Oscar Calderon - Academia.edu (original) (raw)
Papers by Oscar Calderon
Revista Gti, 2004
Adobe recomienda que se utilice Adobe Reader o Adobe Acrobat versión 8 o posterior para trabajar ... more Adobe recomienda que se utilice Adobe Reader o Adobe Acrobat versión 8 o posterior para trabajar con los documentos del Paquete PDF. Si actualiza a la versión más reciente, disfrutará de las siguientes ventajas: • Excelente visualización de archivos PDF • Facilidad de impresión • Rapidez en las búsquedas Si no dispone de la última versión de Adobe Reader, haga clic aquí para descargar la última versión de Adobe Reader Si ya dispone de Adobe Reader 8, haga clic en un archivo del Paquete PDF para verlo.
Revista Mexicana De Ciencias Agricolas, Mar 1, 2014
Orlin Velev and co-workers report on page 4263 on the synthesis of light-diffracting assemblies o... more Orlin Velev and co-workers report on page 4263 on the synthesis of light-diffracting assemblies obtained from microspheres and nanoparticles in droplets on a superhydrophobic surface. The cover shows optical microscopy images of drying droplets from aqueous suspensions of monodisperse latex or latex/gold nanoparticle mixtures dispensed on superhydrophobic substrates. Colloidal crystals are formed in the surface layer of the droplets due to the flux of evaporating water. The colloidal crystals give rise to multicolored diffraction patterns upon illumination with collimated white light. Once completely dried, these templates yield structured nanojewel supraparticles.
Archivos latinoamericanos de nutrición, 2007
The effect of different types of probiotics present in yogurt over known populations of Staphyloc... more The effect of different types of probiotics present in yogurt over known populations of Staphylococcus aureus, Escherichia coli O157:H7, Listeria monocytogenes and Salmonella enteritidis was evaluated. The three types of yogurt used were: without added probiotics, with added probiotics (Lactobacillus casei CRL_431 and L. acidophilus CRL_730 CHR HANSEN) and another one with the same probiotics mentioned above and Lactobacillus rhamnosus (LR-35) culture. About 10(9) CFU/ mL of each potentially pathogenic bacteria was added to each type of yogurt tested, and kept in refrigeration at 4 degrees C during its shelf life, about 30 days. Bacterial count was done the initial day and every four days. Results obtained show that there is a difference in the inhibition between yogurts without added probiotics and the commercial yogurt with added probiotics; there is a clear inhibitory effect of the last one over S. aureus, E. coli O157:H7 and Listeria monocytogenes. The yogurt with added probioti...
Advanced Microsystems for Automotive Applications 2009, 2009
In this paper a study on the feasibility of a bi static radar system for bad road conditions, inc... more In this paper a study on the feasibility of a bi static radar system for bad road conditions, including water, snow and ice, is presented. First of all, the most suitable frequency is chosen among all the frequencies available for such a system from a regulatory point of view. Then, the best mathematical model for predicting the electromagnetic behaviour of
Physical Review A, 2002
We study a single-mode laser system, whose active medium consists of molecules with a large diffe... more We study a single-mode laser system, whose active medium consists of molecules with a large difference between excited and ground electrical permanent-dipole moments. In this case, the Maxwell-Bloch equations are further coupled by nonlinear terms involving the ratio between this difference between the dipoles and the transition dipole moment. It is found that these new terms lead to multiple stationary solutions. From the linear stability analysis, we demonstrate the bistable ͑or multistable͒ character of the lasing solutions.
Physical Review Special Topics - Accelerators and Beams, 2000
We present an experimental and theoretical study of the effect of desynchronism modulation on sho... more We present an experimental and theoretical study of the effect of desynchronism modulation on short pulse free-electron laser (FEL) oscillators. We find that the output power and the micropulse length of the FEL beam oscillate periodically at the modulation frequency and that the minimum micropulse length during the cycle can be significantly shorter than that which can be obtained without modulation. For example, when the desynchronism of our FEL is modulated at 40 kHz, the minimum measured micropulse length is 300 fs. Without modulation the minimum is about 700 fs. We show that when the desynchronism is modulated, the FEL can operate for part of the cycle in the normally inaccessible portion of the output power curve where the FEL gain is less than the cavity losses. It is even possible for the FEL to operate periodically in the region of negative desynchronism where gain, as normally defined, does not exist.
Advanced Photonics, 2011
Optics InfoBase is the Optical Society's online library for flagship journals, partnered... more Optics InfoBase is the Optical Society's online library for flagship journals, partnered and copublished journals, and recent proceedings from OSA conferences.
Advances in Optical Sciences Congress, 2009
We report a change in the propagation regime (subluminal-superluminal) of light pulses in a pumpe... more We report a change in the propagation regime (subluminal-superluminal) of light pulses in a pumped erbium doped fiber. We explain this behavior as a propagation effect. A pulse-width separator based on this effect is proposed.
Physical Review A, 2001
We have theoretically investigated the effects of self-phase-modulation on multiphoton nonlinear ... more We have theoretically investigated the effects of self-phase-modulation on multiphoton nonlinear optical processes in semiconductors, utilizing multiple-order perturbation theory based on a set of coupled nonlinearwave equations. Our results clearly demonstrate that the self-phase-modulation in the fundamental field induces spectral broadening in the harmonic fields ͑cross-phase modulation͒ and alleviates phase mismatch by providing a distribution of wave vectors. These results are consistent with our recent observation of extreme nonlinear optical behavior in bulk semiconductors under intense mid-infrared radiation.
Physical Review A, 2004
Pattern formation in large-aspect-ratio single-mode inhomogeneously broadened lasers is studied b... more Pattern formation in large-aspect-ratio single-mode inhomogeneously broadened lasers is studied by means of the integro-differential Maxwell-Bloch equations. As the inhomogeneous linewidth increases, the neutral stability curve shows a relaxation in the traveling wave selection allowing structures with different sizes to grow. We have performed numerical simulations with a simplified model based on a few discrete groups of atoms at different resonant frequencies to observe transverse dynamics above threshold for good and bad cavity configurations. We obtain, in general, that close to threshold the inhomogeneous broadening leads to a more complex pattern in comparison to the homogeneous broadening case. At higher pumpings, a stabilization in the number of spatial frequencies taking part in the transverse pattern is found. The influence of the laser aperture on temporal dynamics is also studied. It is shown how the typical self-pulsing regime present in single-mode inhomogeneously broadened lasers is destroyed for a wide enough aperture.
Physical Review E, 2001
Recently a new method of controlling the pulse length of a short-pulse free-electron laser ͑FEL͒ ... more Recently a new method of controlling the pulse length of a short-pulse free-electron laser ͑FEL͒ has been developed. By modulating the synchronism between the optical and electron pulses in the FEL cavity, it was found that the output power and the micropulse length of the FEL beam oscillates at the modulation frequency. In this paper, we study theoretically the behavior of the micropulse length, both in the high loss ͑steady state͒ regime and the low loss ͑limit cycle͒ regime, when a modulated desynchronism is applied. In order to do this, we analyze the dynamics of a short-pulse FEL oscillator. The modulation frequency value plays an important role in the dynamics. We find that there is a resonantlike phenomenon between the externally applied desynchronism modulation and the limit cycle oscillation without modulation of a free-electron laser.
Slow and Fast Light, 2006
How to achieve larger delays with small fiber lengths? Increasing ions concentration !! Er-doped ... more How to achieve larger delays with small fiber lengths? Increasing ions concentration !! Er-doped fibers properties 4350 8.7 x 10 25 110 ± 10 Er110 3150 6.3 x 10 25 80 ± 8 Er80 1350 2.7 x 10 25 40 ± 4 Er40 1050 2.1 x 10 25 30 ± 3 Er30 800 1.6 x 10 25 20 ± 2 Er20 Conc. (ppm) Ions dens. (m-3) Peak absorp. (dB/m) Fiber code Ions density 10-50 times greater than in Europhys. Lett. 73 (2006) L =1 m MFD @ 1550nm = 6.5 ± 0.5 µm Cladding = 125 ± 2 µm Coating = 245 ± 15 µm NA =0.2 ± 0.02
Slow and Fast Light, 2006
Control of light by light is essential in all-optical communication and optical computing. Recent... more Control of light by light is essential in all-optical communication and optical computing. Recently, there has been wide interest in the physics and applications of slow light, ie, light propagating at a very low group velocity. Con-trollably varied group velocity can make possible ...
We used scattering dichroism to study the combined effects of viscous and magnetic forces on the ... more We used scattering dichroism to study the combined effects of viscous and magnetic forces on the dynamics of dipolar chains induced in magnetorheological suspensions under rotating magnetic fields. We found that the chains adjust their size to rotate synchronously with the field but with a constant phase lag. Two different behaviors for the dichroism (proportional to the total number of aggregated particles) and the phase lag are found below or above a critical frequency. We obtained a linear dependence of the critical frequency with the square of the magnetization and with the inverse of the viscosity. The Mason number (ratio of viscous to magnetic forces) governs the dynamics. Therefore there is a critical Mason number below which, the dichroism remains almost constant and above which, the rotation of the field prevents the particle aggregation process from taken place being this the mechanism responsible for the decrease of dichroism. Our experimental results have been corroborat...
Physical Review Letters, 2011
We study slow light performance of molecular aggregates arranged in nanofilms by means of coheren... more We study slow light performance of molecular aggregates arranged in nanofilms by means of coherent population oscillations (CPO). The molecular cooperative behavior inside the aggregate enhances the delay of input signals in the GHz range in comparison with other CPO-based devices. Moreover, the problem of residual absorption present in CPO processes, is removed. We also propose an optical switch between different delays by exploiting the optical bistability of these aggregates.
Physical Review Letters, 2012
Physical Review Letters, 2004
Phase domains and phase solitons in two-level amplifying media damped by a squeezed vacuum are pr... more Phase domains and phase solitons in two-level amplifying media damped by a squeezed vacuum are predicted for the first time. Two different types of pattern formation are found depending on the relative value of the cavity detuning to the squeezed parameter: the usual one in lasers via a supercritical Hopf bifurcation and a new one via pitchfork bifurcation.
Physical Review B, 2012
We have investigated the coherent transfer of excitonic populations in a semiconductor quantum do... more We have investigated the coherent transfer of excitonic populations in a semiconductor quantum dot (SQD) modulated by the surface plasmon of a metallic nanoparticle (MNP). The SQD is considered as a three-level V-type atomic system. We applied a transform-limited laser pulse field resonant with the upper atomic levels of the SQD. When the SQD is close enough to the MNP, the otherwise equally populated atomic levels can be selectively excited. Selectivity population can be achieved by two physical mechanisms: an enhancement of the Rabi frequencies that drive the optical transitions, which depends on the polarization arrangement, and a frequency shift of the optical transitions that leads to a dynamical detuning.
Revista Gti, 2004
Adobe recomienda que se utilice Adobe Reader o Adobe Acrobat versión 8 o posterior para trabajar ... more Adobe recomienda que se utilice Adobe Reader o Adobe Acrobat versión 8 o posterior para trabajar con los documentos del Paquete PDF. Si actualiza a la versión más reciente, disfrutará de las siguientes ventajas: • Excelente visualización de archivos PDF • Facilidad de impresión • Rapidez en las búsquedas Si no dispone de la última versión de Adobe Reader, haga clic aquí para descargar la última versión de Adobe Reader Si ya dispone de Adobe Reader 8, haga clic en un archivo del Paquete PDF para verlo.
Revista Mexicana De Ciencias Agricolas, Mar 1, 2014
Orlin Velev and co-workers report on page 4263 on the synthesis of light-diffracting assemblies o... more Orlin Velev and co-workers report on page 4263 on the synthesis of light-diffracting assemblies obtained from microspheres and nanoparticles in droplets on a superhydrophobic surface. The cover shows optical microscopy images of drying droplets from aqueous suspensions of monodisperse latex or latex/gold nanoparticle mixtures dispensed on superhydrophobic substrates. Colloidal crystals are formed in the surface layer of the droplets due to the flux of evaporating water. The colloidal crystals give rise to multicolored diffraction patterns upon illumination with collimated white light. Once completely dried, these templates yield structured nanojewel supraparticles.
Archivos latinoamericanos de nutrición, 2007
The effect of different types of probiotics present in yogurt over known populations of Staphyloc... more The effect of different types of probiotics present in yogurt over known populations of Staphylococcus aureus, Escherichia coli O157:H7, Listeria monocytogenes and Salmonella enteritidis was evaluated. The three types of yogurt used were: without added probiotics, with added probiotics (Lactobacillus casei CRL_431 and L. acidophilus CRL_730 CHR HANSEN) and another one with the same probiotics mentioned above and Lactobacillus rhamnosus (LR-35) culture. About 10(9) CFU/ mL of each potentially pathogenic bacteria was added to each type of yogurt tested, and kept in refrigeration at 4 degrees C during its shelf life, about 30 days. Bacterial count was done the initial day and every four days. Results obtained show that there is a difference in the inhibition between yogurts without added probiotics and the commercial yogurt with added probiotics; there is a clear inhibitory effect of the last one over S. aureus, E. coli O157:H7 and Listeria monocytogenes. The yogurt with added probioti...
Advanced Microsystems for Automotive Applications 2009, 2009
In this paper a study on the feasibility of a bi static radar system for bad road conditions, inc... more In this paper a study on the feasibility of a bi static radar system for bad road conditions, including water, snow and ice, is presented. First of all, the most suitable frequency is chosen among all the frequencies available for such a system from a regulatory point of view. Then, the best mathematical model for predicting the electromagnetic behaviour of
Physical Review A, 2002
We study a single-mode laser system, whose active medium consists of molecules with a large diffe... more We study a single-mode laser system, whose active medium consists of molecules with a large difference between excited and ground electrical permanent-dipole moments. In this case, the Maxwell-Bloch equations are further coupled by nonlinear terms involving the ratio between this difference between the dipoles and the transition dipole moment. It is found that these new terms lead to multiple stationary solutions. From the linear stability analysis, we demonstrate the bistable ͑or multistable͒ character of the lasing solutions.
Physical Review Special Topics - Accelerators and Beams, 2000
We present an experimental and theoretical study of the effect of desynchronism modulation on sho... more We present an experimental and theoretical study of the effect of desynchronism modulation on short pulse free-electron laser (FEL) oscillators. We find that the output power and the micropulse length of the FEL beam oscillate periodically at the modulation frequency and that the minimum micropulse length during the cycle can be significantly shorter than that which can be obtained without modulation. For example, when the desynchronism of our FEL is modulated at 40 kHz, the minimum measured micropulse length is 300 fs. Without modulation the minimum is about 700 fs. We show that when the desynchronism is modulated, the FEL can operate for part of the cycle in the normally inaccessible portion of the output power curve where the FEL gain is less than the cavity losses. It is even possible for the FEL to operate periodically in the region of negative desynchronism where gain, as normally defined, does not exist.
Advanced Photonics, 2011
Optics InfoBase is the Optical Society's online library for flagship journals, partnered... more Optics InfoBase is the Optical Society's online library for flagship journals, partnered and copublished journals, and recent proceedings from OSA conferences.
Advances in Optical Sciences Congress, 2009
We report a change in the propagation regime (subluminal-superluminal) of light pulses in a pumpe... more We report a change in the propagation regime (subluminal-superluminal) of light pulses in a pumped erbium doped fiber. We explain this behavior as a propagation effect. A pulse-width separator based on this effect is proposed.
Physical Review A, 2001
We have theoretically investigated the effects of self-phase-modulation on multiphoton nonlinear ... more We have theoretically investigated the effects of self-phase-modulation on multiphoton nonlinear optical processes in semiconductors, utilizing multiple-order perturbation theory based on a set of coupled nonlinearwave equations. Our results clearly demonstrate that the self-phase-modulation in the fundamental field induces spectral broadening in the harmonic fields ͑cross-phase modulation͒ and alleviates phase mismatch by providing a distribution of wave vectors. These results are consistent with our recent observation of extreme nonlinear optical behavior in bulk semiconductors under intense mid-infrared radiation.
Physical Review A, 2004
Pattern formation in large-aspect-ratio single-mode inhomogeneously broadened lasers is studied b... more Pattern formation in large-aspect-ratio single-mode inhomogeneously broadened lasers is studied by means of the integro-differential Maxwell-Bloch equations. As the inhomogeneous linewidth increases, the neutral stability curve shows a relaxation in the traveling wave selection allowing structures with different sizes to grow. We have performed numerical simulations with a simplified model based on a few discrete groups of atoms at different resonant frequencies to observe transverse dynamics above threshold for good and bad cavity configurations. We obtain, in general, that close to threshold the inhomogeneous broadening leads to a more complex pattern in comparison to the homogeneous broadening case. At higher pumpings, a stabilization in the number of spatial frequencies taking part in the transverse pattern is found. The influence of the laser aperture on temporal dynamics is also studied. It is shown how the typical self-pulsing regime present in single-mode inhomogeneously broadened lasers is destroyed for a wide enough aperture.
Physical Review E, 2001
Recently a new method of controlling the pulse length of a short-pulse free-electron laser ͑FEL͒ ... more Recently a new method of controlling the pulse length of a short-pulse free-electron laser ͑FEL͒ has been developed. By modulating the synchronism between the optical and electron pulses in the FEL cavity, it was found that the output power and the micropulse length of the FEL beam oscillates at the modulation frequency. In this paper, we study theoretically the behavior of the micropulse length, both in the high loss ͑steady state͒ regime and the low loss ͑limit cycle͒ regime, when a modulated desynchronism is applied. In order to do this, we analyze the dynamics of a short-pulse FEL oscillator. The modulation frequency value plays an important role in the dynamics. We find that there is a resonantlike phenomenon between the externally applied desynchronism modulation and the limit cycle oscillation without modulation of a free-electron laser.
Slow and Fast Light, 2006
How to achieve larger delays with small fiber lengths? Increasing ions concentration !! Er-doped ... more How to achieve larger delays with small fiber lengths? Increasing ions concentration !! Er-doped fibers properties 4350 8.7 x 10 25 110 ± 10 Er110 3150 6.3 x 10 25 80 ± 8 Er80 1350 2.7 x 10 25 40 ± 4 Er40 1050 2.1 x 10 25 30 ± 3 Er30 800 1.6 x 10 25 20 ± 2 Er20 Conc. (ppm) Ions dens. (m-3) Peak absorp. (dB/m) Fiber code Ions density 10-50 times greater than in Europhys. Lett. 73 (2006) L =1 m MFD @ 1550nm = 6.5 ± 0.5 µm Cladding = 125 ± 2 µm Coating = 245 ± 15 µm NA =0.2 ± 0.02
Slow and Fast Light, 2006
Control of light by light is essential in all-optical communication and optical computing. Recent... more Control of light by light is essential in all-optical communication and optical computing. Recently, there has been wide interest in the physics and applications of slow light, ie, light propagating at a very low group velocity. Con-trollably varied group velocity can make possible ...
We used scattering dichroism to study the combined effects of viscous and magnetic forces on the ... more We used scattering dichroism to study the combined effects of viscous and magnetic forces on the dynamics of dipolar chains induced in magnetorheological suspensions under rotating magnetic fields. We found that the chains adjust their size to rotate synchronously with the field but with a constant phase lag. Two different behaviors for the dichroism (proportional to the total number of aggregated particles) and the phase lag are found below or above a critical frequency. We obtained a linear dependence of the critical frequency with the square of the magnetization and with the inverse of the viscosity. The Mason number (ratio of viscous to magnetic forces) governs the dynamics. Therefore there is a critical Mason number below which, the dichroism remains almost constant and above which, the rotation of the field prevents the particle aggregation process from taken place being this the mechanism responsible for the decrease of dichroism. Our experimental results have been corroborat...
Physical Review Letters, 2011
We study slow light performance of molecular aggregates arranged in nanofilms by means of coheren... more We study slow light performance of molecular aggregates arranged in nanofilms by means of coherent population oscillations (CPO). The molecular cooperative behavior inside the aggregate enhances the delay of input signals in the GHz range in comparison with other CPO-based devices. Moreover, the problem of residual absorption present in CPO processes, is removed. We also propose an optical switch between different delays by exploiting the optical bistability of these aggregates.
Physical Review Letters, 2012
Physical Review Letters, 2004
Phase domains and phase solitons in two-level amplifying media damped by a squeezed vacuum are pr... more Phase domains and phase solitons in two-level amplifying media damped by a squeezed vacuum are predicted for the first time. Two different types of pattern formation are found depending on the relative value of the cavity detuning to the squeezed parameter: the usual one in lasers via a supercritical Hopf bifurcation and a new one via pitchfork bifurcation.
Physical Review B, 2012
We have investigated the coherent transfer of excitonic populations in a semiconductor quantum do... more We have investigated the coherent transfer of excitonic populations in a semiconductor quantum dot (SQD) modulated by the surface plasmon of a metallic nanoparticle (MNP). The SQD is considered as a three-level V-type atomic system. We applied a transform-limited laser pulse field resonant with the upper atomic levels of the SQD. When the SQD is close enough to the MNP, the otherwise equally populated atomic levels can be selectively excited. Selectivity population can be achieved by two physical mechanisms: an enhancement of the Rabi frequencies that drive the optical transitions, which depends on the polarization arrangement, and a frequency shift of the optical transitions that leads to a dynamical detuning.