Measurements of absorption coefficient and refractive index changes without the Kramers-Kronig relation in photorefractive quantum wells of GaAs

We measure the absorption coefficient and refractive index changes produced in photorefractive quantum wells of GaAs by using a high-sensitivity periodically phase-modulated two-wave mixing technique. The technique allows us to measure both the amplitude and phase of the refractive and absorption index changes simultaneously. Thus, there is no necessity to use the Kramers-Kronig relation when either the absorption or refractive index is known. We also measure the response time of the grating 2 formation in the frequency domain, yielding similar to15 mus at I-0 = 11 mW cm(-2), which shows that quantum wells of GaAs are one of the fastest materials for dynamic holography

Photoelectrochemical processes at interfaces of nanostructured TiO 2/carbon black composites studied by scanning photoelectrochemical microscopy

Pulsed photoacoustic characterization of a human skin phantom with superficial anomalies has been done with a homemade sensor. The sensor was done with a PVDF film and was used in the backward detection mode. The phantoms were agar gelatin slabs with the thickness of 100 mm and superficial anomalies were simulated by plastic spheres immersed in the slabs. The sensitivity and resolution of the sensor to measure buried anomalies it is reported. " 2008 American Institute of Physics.",,,,,,"10.1063/1.2979288",,,"http://hdl.handle.net/20.500.12104/43588","http://www.scopus.com/inward/record.url?eid=2-s2.0-52249094598&partnerID=40&md5=48882cabdb622c68b8bd3a1560cb954c",,,,,,,,"AIP Conference Proceedings",,"26

Photoacoustic characterization of human skin phantom with superficial anomalies: Preliminary results

Pulsed photoacoustic characterization of a human skin phantom with superficial anomalies has been done with a homemade sensor. The sensor was done with a PVDF film and was used in the backward detection mode. The phantoms were agar gelatin slabs with the thickness of 100 mm and superficial anomalies were simulated by plastic spheres immersed in the slabs. The sensitivity and resolution of the sensor to measure buried anomalies it is reported. © 2008 American Institute of Physics

Uniform illumination of distant targets using a spherical light-emitting diode array

The intensity of erbium up-conversion luminescence could be limited by a saturation effect due to increased pump power. We studied the luminescence saturation of the 550 nm emission on erbium-doped, SiO2TiO 2 solgel powders under pulsed excitation at 979 and 1532 nm. From the latter, the up-converted luminescence intensity decreased with increasing excitation power, whereas no saturation was observed at 979 nm excitation. We proposed that the saturation effect is determined by the pump power, the erbium content and the lifetime of the corresponding first excited states at different pumping schemes. " 2010 Elsevier B.V. All rights reserved.",,,,,,"10.1016/j.jlumin.2010.07.019",,,"http://hdl.handle.net/20.500.12104/45558","http://www.scopus.com/inward/record.url?eid=2-s2.0-77957754276&partnerID=40&md5=9a158146425d10a756ae6e614a46f488",,,,,,"12",,"Journal of Luminescence",,"235

Up-conversion luminescence saturation under pulsed excitation of erbium-doped, SiO2TiO2 solgel powders

The intensity of erbium up-conversion luminescence could be limited by a saturation effect due to increased pump power. We studied the luminescence saturation of the 550 nm emission on erbium-doped, SiO2TiO 2 solgel powders under pulsed excitation at 979 and 1532 nm. From the latter, the up-converted luminescence intensity decreased with increasing excitation power, whereas no saturation was observed at 979 nm excitation. We proposed that the saturation effect is determined by the pump power, the erbium content and the lifetime of the corresponding first excited states at different pumping schemes. © 2010 Elsevier B.V. All rights reserved

The role of local knowledge in determining shade composition of multistrata coffee systems in Chiapas, Mexico

The Ronchi test with a Liquid Crystal Display (LCD) phase grating is used for testing convergent optical systems. The rulings are computer-generated and displayed on the LCD. We prove that it is possible to make a variable electronically phase grating by using an LCD. By displaying various phase-shifted rulings and capturing the corresponding ronchigrams, the phase is obtained with the conventional phase-shifting algorithms. Experimental results are shown. " 2011 SPIE.",,,,,,"10.1117/12.889600",,,"http://hdl.handle.net/20.500.12104/45276","http://www.scopus.com/inward/record.url?eid=2-s2.0-84861074199&partnerID=40&md5=08c02155ee4adad50b6813046e5a48c2",,,,,,,,"Proceedings of SPIE - The International Society for Optical Engineering",,,,"8082",,"Scopus",,,,,,"Liquid crystal display; Nematic; Phase grating; Phase shifting; Ronchi test",,,,,,"The Ronchi test using a liquid crystal display as a phase grating",,"Conference Paper" "47039","123456789/35008",,,,"Cortés Fregoso, José Héctor",,"2002",,,,,,,,,,"0187-7674","http://hdl.handle.net/20.500.12104/45260",,,"Español",,,,"8",,"Confines de relaciones internacionales y ciencia política",,"35-42",,"14",,"CLASE",,,,,,,,"Economía del trabajo",,,,"Inversión en capital humano y segregación laboral por sexo en Guadalajara",,"journalArticle" "47074","123456789/35008",,"Benz, B.F., Inst. 'Manantlan' Ecologia C., Centro Universitario de la Costa Sur, Universidad de Guadalajara, Autlan, Jalisco Mexico C.P. 48901, Mexico; Santana M., F., Inst. 'Manantlan' Ecologia C., Centro Universitario de la Costa Sur, Universidad de Guadalajara, Autlan, Jalisco Mexico C.P. 48901, Mexico; Cevallos E., J., Inst. 'Manantlan' Ecologia C., Centro Universitario de la Costa Sur, Universidad de Guadalajara, Autlan, Jalisco Mexico C.P. 48901, Mexico; Muñoz M., E., Inst. 'Manantlan' Ecologia C., Centro Universitario de la Costa Sur, Universidad de Guadalajara, Autlan, Jalisco Mexico C.P. 48901, Mexico; Rosales A., J., Inst. 'Manantlan' Ecologia C., Centro Universitario de la Costa Sur, Universidad de Guadalajara, Autlan, Jalisco Mexico C.P. 48901, Mexico; Rosales A., M., Inst. 'Manantlan' Ecologia C., Centro Universitario de la Costa Sur, Universidad de Guadalajara, Autlan, Jalisco Mexico C.P. 48901, Mexico",,"Benz, B.F

Photocatalytic activity of erbium-doped TiO 2 nanoparticles immobilized in macro-porous silica films

A macro-porous silica film served as mechanical support to immobilize TiO 2 nanoparticles, which were doped with erbium. The films and the nanoparticles were prepared by sol-gel route. The nanoparticles exhibited photocatalytic activity under visible light. We obtained a degradation rate of methylene blue that followed first order kinetics. The sensitization of the nanoparticles to visible light was attributed to a red shift in the band-gap of the TiO 2 due to the addition of erbium ions. © 2011 Elsevier Ltd. All rights reserved

Photoluminescence of as-grown and thermal annealed SiOx/Si- nanocrystals heterolayers grown by reactive rf sputtering

A macro-porous silica film served as mechanical support to immobilize TiO 2 nanoparticles, which were doped with erbium. The films and the nanoparticles were prepared by sol-gel route. The nanoparticles exhibited photocatalytic activity under visible light. We obtained a degradation rate of methylene blue that followed first order kinetics. The sensitization of the nanoparticles to visible light was attributed to a red shift in the band-gap of the TiO 2 due to the addition of erbium ions. " 2011 Elsevier Ltd. All rights reserved.",,,,,,"10.1016/j.materresbull.2011.11.021",,,"http://hdl.handle.net/20.500.12104/43591","http://www.scopus.com/inward/record.url?eid=2-s2.0-84855689908&partnerID=40&md5=197817e694ec77c98d521d5c13da357f",,,,,,"2",,"Materials Research Bulletin",,"29