2Sb2Te5 (GST 225), GeSb4Te7 (GST 147) applied on the monocrystallic silicon surface are investigated. It is shown that with a change in the GST composition, both the dielectric capacitivity and the frequency at which the maximum dielectric loss is observed change. It was found that the value of the change in photo-electromotive force is different for different layers: on samples with GST 124, the influence of amorphous layers is by an order of magnitude greater than for GST 225, and by 3 orders of magnitude greater than for GST 147.
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Paper Nr: 33
Title:

Solution Concentration and Temperature Measurements by Long-path Optical Coherence Tomography

Authors:

Tatsuo Shiina

Abstract: Long path time domain OCT was developed and applied to evaluate a certain solution under the consideration of concentration and temperature. Long path TD-OCT has the measurement range of 100mm and the resolution of position decision of 1m. Optical characteristics of the solution is represented as group refractive index by Long path TD-OCT, and it depends on solution concentration and temperature. In this study, the experimental result of the diluted alcohol solution was compared with the plural theoretical models. As a result, the measurement accuracy was confirmed with the refractive index error of less than 0.0001. Long path TD-OCT has potential to evaluate the target solution with volume, and the experiment was proceeded to monitor the spatial fluctuation process. As a result, the unique phenomenon was observed in the model experiment of partially different refractive index sample. The OCT signal had the change of knife-edge effect at the boundary of refractive index. More fundamental experiment was conducted to observe the phenomenon precisely. Now the theoretical approach was started to understand the phenomenon.
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Paper Nr: 36
Title:

A High Stroke Actuator Micro-mirror Array Designed for Adaptive Optics

Authors:

Quan Sun, Baozhu Yan and Yi Yang

Abstract: A micro-mirror with large out-of-plane displacement actuator with three polysilicon layers fabrication process is designed for adaptive optics application. The optimized micro-mirror actuating structure consists of three individual levers, each of which is actuated by electrostatic attractive force with the plane-parallel structure to produce a large upward displacement at the end of the long arm of the lever with the lever principle. Finite element analysis (FEA) models are built to calculate the maximum upward displacement of the long arm. The actuator with 320 um long arm and 80 um short arm were designed by 2um thick Poly1 layer, while the electrodes were designed by Poly0 and mirror plate was designed by Poly2 with a polish process afterwards. The micro-mirrors can be tightly arranged in a hexagonal array to be applied in adaptive optics (AO) system as a deformable mirror. An AO simulation system is built to test the aberration correction effect of the micromirror array. The results showed that the 61 micro-mirror array is better than 37 micro-mirror array in aberration correction, which showed good application prospect of this high stoke micro-mirror array in AO systems.
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Paper Nr: 4
Title:

Optimization of Coupling Efficiency of Fiber Optic Rotary Joint by Ray Tracing

Authors:

Chun-Han Chou, Rou-Jhen Chen, Hsin-Yi Tsai, Kuo-Cheng Huang and Chih-Chung Yang

Abstract: In the paper, a misalignment and field magnification tolerance analysis for the coupling efficiency of fiber optic rotary joint was presented. The analysis consisted of output position deviations from different wavelengths, dove prism manufacturing errors, light tilt and decenter errors. It helped manufacturers easily defined component specifications and assembly tolerances for fiber optic rotary joint. The 2 mm spot size was best suited for current assembly tolerances. The 2 mm beam diameter of coupling efficiency was over 80% in the tilt error ±10 arcmin and decenter error ±250 μm. In the future, we could create a FORJ system according to the simulation parameters. The practice experiment data would compare to our simulation results that used to prove our simulation results.
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Paper Nr: 10
Title:

A Study on Double-sided Optical Focusing Alignment of Transparent Substrate

Authors:

Chia-Lien Ma, Chih-Chung Yang, Yu-Hsuan Lin and Kuo-Cheng Huang

Abstract: The non-contact optical focus positioning technology proposed in this study uses the principle of optical imaging to develop a system that is simple, fast, and has a microscopic image inspection function. This study uses a dual optical path design for the upper and lower systems. The near-semi-reflective substrates in the system have different reflectivity coatings. The energy density of the transmitted and reflected light is captured through image processing. The position shift or tilt of the components is then used to calculate the energy density difference of the upper and lower systems. It can be quickly converted into focus position, system uniformity, surface height, component assembly offset and tilt. The technology of this research can overcome the problems of manual focus, additional device focus module and human eye misjudgement, and provide a measurement method and tool with simple operation and high accuracy. It can effectively adjust the Z-axis offset range of the lower system can be effectively adjusted by ±1 mm, the lower system tilts range ±1 ̊, and the substrate tilts range ±1 by the difference of the upper and lower energy densities. The Y-axis offset range is ±0.1 mm by the maximum energy density of the upper system.
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Paper Nr: 27
Title:

Raman Spectroscopy for Tumor Diagnosis in Mammary Tissue

Authors:

S. Pimenta, M. J. Maciel, A. Miranda, M. F. Cerqueira, P. Alpuim and J. H. Correia

Abstract: This paper demonstrates the potential of Raman spectroscopy in the ex-vivo analysis of resected normal and tumor mammary mouse glands, using a commercial confocal Raman microscope. The Raman spectra were acquired with a 785 nm excitation laser at 40 mW and using an integration time of 2 s. The Raman spectra for normal and tumor mouse mammary glands are presented and compared with literature results. The Raman spectrum of normal mammary mouse gland is dominated by lipid signatures. On the other hand, the Raman spectrum of tumor mammary gland is dominated by DNA and protein signatures. The molecular information obtained by using Raman spectroscopy can be fundamental for a more precise and complete diagnosis of tumors, for intraoperative assessment of tumors margins during surgeries and for tumors grade classification.
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Paper Nr: 30
Title:

Influence of Sampling Point Setting on Fitting Error of Ideal Gaussian Beam

Authors:

Yan Baozhu, Liu Wenguang, Zhou Qiong, Sun Quan and Yang Yi

Abstract: The setting of sampling points on the detector array will affect the fitting error of Gaussian beam. Based on MATLAB and least square method, the fitting of ideal Gaussian beam in one dimension and two dimensions was simulated, and the influence of sampling point interval on the fitting error of characteristic parameters, such as facula center, facula radius and center power density, were studied. The results show that, the number of sampling points in the two-dimensional simulation is greater, so the fitting accuracy is better than that in the one-dimensional simulation under the same condition of sampling point interval. In the range of initial conditions of simulation calculation, the interval of sampling points shall be d≤50mm, then the fitting error would be controlled within the range of admissible one.
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Paper Nr: 35
Title:

Homogeneous Light Source for Surface Plasmon Resonance Imaging

Authors:

Peter Hausler, Simon Jobst, Johannes Fischer, Carina Roth and Rudolf Bierl

Abstract: We describe how to build a homogeneous light source for Surface Plasmon Resonance Imaging (SPRi) which mainly finds its applications in pharmaceutical screening and biotechnology so far. SPR spectroscopy is a label-free, non-destructive and highly sensitive measurement principle for detecting changes in the refractive index in close vicinity of a gold surface. A transfer of this technology to a miniaturized sensor will broaden the range of possible applications. Commercial SPR assays are mainly working with a small number of sensing spots. In contrast, the SPR imaging system shown here will allow the use of an array of many sensing spots. In combination with chemical receptors designed as an artificial nose or an electronic tongue, the simultaneous detection of many analytes is envisioned. So far, lasers or other inhomogeneous light sources were used to illuminate the sensing surface, which is decreasing the systems sensitivity. We show a compact (< 60 mm), low cost, LED based light source which is providing a large area (>300mm2) homogeneous top hat profile. The combination of a high bit-resolution camera with our new light source enables a reflectivity based surface plasmon resonance imaging system with a high refractive index unit (RIU) resolution.
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Area 3 - Photonics

Full Papers
Paper Nr: 5
Title:

Optical Frequency Comb Generated with an Amplitude Modulated Pump in Silicon Nitride Ring-resonators

Authors:

Jose C. Boggio, Daniel Bodenmüller, S. A. Ahmed, Adnan M. Baig and Martin M. Roth

Abstract: The coherence of the repetition-rate of optical frequency combs when generated using an amplitude modulated pump is experimentally investigated. We show that the repetition-rate of the frequency comb exhibit a linewidth of ∼ 25 Hz even when the mismatch between the modulation frequency and the resonator free-spectral range is larger than the linewidth of the resonances of the ring-resonator.
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Paper Nr: 6
Title:

Interactions of Gap Solitons in Coupled Bragg Gratings with Cubic-quintic Nonlinearity and Dispersive Reflectivity

Authors:

Afroja Akter and Javid Atai

Abstract: The interaction of quiescent gap solitons in coupled fiber Bragg gratings with dispersive reflectivity and cubic-quintic nonlinearity in both cores is investigated. It has been found that with low to moderate dispersive reflectivity the interactions have similar characteristics to the nonlinear Schrodinger solitons i.e. in-phase solitons always attract each other and out-of-phase solitons repel. It is found that the interaction of in-phase solitons may result in a number of outcomes such as formation of a quiescent soliton, generation of two separating solitons and formation of a quiescent and two moving solitons. For strong dispersive reflectivity, the interaction outcomes depend on the initial separation.
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Short Papers
Paper Nr: 7
Title:

Solitons in a Dual-core System with a Uniform Bragg Grating and a Bragg Grating with Dispersive Reflectivity

Authors:

Bellal Hossain and Javid Atai

Abstract: The existence and stability of gap solitons in a dual-core optical fiber made of a uniform and a nonuniform Bragg grating with Kerr nonlinearity are considered. The nonuniformity in the one of the cores originates from the presence of dispersive reflectivity. It is found that quiescent soliton solutions exist throughout the bandgap. Stability analysis shows that there exist vast areas within the bandgap where stable solitons exist.
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Paper Nr: 12
Title:

A New View on Acousto-optic Laser Beam Combining

Authors:

Konstantin Yushkov and Vladimir Molchanov

Abstract: Coherent combining is a well-known principle of up-scaling the peak power in different types of pulsed lasers. A new type of acousto-optic beam combiner for pulsed lasers is proposed and discussed. We demonstrate that phase delay between two laser beams can be controlled and the beams can be combined using one acousto-optic device. Two cases of degenerate and non-degenerate Bragg diffraction are analyzed and compared. The experiment with anisotropic Bragg diffraction in paratellurite demonstrated efficiency of combining exceeding 95 %.
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Paper Nr: 13
Title:

Photoinactivation of Methicillin-Resistant S. Aureus Biofilm using a New Chlorin as Photosensitizer

Authors:

L. S. Amaral, I. P. Linares and J. R. Perussi

Abstract: Due to the increase in bacterial resistance to antibiotics, the development of new drugs and technologies for the eradication of microorganisms is a priority. Photodynamic Therapy (PDT) depends on the interaction between a light-sensitive compound (photosensitizer), light, and molecular oxygen. The reaction generates reactive oxygen species (ROS), which induce cell death by oxidative stress. Antimicrobial Photodynamic Therapy (A-PDT) may be a promising alternative for microbial infections since its action occurs by multiple targets, which hinders the development of resistance. The main goal of this study was the evaluation of the potential of a newly synthesized chlorin derivative sterically prevented from self-aggregation as a photosensitizer to photoinactivation Methicillin-Resistant S. aureus (MRSA) biofilm and to investigate the membrane integrity after the treatment. The results showed a high potential of this chlorin for photoinactivation of MRSA biofilms reducing the survival index more than 5 log CFU mL-1 leading to the unstructured membrane and consequent cell death by photooxidation of membrane components after A-PDT.
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Paper Nr: 28
Title:

Elements of Hybrid Opto-superconducting Convolutional Neural Networks

Authors:

A. E. Schegolev, N. V. Klenov, M. V. Tereshonok and S. S. Adjemov

Abstract: In this paper authors proposed the concepts and principals of operating of basic nonlinear elements for hybrid opto–superconducting convolutional neural network. Optical elements in computing systems are usually designed to produce only linear mathematical operations. This is insufficient for complete neural network realization on chip, where non-linear operations like activation function calculations in neuron or transfer function of rectifier linear unit are needed. We have shown the opportunity of realization of elemental base for the hybrid neural network consists of optical and superconducting parts.
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Paper Nr: 34
Title:

Cascaded Tunable Optical Delay Line based on a Racetrack Resonator with Tunable Coupling and Stable Wavelength

Authors:

Solomon G. Hailu and San-Liang Lee

Abstract: We propose a novel integrated optical delay line based on a cascaded racetrack resonator with tunable coupler by push-pull operation of each stage to stabilize the resonant wavelength. The thermal tuning effect and the photonic characteristics of the whole integrated device is simulated to verify the characteristics of the tunable ODLs. The tuning of hundreds of ps is achievable with a very compact device and very small power consumption. The two-stage configuration can allow for reaching larger delay time or a wider bandwidth depending on the operation condition.
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Paper Nr: 38
Title:

Vertical Optical Waveguide Comprising Square Base Cuboid Cores with Size Modulation for Multilayer Chip-to-Chip Interconnection

Authors:

Songpin Ran, Takaaki Kakitsuka and Kiyoto Takahata

Abstract: For chip-to-chip interconnection, a Pbit/s-class transmission capacity is expected to be developed in near future. To achieve such a huge capacity, a multilayer optical waveguide structure for connection between chips is indispensable. In this paper, a square base cuboid-core structure with size modulation for vertical light beam propagation in a polymer multilayer waveguide is proposed for improving optical coupling between the optical devices and waveguide. A 10-layer polymer waveguide with nonuniform cuboid cores are designed for single-mode transmission at 1.31 μm. Using a simulation based on the beam propagation method, it is confirmed that the proposed design can provide a coupling efficiency of −4.4 dB, which is 3.8 dB higher than that of a previously reported uniform cube-core design, for the 10-layer structure and a crosstalk of −20.6 dB. The simulated results show that the proposed nonuniform cuboid-core structure has the potential to realize a 10-layer optical waveguide structure for future chip-to-chip optical interconnection with a huge transmission capacity.
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Paper Nr: 42
Title:

Analysis of Surface Plasmon-Polariton Modes with Metallic Structures and Polarized Light across Gapped Plasmonic Waveguides

Authors:

Guhwan Kim, Sung-Ryoung Koo and Myung-Hyun Lee

Abstract: We analyzed output Surface Plasmon-Polariton (SPP) modes with gold structures in a gap when polarized light propagated across Gapped SPP Waveguides (G-SPPWs). The G-SPPWs consist of input and output insulator-metal-insulator typed SPPWs with a gap. The dielectric channel waveguide is laid across the gap. Gold was used as the metal of the SPPWs. Low loss polymers were used as the upper and lower cladding layers and the core of the dielectric channel waveguide, respectively. The input SPP mode intersects at the gap with the polarized light launched to the dielectric channel waveguide. When the TE polarized light is applied, lossy short-range SPP (SRSPP) modes are overlapped in the output SPPW. For the TM polarized light, the output SPP mode has low loss though there are mode fluctuations. When horizontal and vertical gold strips are placed in the gap and the TE polarized light is applied, the propagation loss increases significantly depending on the shape of the gold strips due to TE-induced symmetric surface charges. Inverted plasmonic signals can be generated from optical signals by the SPP modulation using excited SRSPP modes. The modulation efficiency can be increased by introducing photonic crystal or plasmonic resonance in the gap.
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Paper Nr: 44
Title:

Development of Hybrid Solar Cells based on TiO2 or ZnO-Graphene Oxide Heterojunctions

Authors:

D. Carreira, P. A. Ribeiro, M. Raposo and S. Sério

Abstract: Nowadays it is becoming increasingly necessary to find alternatives to fossil fuels in order to produce energy from renewable sources that do not have a negative impact on the environment. In this work, two types of hybrid solar cells devices were produced, in which the photoactive layer is made of poly (allylamine chloride) (PAH) and graphene oxide (GO) organic films and titanium dioxide (TiO2) or zinc oxide (ZnO) inorganic films. These films were deposited on fluoride-doped tin oxide (FTO) glass substrates, being the organic layer deposited by the layer-by-layer (LbL) technique and the inorganic layer by DC-reactive magnetron sputtering. The aluminum electrodes were deposited by thermal evaporation. The final device configuration was FTO/(PAH/GO)x/TiO2/Al and FTO/(PAH/GO)x/ZnO/Al, where x is the number of bilayers deposited. (PAH/GO)x films were characterized by ultraviolet-visible spectrophotometry, which revealed a linearity in the growth of the films with the number of bilayers. Scanning electron microscopy (SEM) showed that the morphology of the inorganic layer is homogeneous and is dependent on the number of layers of the organic layer. The SEM cross section images further revealed the desired architecture. The electrical properties were characterized by constructing current-voltage curves. The FTO/(PAH/GO)50 /TiO2/Al, FTO/(PAH/GO)30/ZnO/Al and FTO/(PAH/GO)50/ZnO/Al devices were the only ones to exhibit a diode behavior, although they did not show any reaction when exposed to light. The FTO/ (PAH/GO)50/ZnO/Al cell experienced a decrease in current when characterized in a low humidity environment, revealing that humidity is a key factor in the conduction of the organic films.
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Paper Nr: 45
Title:

Optimization of Graphene Oxide Layer-by-Layer Films to Be Used as an Enhancer Coating of Optical Fibers Sensors

Authors:

Carlota Xavier, Paulo Zagalo, Paulo A. Ribeiro and Maria Raposo

Abstract: The stability of Graphene oxide (GO) layers obtained by the layer-by-layer (LbL) films was investigated having in view the development of tunnable surfaces for optical fibre sensors in aqueous environments. For this purpose layer-by-layer (LbL) films based polyethylenimine (PEI) and GO, were prepared and characterized. The kinetics of adsorption of PEI/GO LBL films revealed that the adsorbed amount per bilayer increases linearly with the number of bilayers as expected. Furthermore adsorbed amount per bilayer for short adsorption times tends to a constant value revealing that GO layer growth also follows the adsorption behaviour expected polyelectrolytes in which electrostatic interaction is ruling the process. Finally desorption studies carried out to infer about GO layer stability revealed that GO layers are more stable at higher solutions pHs and if the adsorption time for each layer is short. These results/conclusions allowed to infer on the possible range of applications of PEI/GO LbL films.
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Paper Nr: 17
Title:

Registration Method of 3-D Laser Point Cloud Data of Snow Field

Authors:

Haiyang Zhang, Siqi Chen, Zilong Zhang and Changming Zhao

Abstract: Laser point cloud registration is a crucial part of 3D reconstruction. The laser scanning of snow field is prone to noise and the lack of point cloud data leads to poor registration accuracy of point cloud. The optimized particle swarm optimization algorithm must be used to find the optimal spatial transformation matrix point cloud coarse registration method with point cloud distribution entropy as the optimal target, which provides good initial conditions for point cloud fine registration. Through simulation verification, it is proved that the point cloud entropy has faster calculation speed than the traditional mean squared difference evaluation method. The Particle Swarm Optimization based on Beetle Antennae Search Algorithm has the characteristics of strong global search ability and fast calculation speed. It shows better robustness under conditions of noise and missing data.