This article summarizes representative examples of elastic backscatter lidar observations in Planetary Boundary Layer (PBL) and in troposphere. The measurement objectives are the diurnal variation of the PBL stratification and cases of long-range transport of aerosol in the troposphere. Two lidars setups are used in the presented measurements. One is the traditional one, based on laser with low-repetition rate and high pulse energy, while the other setup is based on micropulse laser with high pulse repetition rate. Both lidars provide highly satisfactory results, each in its optimal measurement altitudes. The presented examples for aerosol transport include cases for Sahara dust and volcano ash. The transport studies are supported with back-trajectory analysis. The PBL studies include verification of the generally accepted processing methods for aerosol stratification determination, as well as example of diurnal development. The diurnal development of the PBL, determined by the backscatter lidar is supported with measurements with standard meteorological instruments.
{"title":"Elastic backscatter lidar in PBL study","authors":"V. Mitev","doi":"10.1117/12.2518096","DOIUrl":"https://doi.org/10.1117/12.2518096","url":null,"abstract":"This article summarizes representative examples of elastic backscatter lidar observations in Planetary Boundary Layer (PBL) and in troposphere. The measurement objectives are the diurnal variation of the PBL stratification and cases of long-range transport of aerosol in the troposphere. Two lidars setups are used in the presented measurements. One is the traditional one, based on laser with low-repetition rate and high pulse energy, while the other setup is based on micropulse laser with high pulse repetition rate. Both lidars provide highly satisfactory results, each in its optimal measurement altitudes. The presented examples for aerosol transport include cases for Sahara dust and volcano ash. The transport studies are supported with back-trajectory analysis. The PBL studies include verification of the generally accepted processing methods for aerosol stratification determination, as well as example of diurnal development. The diurnal development of the PBL, determined by the backscatter lidar is supported with measurements with standard meteorological instruments.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"81 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128649250","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Dikovska, L. Tzonev, I. Avramova, P. Terziiska, I. Bineva, G. Avdeev, E. Valcheva, J. Mladenoff, O. Angelov, S. Kolev, T. Milenov
The fabrication of nano-crystalline carbon films was implemented by the application of pulsed laser deposition (PLD) technology. The experiments were performed in a standard on-axis laser ablation (LA) configuration. The third harmonic of a Nd:YAG laser was used for ablation of a microcrystalline graphite target. All experiments were performed in vacuum at a pressure of 1×10-3 Pa for different deposition times. (001) Oriented silicon (Si) covered by either 350 or 450 nm silica (SiO2) layer was used as a substrate. The films have a thickness between 4 and 40 nm and are characterized by X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, atomic force microscopy (AFM) and ellipsometry measurements. We established deposition of nano-sized graphene-like films on top of predominantly amorphous carbon films with a thickness of 1- 2 nm. The measured the (n and k) and determined the values for the forbidden gap of the films which are between 0.01 eV and about 1 eV with reference to the sp3 hybridized carbon content of the film.
{"title":"Ellipsometric study of thin carbon films deposited by pulsed laser deposition","authors":"A. Dikovska, L. Tzonev, I. Avramova, P. Terziiska, I. Bineva, G. Avdeev, E. Valcheva, J. Mladenoff, O. Angelov, S. Kolev, T. Milenov","doi":"10.1117/12.2516970","DOIUrl":"https://doi.org/10.1117/12.2516970","url":null,"abstract":"The fabrication of nano-crystalline carbon films was implemented by the application of pulsed laser deposition (PLD) technology. The experiments were performed in a standard on-axis laser ablation (LA) configuration. The third harmonic of a Nd:YAG laser was used for ablation of a microcrystalline graphite target. All experiments were performed in vacuum at a pressure of 1×10-3 Pa for different deposition times. (001) Oriented silicon (Si) covered by either 350 or 450 nm silica (SiO2) layer was used as a substrate. The films have a thickness between 4 and 40 nm and are characterized by X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, atomic force microscopy (AFM) and ellipsometry measurements. We established deposition of nano-sized graphene-like films on top of predominantly amorphous carbon films with a thickness of 1- 2 nm. The measured the (n and k) and determined the values for the forbidden gap of the films which are between 0.01 eV and about 1 eV with reference to the sp3 hybridized carbon content of the film.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"81 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116912019","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Koleva, N. Nedyalkov, V. Nuzhdin, V. Valeev, Y. Osin, A. Stepanov
The present work concerns the fabrication and the investigation of Ag nanoparticles, surface embedded in the pulsed laser deposition (PLD) grown ZnO thin films. The third-harmonic Nd:YAG laser is used for PLD of ZnO thin films. The ion implantation technique for Ag doping in ZnO matrix is used. The morphology, texture and composition of the samples are investigated. The Ag distribution in the implanted near-surface region is investigated as a function of the processing conditions. The influence of the substrate temperature and ambient oxygen pressure during the PLD growth of ZnO films is studied. The applied processing parameters during the deposition of ZnO thin films lead to different microstructure of ZnO host matrix and have a significant impact on the properties of subsequently produced Ag/ZnO nanocomposites. The changes of optical surface plasmon resonance (SPR) band of synthesized Ag nanoparticles for different morphologies are analyzed for implanted samples. The composite nanostructures are found to exhibit SPR absorption properties of metal nanoparticles after the ion implantation, especially pronounced for the samples with laser grown ZnO matrix at high substrate temperatures. This study demonstrates how the different crystal structure of the ZnO supporting material, influences the Ag implantation process and, respectively, the properties of the produced Ag/ZnO nanocomposites.
{"title":"Synthesis and characterization of surface embedded silver nanoparticles in ZnO matrix","authors":"M. Koleva, N. Nedyalkov, V. Nuzhdin, V. Valeev, Y. Osin, A. Stepanov","doi":"10.1117/12.2516535","DOIUrl":"https://doi.org/10.1117/12.2516535","url":null,"abstract":"The present work concerns the fabrication and the investigation of Ag nanoparticles, surface embedded in the pulsed laser deposition (PLD) grown ZnO thin films. The third-harmonic Nd:YAG laser is used for PLD of ZnO thin films. The ion implantation technique for Ag doping in ZnO matrix is used. The morphology, texture and composition of the samples are investigated. The Ag distribution in the implanted near-surface region is investigated as a function of the processing conditions. The influence of the substrate temperature and ambient oxygen pressure during the PLD growth of ZnO films is studied. The applied processing parameters during the deposition of ZnO thin films lead to different microstructure of ZnO host matrix and have a significant impact on the properties of subsequently produced Ag/ZnO nanocomposites. The changes of optical surface plasmon resonance (SPR) band of synthesized Ag nanoparticles for different morphologies are analyzed for implanted samples. The composite nanostructures are found to exhibit SPR absorption properties of metal nanoparticles after the ion implantation, especially pronounced for the samples with laser grown ZnO matrix at high substrate temperatures. This study demonstrates how the different crystal structure of the ZnO supporting material, influences the Ag implantation process and, respectively, the properties of the produced Ag/ZnO nanocomposites.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"34 11","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132365262","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Bril, A. Fedarenka, V. Peshcharankou, S. Denisov, F. Asipenka, A. Slesar, M. Korol, V. Dick, Boris Chen, Leonid Sverdlik, Analoli Chaikovsky
The method of combined lidar and radiometer sounding (LRS) became a specialized tool for measuring altitude distributions of aerosol optical parameters and aerosol mode concentrations. The work gives description of advanced version of LRS technique, which integrates data of ground-based multiwavelength lidar systems, as well as satellite lidars like CALIOP, with data of AERONET radiometer stations for monitoring aerosol mode concentration profiles to study the atmospheric process over the area of large regions, or the Earth's atmosphere as a whole. Lidar and Radiometer Inversion Cod (LIRIC) is used as a base software package for processing data of terrestrial and satellite lidar observation because of high stability of its sequential inversion procedure for processing combined radiometer and lidar data. Special software module was developed to extract the ensemble of individual CALIOP profiles of attenuated backscatters in the vicinity of AERONET sites from CALIPSO Lidar L1B Profile Data. A number of collocated measurements by means of AERONET radiometer, ground-based lidar and CALIOP were carried out to validate the results of the extended LRS technique. Altitude profiles of aerosol mode concentrations retrieved from ground-based and satellite lidar data are compared to estimate differences between two types of LRSmeasurements. Advanced terrestrial and satellite LRS technique was used to obtain the “snapshot” of aerosol concentration profiles over the world in the frame of international “Lidar and Radiometer measurement campaign - 2017" (LRMC-2017). Thirty nine combined lidar and radiometer stations in Eurasian and South American continents participated in terrestrial part of the campaign.
激光雷达与辐射计探测(LRS)相结合的方法成为测量气溶胶光学参数和气溶胶模式浓度高度分布的专用工具。该工作描述了LRS技术的先进版本，该技术将地面多波长激光雷达系统以及CALIOP等卫星激光雷达的数据与AERONET辐射计站的数据相结合，用于监测气溶胶模式浓度曲线，以研究大区域或整个地球大气层的大气过程。LIRIC (Lidar and Radiometer Inversion Cod)是地面和卫星激光雷达观测数据处理的基础软件包，其处理辐射计和激光雷达数据的顺序反演程序具有很高的稳定性。开发了专门的软件模块，从CALIPSO Lidar L1B剖面数据中提取AERONET站点附近衰减后向散射的单个CALIOP剖面集合。利用AERONET辐射计、地面激光雷达和CALIOP进行了一系列同步测量，以验证扩展LRS技术的结果。比较了从地面和卫星激光雷达数据中获取的气溶胶模式浓度的高度剖面图，以估计两种lrs测量值之间的差异。在国际“激光雷达和辐射计测量运动-2017”(lrmmc -2017)框架下，采用先进的地面和卫星LRS技术获取全球气溶胶浓度曲线的“快照”。欧亚大陆和南美洲大陆的39个激光雷达和辐射计联合站参与了该运动的陆地部分。
{"title":"Implementation of synergetic observations by terrestrial and space lidar systems and sun-radiometer for study of large scale aerosol changes","authors":"A. Bril, A. Fedarenka, V. Peshcharankou, S. Denisov, F. Asipenka, A. Slesar, M. Korol, V. Dick, Boris Chen, Leonid Sverdlik, Analoli Chaikovsky","doi":"10.1117/12.2516356","DOIUrl":"https://doi.org/10.1117/12.2516356","url":null,"abstract":"The method of combined lidar and radiometer sounding (LRS) became a specialized tool for measuring altitude distributions of aerosol optical parameters and aerosol mode concentrations. The work gives description of advanced version of LRS technique, which integrates data of ground-based multiwavelength lidar systems, as well as satellite lidars like CALIOP, with data of AERONET radiometer stations for monitoring aerosol mode concentration profiles to study the atmospheric process over the area of large regions, or the Earth's atmosphere as a whole. Lidar and Radiometer Inversion Cod (LIRIC) is used as a base software package for processing data of terrestrial and satellite lidar observation because of high stability of its sequential inversion procedure for processing combined radiometer and lidar data. Special software module was developed to extract the ensemble of individual CALIOP profiles of attenuated backscatters in the vicinity of AERONET sites from CALIPSO Lidar L1B Profile Data. A number of collocated measurements by means of AERONET radiometer, ground-based lidar and CALIOP were carried out to validate the results of the extended LRS technique. Altitude profiles of aerosol mode concentrations retrieved from ground-based and satellite lidar data are compared to estimate differences between two types of LRSmeasurements. Advanced terrestrial and satellite LRS technique was used to obtain the “snapshot” of aerosol concentration profiles over the world in the frame of international “Lidar and Radiometer measurement campaign - 2017\" (LRMC-2017). Thirty nine combined lidar and radiometer stations in Eurasian and South American continents participated in terrestrial part of the campaign.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131670541","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Kasarova, N. Sultanova, Radostin Kasarov, I. Nikolov
Properties of polymeric materials are essential for their application in optical design. Refractive indices of different optical polymers are presented in the temperature diapason 10-50 °C. Dispersion is evaluated by the Abbe number at the measuring temperature. Some additional optical parameters for application in fiber optics are given. Mechanical properties of plastics are important in optical design, too. Dynamic elastic moduli of studied polymers are determined on base of ultrasonic measurements. Optomechanical, thermo-optical and thermo-mechanical parameters are presented. Application of polymeric materials in laser optical systems is illustrated by the designed all-plastic mirror objective which may be used in a lidar equipment for atmospheric pollution monitoring. Geometrical aberrations are computed.
{"title":"Properties of polymeric materials for optical systems","authors":"S. Kasarova, N. Sultanova, Radostin Kasarov, I. Nikolov","doi":"10.1117/12.2516748","DOIUrl":"https://doi.org/10.1117/12.2516748","url":null,"abstract":"Properties of polymeric materials are essential for their application in optical design. Refractive indices of different optical polymers are presented in the temperature diapason 10-50 °C. Dispersion is evaluated by the Abbe number at the measuring temperature. Some additional optical parameters for application in fiber optics are given. Mechanical properties of plastics are important in optical design, too. Dynamic elastic moduli of studied polymers are determined on base of ultrasonic measurements. Optomechanical, thermo-optical and thermo-mechanical parameters are presented. Application of polymeric materials in laser optical systems is illustrated by the designed all-plastic mirror objective which may be used in a lidar equipment for atmospheric pollution monitoring. Geometrical aberrations are computed.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114486235","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
V. N. Serkin, T. Belyaeva, G. Corro, A. Ramírez, L. Morales-Lara, R. Peña-Moreno
We review the Tappert transformation for the nonlinear Schrödinger equation and generalize it for the higher- order nonlinear Schrödinger equation (hoNLSE) model of femtosecond nonlinear optics, in which the para- meterized gravitational-like potential e¤ectively simulates the Raman self-scattering e¤ect (the soliton Raman self-frequency shift). We present the explicit gauge transformation of this model into the "free" hoNSLSE with varying in time dispersion and nonlinearity, but without external potentials. With a certain choice of the dispersion and nonlinearity parameters, hoNLSE is turning into the completely integrable physical models, for example, the Hirota equation with gravitational-like potential, for which the same reversible gauge transformation and the change of variables are fulfilled. The transformations between the proposed integrable models allowed one to obtain directly the soliton solutions of the forced nonisospectral equations - accelerating in the gravitational- like potential nonautonomous solitons - without resolving the nonisospectral IST problem with varying in time spectral parameter.
{"title":"Tappert transformation in nonlinear wave theory","authors":"V. N. Serkin, T. Belyaeva, G. Corro, A. Ramírez, L. Morales-Lara, R. Peña-Moreno","doi":"10.1117/12.2516022","DOIUrl":"https://doi.org/10.1117/12.2516022","url":null,"abstract":"We review the Tappert transformation for the nonlinear Schrödinger equation and generalize it for the higher- order nonlinear Schrödinger equation (hoNLSE) model of femtosecond nonlinear optics, in which the para- meterized gravitational-like potential e¤ectively simulates the Raman self-scattering e¤ect (the soliton Raman self-frequency shift). We present the explicit gauge transformation of this model into the \"free\" hoNSLSE with varying in time dispersion and nonlinearity, but without external potentials. With a certain choice of the dispersion and nonlinearity parameters, hoNLSE is turning into the completely integrable physical models, for example, the Hirota equation with gravitational-like potential, for which the same reversible gauge transformation and the change of variables are fulfilled. The transformations between the proposed integrable models allowed one to obtain directly the soliton solutions of the forced nonisospectral equations - accelerating in the gravitational- like potential nonautonomous solitons - without resolving the nonisospectral IST problem with varying in time spectral parameter.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"99 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121609703","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dispersion properties of photonic crystal fibers, important in many applications might differ from the desired specifications due to deficiencies in the manufacturing process, thus an experimental verification is indicated. In this paper the possibility of measuring the birefringence of a polarization-maintaining photonic crystal fiber by using an interferometric-spectral technique is demonstrated. The polarization-preserving photonic crystal fibres used belong to different manufacturers and exhibit high birefringence values, ranging from 5.7x10-4 to 6.7x10-4, when operating in the vicinity of 1550 nm. Different Sagnac interferometers were made with loops of polarization preserving fibres having different values of birefringence and length L, consequently producing diverse spectra of transmittance. A high precision optical spectrum analyzer was applied for spectral data recording, allowing to calculate the properties associated to each scheme of birefringence photonic crystal fibre. In our case, the experimentally measured values fell within the value ranges given by the manufacturers.
{"title":"Spectral interferometric measurement of a birefringence photonic crystal fiber","authors":"E. Molina Flores, A. Ramírez, A. Zehe","doi":"10.1117/12.2515429","DOIUrl":"https://doi.org/10.1117/12.2515429","url":null,"abstract":"Dispersion properties of photonic crystal fibers, important in many applications might differ from the desired specifications due to deficiencies in the manufacturing process, thus an experimental verification is indicated. In this paper the possibility of measuring the birefringence of a polarization-maintaining photonic crystal fiber by using an interferometric-spectral technique is demonstrated. The polarization-preserving photonic crystal fibres used belong to different manufacturers and exhibit high birefringence values, ranging from 5.7x10-4 to 6.7x10-4, when operating in the vicinity of 1550 nm. Different Sagnac interferometers were made with loops of polarization preserving fibres having different values of birefringence and length L, consequently producing diverse spectra of transmittance. A high precision optical spectrum analyzer was applied for spectral data recording, allowing to calculate the properties associated to each scheme of birefringence photonic crystal fibre. In our case, the experimentally measured values fell within the value ranges given by the manufacturers.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"202 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126974677","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Kaisheva, G. Bokuchava, I. Papushkin, G. Genchev, N. Doynov, R. Ossenbrink, V. Michailov, P. Petrov
This study presents an experimental results of residual stress states in stainless steel plate samples with size 100 x 50 x 10 mm welded using a high-power fiber laser. The technological parameters of the welding process were: laser power Q = 15 kW; laser spot size = 0.65 mm; welding speed V = 3 m/min; 4 m/min; 5 m/min, using 30 L/min of protective Ar gas. The neutron diffraction method was used to determine the residual stresses in the bulk of the material. The neutron experiments were performed on the FSD diffractometer at the IBR-2 pulsed reactor in the Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research - Dubna, Russian Federation. The measured residual stress distributions exhibit maxima at weld seam centers. As expected, for all specimens the residual stress is falling down in regions distant from the weld zone. Maximal residual stress value of 492 MPa was observed for sample welded with speed of V = 5 m/min.
{"title":"Determination of residual stresses in fiber laser welded stainless steel joints by neutron diffraction method","authors":"D. Kaisheva, G. Bokuchava, I. Papushkin, G. Genchev, N. Doynov, R. Ossenbrink, V. Michailov, P. Petrov","doi":"10.1117/12.2516421","DOIUrl":"https://doi.org/10.1117/12.2516421","url":null,"abstract":"This study presents an experimental results of residual stress states in stainless steel plate samples with size 100 x 50 x 10 mm welded using a high-power fiber laser. The technological parameters of the welding process were: laser power Q = 15 kW; laser spot size = 0.65 mm; welding speed V = 3 m/min; 4 m/min; 5 m/min, using 30 L/min of protective Ar gas. The neutron diffraction method was used to determine the residual stresses in the bulk of the material. The neutron experiments were performed on the FSD diffractometer at the IBR-2 pulsed reactor in the Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research - Dubna, Russian Federation. The measured residual stress distributions exhibit maxima at weld seam centers. As expected, for all specimens the residual stress is falling down in regions distant from the weld zone. Maximal residual stress value of 492 MPa was observed for sample welded with speed of V = 5 m/min.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131386987","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
C. C. Chiou, V. Marinova, S. Petrov, Cvetelina Fidanova, Cvetelina Fidanova, Ina Angelova, Ina Angelova, D. Petrova, D. Petrova, Dimitre Dimitrov, S. Lin
In this paper we demonstrate flexible polymer dispersed liquid crystal (PDLC) devices using graphene as transparent conductive electrodes on polyethylene terephthalate (PET) substrate. Graphene was grown by Low Pressure Chemical Vapor Deposition (LPCVD) technique and characterized by Raman analysis, optical and electrical measurements. Several graphene-based PDLC devices have been fabricated and their electro-optical characteristics, response time and bending ability were measured and discussed. The results support the graphene promising features for integration in flexible optoelectronics.
{"title":"Flexible and stretchable optoelectronic devices using graphene","authors":"C. C. Chiou, V. Marinova, S. Petrov, Cvetelina Fidanova, Cvetelina Fidanova, Ina Angelova, Ina Angelova, D. Petrova, D. Petrova, Dimitre Dimitrov, S. Lin","doi":"10.1117/12.2516750","DOIUrl":"https://doi.org/10.1117/12.2516750","url":null,"abstract":"In this paper we demonstrate flexible polymer dispersed liquid crystal (PDLC) devices using graphene as transparent conductive electrodes on polyethylene terephthalate (PET) substrate. Graphene was grown by Low Pressure Chemical Vapor Deposition (LPCVD) technique and characterized by Raman analysis, optical and electrical measurements. Several graphene-based PDLC devices have been fabricated and their electro-optical characteristics, response time and bending ability were measured and discussed. The results support the graphene promising features for integration in flexible optoelectronics.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114774191","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the present work, Poisson-fluctuating lidar profiles are modeled statistically as obtained from clear and hazy atmospheres containing Sharan-dust-like layers. The shot-noise fluctuations are simulated in fact induced by the useful signal itself, the optical background, and the dark current in the photon detector. The profiles obtained for UV, VIS and NIR sensing radiations are compared and analyzed. It is shown that the best lidar images of Saharan dust layers are obtainable by using NIR sensing radiation. They are characterized by higher contrast and clarity. The images obtained by using UV or VIS radiation may be entirely masked by shot-noise and even by multiple-scattering due parasitic (bias and random) noise. To clarify the images obtained in this case, by lowering the random noise level, one should average, as shown, the lidar profiles over a series of laser shots and/or smooth them along the lidar line of sight. Certainly, this lowers the temporal and/or spatial resolution of sensing by UV and VIS radiation. Thus, the results obtained confirm and illustrate the advantages of the NIR wavelength range, when sensing dense compact aerosol objects, predicted previously by the mean profiles investigated of the lidar signal strength and signal-to-noise ratio.
{"title":"Elastic-lidar signal statistics and sensing efficiency depending on the laser radiation wavelength","authors":"T. Evgenieva, V. Anguelov, L. Gurdev","doi":"10.1117/12.2516532","DOIUrl":"https://doi.org/10.1117/12.2516532","url":null,"abstract":"In the present work, Poisson-fluctuating lidar profiles are modeled statistically as obtained from clear and hazy atmospheres containing Sharan-dust-like layers. The shot-noise fluctuations are simulated in fact induced by the useful signal itself, the optical background, and the dark current in the photon detector. The profiles obtained for UV, VIS and NIR sensing radiations are compared and analyzed. It is shown that the best lidar images of Saharan dust layers are obtainable by using NIR sensing radiation. They are characterized by higher contrast and clarity. The images obtained by using UV or VIS radiation may be entirely masked by shot-noise and even by multiple-scattering due parasitic (bias and random) noise. To clarify the images obtained in this case, by lowering the random noise level, one should average, as shown, the lidar profiles over a series of laser shots and/or smooth them along the lidar line of sight. Certainly, this lowers the temporal and/or spatial resolution of sensing by UV and VIS radiation. Thus, the results obtained confirm and illustrate the advantages of the NIR wavelength range, when sensing dense compact aerosol objects, predicted previously by the mean profiles investigated of the lidar signal strength and signal-to-noise ratio.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"122 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132251838","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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