Proceedings of Spie the International Society For Optical Engineering, Aug 31, 2006
Three kinds of colloids containing gold nanoparticles (AuNP) were obtained by three different met... more Three kinds of colloids containing gold nanoparticles (AuNP) were obtained by three different methods of synthesis, using castor oil as dispersant agent and tetrachloroauric (III) acid as gold source. The colloidal systems were characterized by Uv-vis spectroscopy and transmission electron microscopy (TEM). Each method gave rise to quasispherical shape and different size distribution of AuNP. The TEM images of the nanostrutured systems show that from each method of synthesis, nanoparticles of different average sizes, equal to 7, 15, and 55 nm, were produced. These characteristics are reflected by the presence of different maximum wavelength absorption, indicating that each colloid presents distinct surface Plasmon resonance bands.
A large number of photonic applications have been developed based on the nonlinear optical proper... more A large number of photonic applications have been developed based on the nonlinear optical properties of materials. Different kinds of media have been studied and engineered aiming their use in photonics devices. Among the myriad of studied compounds, organic materials are of great importance due to their large optical nonlinearities and fast responses. However, a large number of organic materials have their optical properties currently uninvestigated, as ionic liquids for instance. Ionic liquids are liquid compounds that display ioniccovalent crystalline structures. They have a relatively wide electrochemically stable window, good electrical conductivity, high ionic mobility, negligible vapor pressure, and excellent chemical and thermal stability [1]. These materials are important for a large number of applications in chemistry and industry, such as catalysis, batteries, chemical analysis and as a stabilizer for colloids containing nanoparticles. An important characteristic of these materials is that some of them possess liquid crystal properties , which indicate that these compounds may present large nonlinear optical responses. In this work, we report on the first investigation of the nonlinear optical properties of two kinds of ionic liquids: 1-n-butyl-3-methylimidazolium tetrafluoroborate (BM I − BF 4 ) and 1-n-butyl-3-methylimidazolium hexafluorophosphate (BM I − P F 6 ), using the Z-scan technique. Nonlinear refraction and absorption measurements were performed for two different laser wavelengths, 514 and 810 nm, in the CW regime. The results showed that these media do not have nonlinear absorption; however they present large negative nonlinear refractive indexes, in the order of 10 −8 to 10 −9 cm 2 /W for both laser wavelengths.
The influence of the presence of barium carbonate (BaCO 3 ) phase on the luminescence properties ... more The influence of the presence of barium carbonate (BaCO 3 ) phase on the luminescence properties of barium titanate nanocrystals (BaTiO 3 ) powders was investigated. Structural and optical characterizations of erbium (Er 3+ ) doped BaTiO 3 synthesized by the sol-emulsion-gel were performed. Using Fourier transform infrared spectroscopy and X-ray powder diffraction, we identified the presence of impurities related to BaCO 3 and quantified its fraction. It was observed that the presence of BaCO 3 phase, even at low levels, depletes significantly the infrared-to-visible upconverted luminescence efficiency of the produced nanopowders.
CLEO/Europe - EQEC 2009 - European Conference on Lasers and Electro-Optics and the European Quantum Electronics Conference, 2009
Metallic nanoparticles have been intensively investigated aiming the development of more efficien... more Metallic nanoparticles have been intensively investigated aiming the development of more efficient nonlinear materials. Owing to the surface plasmon excitation and the enhancement of local field effects, metallic nanostructured solids and colloids may present large local and nonlocal nonlinear optical responses [1-3]. However, gold nanoparticles (AuNP) agglomeration in solid hosts or colloids is a drawback for their use in optical applications. Recently, we have shown that castor oil can be used as stabilizer for colloids containing AuNP . Nevertheless, there is a huge interest to develop other synthetic methods that produce stable colloids, with an effective control over the surface plasmon resonance (SPR) of AuNP.
Frontiers in Optics 2009/Laser Science XXV/Fall 2009 OSA Optics & Photonics Technical Digest, 2009
Page 1. Colloidal metallic nanoparticles in ionic liquids: new systems for nonlinear optical appl... more Page 1. Colloidal metallic nanoparticles in ionic liquids: new systems for nonlinear optical applications CEA Santos1, MARC Alencar1,*, LF Oliveira2, CW Scheeren2, J. Dupont2 and JM Hickmann1 1. Optics and Materials Group ...
Nonlinear optical properties of colloidal systems containing single wall carbon nanotubes (SWNT) ... more Nonlinear optical properties of colloidal systems containing single wall carbon nanotubes (SWNT) disperse in different surfactants are investigated. Thermal nonlinearity management Z-scan technique was performed to measure the nonlinear refractive index (n 2 ) of colloidal system. The results presented in this letter show that the presence of SWNT enhances significantly the electronic nonlinear responses of the colloid and that the surfactants play an important role in the determination of electronic part of n 2 .
Quantum Electronics and Laser Science Conference, 2001
Summary form only given. The first observation of laserlike emission from a scattering medium con... more Summary form only given. The first observation of laserlike emission from a scattering medium consisting of TiO2 particles in a dye solution was reported a few years ago. The emission from such system, which was named "laser paint" (LP) exhibits the characteristics of a multimode laser oscillator, although no resonant cavity is used. The phenomenon has been well studied but
2011 Conference on Lasers and Electro-Optics Europe and 12th European Quantum Electronics Conference (CLEO EUROPE/EQEC), 2011
Abstract Erbium-doped metaphosphate glasses were investigated as platform for optical temperature... more Abstract Erbium-doped metaphosphate glasses were investigated as platform for optical temperature sensing. The sensor is based on the fluorescence intensity ratio technique, exploiting the infrared-to-green upconversion emission of the erbium ions. Good sensing ...
Third-order nonlinear optical properties of different colloidal systems containing metallic and s... more Third-order nonlinear optical properties of different colloidal systems containing metallic and semiconducting enriched single wall carbon nanotubes have been investigated. Thermally managed Z-scan technique was performed to measure the nonlinear refractive index (n 2 ) and estimate the absorption coefficient (b) of the colloidal systems. The n 2 dispersion curve was obtained for both colloids in the range of 755-825 nm, showing a considerable increase on the nonlinear refractive index for laser tuned at 800 nm. The measurements also showed that the colloids nonlinear absorption coefficients were smaller than 8.5 · 10 À10 cm/W in this wavelength range. Analysis of the obtained figures of merit indicates that these systems are promising materials for all-optical switching applications.
Frontiers in Optics 2012/Laser Science XXVIII, 2012
ABSTRACT Information is unambiguously associated to a non analytical point in the pulse’s leading... more ABSTRACT Information is unambiguously associated to a non analytical point in the pulse’s leading edge and its propagation investigated numerically and experimentally in fast light media, leading to new unexpected effects.
3-D silica based inverse opal sample were prepared using close packed crystals of latex spheres a... more 3-D silica based inverse opal sample were prepared using close packed crystals of latex spheres as templates for silica polymerization. The samples were characterized by electron microscopy which reveals a fcc crystalline structure presenting pores with diameter of 210 nm and walls with 70 nm of thickness. The samples were infiltrated with Rhodamine 6G by soaking them in an ethanolic solution during 2 min and leaving it to dry at ambient for 2 hours. The second harmonic of a Nd:YAG laser at 532 nm (6 ns, 5 Hz) was used to excite the samples. The laser beam was focused on a region of 3 × 10-5 cm2 forming an angle of incidence of 49° with respect to, the normal of the crystal surface. The opal structure presents no absorption in the visible range but, due to the presence of dye molecules, the laser light is absorbed. The incident laser intensity was varied and the dye fluorescence was collected throughout a monochromator to monitor its characteristics.
Hybrid organic-metallic colloids consisting of Au and Ag nanoparticles dispersed in two different... more Hybrid organic-metallic colloids consisting of Au and Ag nanoparticles dispersed in two different ionic liquids were synthesized. Using the Z-scan technique, it was observed that both media presented large nonlinear optical responses owing to the thermal and the electronic contribution to the nonlinear refractive index enhanced by the presence of the metallic particles. Our results indicate that these systems are promising candidates to the development of nonlinear optical applications.
We study square and triangular optical lattice formation using a diffraction technique with light... more We study square and triangular optical lattice formation using a diffraction technique with light-possessing orbital angular momentum (OAM). We demonstrate that it is possible to use Fraunhofer diffraction of light by a square aperture to unveil OAM about two times bigger than would be possible with a triangular aperture. We notice that the pattern remains truncated until a topological charge (TC) equal to 20 with good precision. Even though a square pattern cannot be used to determine the TC sign, it is possible to measure high order of the modulus and sign of the TC up to 20, combining patterns of the triangular and square apertures.
A novel scheme for generation of laserlike emission from highly scattering media is presented. A ... more A novel scheme for generation of laserlike emission from highly scattering media is presented. A high degree of directionality is obtained owing to the excitation of surface plasmons in a silver film. The electromagnetic energy coupled to surface plasmons is transferred to a polymeric disk containing Rhodamine and TiO 2 nanospheres placed in close contact with the film. The fluorescence produced in the disk, outcoupled through a prism, displays features of a ''laser paint'' plus a high directionality.
We report the Synthesis of different CuO (ellipsoid, ribbon and sheet like) nanostructures in a s... more We report the Synthesis of different CuO (ellipsoid, ribbon and sheet like) nanostructures in a solution phase with high yield at low cost by simple reduction of aqueous solution of copper nitrate with alkaline solution of sodium hydroxide (NaOH). The morphology of the synthesized nanostructures is significantly influenced by the feeding concentration of alkaline NaOH solution. Cu(OH) 2 nanomaterials can be readily obtained by the reduction of Cu(NO 3 ) 2 solution with NaOH solution and these synthesized materials obtained at different molar concentration of NaOH solution get transformed into different nanostructures of CuO by subsequent heat treatment at 80 C for half an hour. Nanoellipsoid, nanoribbon and nanosheet like structures were obtained after heating the copper nitrate solution reduced with 0.25 M, 0.50 M, 0.75 M and 1 M concentrated NaOH solution respectively. Optical absorption spectra and corresponding band gap calculation showed that these nanomaterials have higher band gap than their bulk materials.
ABSTRACT The nonlinear optical responses of gold nanoparticles dispersed in castor oil produced b... more ABSTRACT The nonlinear optical responses of gold nanoparticles dispersed in castor oil produced by sputtering deposition were investigated, using the thermally managed Z-scan technique. Particles with spherical shape and 2.6 nm of average diameter were obtained and characterized by transmission electron microscopy and small angle X-ray scattering. This colloid was highly stable, without the presence of chemical impurities, neither stabilizers. It was observed that this system presents a large refractive third-order nonlinear response and a negligible nonlinear absorption. Moreover, the evaluation of the all-optical switching figures of merit demonstrated that the colloidal nanoparticles prepared by sputtering deposition have a good potential for the development of ultrafast photonic devices.
Proceedings of Spie the International Society For Optical Engineering, Aug 31, 2006
Three kinds of colloids containing gold nanoparticles (AuNP) were obtained by three different met... more Three kinds of colloids containing gold nanoparticles (AuNP) were obtained by three different methods of synthesis, using castor oil as dispersant agent and tetrachloroauric (III) acid as gold source. The colloidal systems were characterized by Uv-vis spectroscopy and transmission electron microscopy (TEM). Each method gave rise to quasispherical shape and different size distribution of AuNP. The TEM images of the nanostrutured systems show that from each method of synthesis, nanoparticles of different average sizes, equal to 7, 15, and 55 nm, were produced. These characteristics are reflected by the presence of different maximum wavelength absorption, indicating that each colloid presents distinct surface Plasmon resonance bands.
A large number of photonic applications have been developed based on the nonlinear optical proper... more A large number of photonic applications have been developed based on the nonlinear optical properties of materials. Different kinds of media have been studied and engineered aiming their use in photonics devices. Among the myriad of studied compounds, organic materials are of great importance due to their large optical nonlinearities and fast responses. However, a large number of organic materials have their optical properties currently uninvestigated, as ionic liquids for instance. Ionic liquids are liquid compounds that display ioniccovalent crystalline structures. They have a relatively wide electrochemically stable window, good electrical conductivity, high ionic mobility, negligible vapor pressure, and excellent chemical and thermal stability [1]. These materials are important for a large number of applications in chemistry and industry, such as catalysis, batteries, chemical analysis and as a stabilizer for colloids containing nanoparticles. An important characteristic of these materials is that some of them possess liquid crystal properties , which indicate that these compounds may present large nonlinear optical responses. In this work, we report on the first investigation of the nonlinear optical properties of two kinds of ionic liquids: 1-n-butyl-3-methylimidazolium tetrafluoroborate (BM I − BF 4 ) and 1-n-butyl-3-methylimidazolium hexafluorophosphate (BM I − P F 6 ), using the Z-scan technique. Nonlinear refraction and absorption measurements were performed for two different laser wavelengths, 514 and 810 nm, in the CW regime. The results showed that these media do not have nonlinear absorption; however they present large negative nonlinear refractive indexes, in the order of 10 −8 to 10 −9 cm 2 /W for both laser wavelengths.
The influence of the presence of barium carbonate (BaCO 3 ) phase on the luminescence properties ... more The influence of the presence of barium carbonate (BaCO 3 ) phase on the luminescence properties of barium titanate nanocrystals (BaTiO 3 ) powders was investigated. Structural and optical characterizations of erbium (Er 3+ ) doped BaTiO 3 synthesized by the sol-emulsion-gel were performed. Using Fourier transform infrared spectroscopy and X-ray powder diffraction, we identified the presence of impurities related to BaCO 3 and quantified its fraction. It was observed that the presence of BaCO 3 phase, even at low levels, depletes significantly the infrared-to-visible upconverted luminescence efficiency of the produced nanopowders.
CLEO/Europe - EQEC 2009 - European Conference on Lasers and Electro-Optics and the European Quantum Electronics Conference, 2009
Metallic nanoparticles have been intensively investigated aiming the development of more efficien... more Metallic nanoparticles have been intensively investigated aiming the development of more efficient nonlinear materials. Owing to the surface plasmon excitation and the enhancement of local field effects, metallic nanostructured solids and colloids may present large local and nonlocal nonlinear optical responses [1-3]. However, gold nanoparticles (AuNP) agglomeration in solid hosts or colloids is a drawback for their use in optical applications. Recently, we have shown that castor oil can be used as stabilizer for colloids containing AuNP . Nevertheless, there is a huge interest to develop other synthetic methods that produce stable colloids, with an effective control over the surface plasmon resonance (SPR) of AuNP.
Frontiers in Optics 2009/Laser Science XXV/Fall 2009 OSA Optics & Photonics Technical Digest, 2009
Page 1. Colloidal metallic nanoparticles in ionic liquids: new systems for nonlinear optical appl... more Page 1. Colloidal metallic nanoparticles in ionic liquids: new systems for nonlinear optical applications CEA Santos1, MARC Alencar1,*, LF Oliveira2, CW Scheeren2, J. Dupont2 and JM Hickmann1 1. Optics and Materials Group ...
Nonlinear optical properties of colloidal systems containing single wall carbon nanotubes (SWNT) ... more Nonlinear optical properties of colloidal systems containing single wall carbon nanotubes (SWNT) disperse in different surfactants are investigated. Thermal nonlinearity management Z-scan technique was performed to measure the nonlinear refractive index (n 2 ) of colloidal system. The results presented in this letter show that the presence of SWNT enhances significantly the electronic nonlinear responses of the colloid and that the surfactants play an important role in the determination of electronic part of n 2 .
Quantum Electronics and Laser Science Conference, 2001
Summary form only given. The first observation of laserlike emission from a scattering medium con... more Summary form only given. The first observation of laserlike emission from a scattering medium consisting of TiO2 particles in a dye solution was reported a few years ago. The emission from such system, which was named "laser paint" (LP) exhibits the characteristics of a multimode laser oscillator, although no resonant cavity is used. The phenomenon has been well studied but
2011 Conference on Lasers and Electro-Optics Europe and 12th European Quantum Electronics Conference (CLEO EUROPE/EQEC), 2011
Abstract Erbium-doped metaphosphate glasses were investigated as platform for optical temperature... more Abstract Erbium-doped metaphosphate glasses were investigated as platform for optical temperature sensing. The sensor is based on the fluorescence intensity ratio technique, exploiting the infrared-to-green upconversion emission of the erbium ions. Good sensing ...
Third-order nonlinear optical properties of different colloidal systems containing metallic and s... more Third-order nonlinear optical properties of different colloidal systems containing metallic and semiconducting enriched single wall carbon nanotubes have been investigated. Thermally managed Z-scan technique was performed to measure the nonlinear refractive index (n 2 ) and estimate the absorption coefficient (b) of the colloidal systems. The n 2 dispersion curve was obtained for both colloids in the range of 755-825 nm, showing a considerable increase on the nonlinear refractive index for laser tuned at 800 nm. The measurements also showed that the colloids nonlinear absorption coefficients were smaller than 8.5 · 10 À10 cm/W in this wavelength range. Analysis of the obtained figures of merit indicates that these systems are promising materials for all-optical switching applications.
Frontiers in Optics 2012/Laser Science XXVIII, 2012
ABSTRACT Information is unambiguously associated to a non analytical point in the pulse’s leading... more ABSTRACT Information is unambiguously associated to a non analytical point in the pulse’s leading edge and its propagation investigated numerically and experimentally in fast light media, leading to new unexpected effects.
3-D silica based inverse opal sample were prepared using close packed crystals of latex spheres a... more 3-D silica based inverse opal sample were prepared using close packed crystals of latex spheres as templates for silica polymerization. The samples were characterized by electron microscopy which reveals a fcc crystalline structure presenting pores with diameter of 210 nm and walls with 70 nm of thickness. The samples were infiltrated with Rhodamine 6G by soaking them in an ethanolic solution during 2 min and leaving it to dry at ambient for 2 hours. The second harmonic of a Nd:YAG laser at 532 nm (6 ns, 5 Hz) was used to excite the samples. The laser beam was focused on a region of 3 × 10-5 cm2 forming an angle of incidence of 49° with respect to, the normal of the crystal surface. The opal structure presents no absorption in the visible range but, due to the presence of dye molecules, the laser light is absorbed. The incident laser intensity was varied and the dye fluorescence was collected throughout a monochromator to monitor its characteristics.
Hybrid organic-metallic colloids consisting of Au and Ag nanoparticles dispersed in two different... more Hybrid organic-metallic colloids consisting of Au and Ag nanoparticles dispersed in two different ionic liquids were synthesized. Using the Z-scan technique, it was observed that both media presented large nonlinear optical responses owing to the thermal and the electronic contribution to the nonlinear refractive index enhanced by the presence of the metallic particles. Our results indicate that these systems are promising candidates to the development of nonlinear optical applications.
We study square and triangular optical lattice formation using a diffraction technique with light... more We study square and triangular optical lattice formation using a diffraction technique with light-possessing orbital angular momentum (OAM). We demonstrate that it is possible to use Fraunhofer diffraction of light by a square aperture to unveil OAM about two times bigger than would be possible with a triangular aperture. We notice that the pattern remains truncated until a topological charge (TC) equal to 20 with good precision. Even though a square pattern cannot be used to determine the TC sign, it is possible to measure high order of the modulus and sign of the TC up to 20, combining patterns of the triangular and square apertures.
A novel scheme for generation of laserlike emission from highly scattering media is presented. A ... more A novel scheme for generation of laserlike emission from highly scattering media is presented. A high degree of directionality is obtained owing to the excitation of surface plasmons in a silver film. The electromagnetic energy coupled to surface plasmons is transferred to a polymeric disk containing Rhodamine and TiO 2 nanospheres placed in close contact with the film. The fluorescence produced in the disk, outcoupled through a prism, displays features of a ''laser paint'' plus a high directionality.
We report the Synthesis of different CuO (ellipsoid, ribbon and sheet like) nanostructures in a s... more We report the Synthesis of different CuO (ellipsoid, ribbon and sheet like) nanostructures in a solution phase with high yield at low cost by simple reduction of aqueous solution of copper nitrate with alkaline solution of sodium hydroxide (NaOH). The morphology of the synthesized nanostructures is significantly influenced by the feeding concentration of alkaline NaOH solution. Cu(OH) 2 nanomaterials can be readily obtained by the reduction of Cu(NO 3 ) 2 solution with NaOH solution and these synthesized materials obtained at different molar concentration of NaOH solution get transformed into different nanostructures of CuO by subsequent heat treatment at 80 C for half an hour. Nanoellipsoid, nanoribbon and nanosheet like structures were obtained after heating the copper nitrate solution reduced with 0.25 M, 0.50 M, 0.75 M and 1 M concentrated NaOH solution respectively. Optical absorption spectra and corresponding band gap calculation showed that these nanomaterials have higher band gap than their bulk materials.
ABSTRACT The nonlinear optical responses of gold nanoparticles dispersed in castor oil produced b... more ABSTRACT The nonlinear optical responses of gold nanoparticles dispersed in castor oil produced by sputtering deposition were investigated, using the thermally managed Z-scan technique. Particles with spherical shape and 2.6 nm of average diameter were obtained and characterized by transmission electron microscopy and small angle X-ray scattering. This colloid was highly stable, without the presence of chemical impurities, neither stabilizers. It was observed that this system presents a large refractive third-order nonlinear response and a negligible nonlinear absorption. Moreover, the evaluation of the all-optical switching figures of merit demonstrated that the colloidal nanoparticles prepared by sputtering deposition have a good potential for the development of ultrafast photonic devices.
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