CdSe nanoplatelets(NPLs)are promising candidates for on-chip light sources,yet their performance is hindered by surface defects and inefficient optical gain.Herein,we demonstrate that CdSeS crown passivation significa...CdSe nanoplatelets(NPLs)are promising candidates for on-chip light sources,yet their performance is hindered by surface defects and inefficient optical gain.Herein,we demonstrate that CdSeS crown passivation significantly enhances the photophysical property of CdSe NPLs.Laser spectroscopy techniques reveal suppressed electronic and hole trapping at lateral surfaces,leading to a 4.2-fold increase in photoluminescence quantum yield and a shortened emission lifetime from13.5 to 4.8 ns.In addition,amplified spontaneous emission is achieved under nanosecond pulse pumping,with thresholds of0.75 to 0.16 mJ/cm^(2)for CdSe and CdSe/CdSeS NPLs,respectively.By integrating CdSe/CdSeS NPLs with high-refractiveindex SiO2scatters,coherent random lasing is realized at a threshold of 0.21 mJ/cm^(2).These findings highlight the critical role of lateral surface passivation in optimizing optical gain and pave the way for low-cost,multifunctional nanophotonic devices.展开更多
In this paper,we investigate the bichromatic coherent random lasing actions from the dye-doped polymer stabilized blue phase liquid crystals.Two groups of lasing peaks,of which the full widith at half maximum is about...In this paper,we investigate the bichromatic coherent random lasing actions from the dye-doped polymer stabilized blue phase liquid crystals.Two groups of lasing peaks,of which the full widith at half maximum is about 0.3 nm,are clearly observed.The shorter-and longer-wavelength modes are associated with the excitation of the single laser dye（DCM） monomers and dimers respectively.The experimental results show that the competition between the two groups of the lasing peaks can be controlled by varying the polarization of the pump light.When the polarization of the pump light is rotated from 0？to 90？,the intensity of the shorter-wavelength lasing peak group reduces while the intensity of the longer-wavelength lasing peak group increases.In addition,a red shift of the longer-wavelength modes is also observed and the physical mechanisms behind the red-shift phenomenon are discussed.展开更多
A dye-doped polymer-dispersed liquid crystal film was designed and fabricated,and random lasing action was studied.A mixture of laser dye,nematic liquid crystal,chiral dopant,and PVA was used to prepare the dye-doped ...A dye-doped polymer-dispersed liquid crystal film was designed and fabricated,and random lasing action was studied.A mixture of laser dye,nematic liquid crystal,chiral dopant,and PVA was used to prepare the dye-doped polymer-dispersed liquid crystal film by means of microcapsules.Scanning electron microscopy analysis showed that most liquid crystal droplets in the polymer matrix ranged from 30 μm to 40 μm,the size of the liquid crystal droplets was small.Under frequency doubled 532 nm Nd：YAG laser-pumped optical excitation,a plurality of discrete and sharp random laser radiation peaks could be measured in the range of 575–590 nm.The line-width of the lasing peak was 0.2 nm and the threshold of the random lasing was 9 m J.Under heating,the emission peaks of random lasing disappeared.By detecting the emission light spot energy distribution,the mechanism of radiation was found to be random lasing.The random lasing radiation mechanism was then analyzed and discussed.Experimental results indicated that the size of the liquid crystal droplets is the decisive factor that influences the lasing mechanism.The surface anchor role can be ignored when the size of the liquid crystal droplets in the polymer matrix is small,which is beneficial to form multiple scattering.The transmission path of photons is similar to that in a ring cavity,providing feedback to obtain random lasing output.展开更多
A directional random laser mediated by transverse Anderson localization in a disordered glass optical fiber is reported.Previous demonstrations of random lasers have found limited applications because of their multi-d...A directional random laser mediated by transverse Anderson localization in a disordered glass optical fiber is reported.Previous demonstrations of random lasers have found limited applications because of their multi-directionality and chaotic fluctuations in the laser emission.The random laser presented in this paper operates in the Anderson localization regime.The disorder induced localized states form isolated local channels that make the output laser beam highly directional and stabilize its spectrum.The strong transverse disorder and longitudinal invariance result in isolated lasing modes with negligible interaction with their surroundings,traveling back and forth in a Fabry–Perot cavity formed by the air–fiber interfaces.It is shown that if a localized input pump is scanned across the disordered fiber input facet,the output laser signal follows the transverse position of the pump.Moreover,a uniformly distributed pump across the input facet of the disordered fiber generates a laser signal with very low spatial coherence that can be of practical importance in many optical platforms including image transport with fiber bundles.展开更多
Optoelectronic nanocomposites are a new class of materials, which exhibit very interesting and particular properties and attract a growing attention due to their potential applications in information storage and optoe...Optoelectronic nanocomposites are a new class of materials, which exhibit very interesting and particular properties and attract a growing attention due to their potential applications in information storage and optoelectronic devices. Zinc oxide, ZnO, is one of the most interesting binary semiconductor （3.37 eV） with very important optical properties, which can be used in the fields such as short wavelength lasers, blue light emitting diodes, UV detectors, gas sensors, etc. This paper reviews the very recent progress in the prepa- ration of silica-based ZnO nanocomposites. After an introduction reviewing the theoretical background, the article will begin with a survey of the optical properties and the quantum size effect （QSE） of ZnO/SiO2 nanocomposites prepared by the inclusion of ZnO nanoclusters inside silica mesoporous materials. The second part will focus on one of the most interesting properties of ZnO/SiO2 nanocomposites, which is the random lasing effect after one- and two-photon excitation. The final part will deal with the introduction of ZnO nanoparticles inside microporous zeolites and the observation of QSE. For comparison, the photoluminescence （PL） and QSE properties of ZnS nanoparticles occluded in mesoporous media are also described. New potential applications will be discussed since short-wavelength devices are required by industry to design, for instance, new information storage supports and biolabelling devices.展开更多
Laser-based light sources are highly desirable for display applications due to their narrow emission linewidth and exceptional brightness.However,the coherence inherent in lasers often leads to the formation of unwant...Laser-based light sources are highly desirable for display applications due to their narrow emission linewidth and exceptional brightness.However,the coherence inherent in lasers often leads to the formation of unwanted speckles,which can significantly degrade display quality.Thus,there is a critical need for light sources that retain the narrow emission and high brightness of lasers while minimizing spatial coherence to reduce speckle formation.Random lasing has emerged as a promising strategy to address this issue,though its random emission directions can lead to energy losses.To overcome this challenge,we propose a novel approach in which CdSe nanoplatelets,known for their efficient optical gain properties,are self-assembled into supraparticles(SPs),serving as both scattering centers and gain media.This configuration enables random lasing,and by coupling the random gain medium to a Fabry-Perot(FP)cavity,we successfully direct the typically omnidirectional random lasing into a controlled,low-coherence emission.Our experimental results,comparing conventional lasers(e.g.,He:Ne lasers)with our SP-based laser for a projector,demonstrate effective suppression of speckle formation,reducing speckle contrast from 0.5 to 0.05.These findings offer a promising solution for improving the performance and quality of laser-based displays.展开更多
Perovskite materials have received extensive attention as optical gain media.However,it is tough to realize lasing using such materials on account of the unstable structure of MAPbl_(3)/CsPbl_(3)nanocrystals(NCs),and ...Perovskite materials have received extensive attention as optical gain media.However,it is tough to realize lasing using such materials on account of the unstable structure of MAPbl_(3)/CsPbl_(3)nanocrystals(NCs),and the propensity for mixed-halogen perovskites to undergo phase decomposition into bromine-rich and iodide-rich regions under intense laser irradiation.To solve this issue,we fabricated CsPbX_(3)(X=Br,I)NCs,which were embedded into a glassy matrix with high stability.In addition,by doping Brions into the CsPbl_(3) NCs to partially replace I^(-) ions,the optical efficiency and the optical gain properties were found to be significantly improved.Here,under 800 nm pulse laser excitation,red random lasing was realized with the assistance of such anion modulation.Moreover,we demonstrate that the perovskite NCs glasses(PNG)show strong water stability after immersion in water for one week,seeding a promise for application in high-definition(HD)displays and photonic devices.展开更多
Random lasing is observed in optically active resonators in the presence of disorder.As the optical cavities involved are open,the modes are coupled,and energy may pour from one state to another provided that they are...Random lasing is observed in optically active resonators in the presence of disorder.As the optical cavities involved are open,the modes are coupled,and energy may pour from one state to another provided that they are spatially overlapping.Although the electromagnetic modes are spatially localized,our system may be actively switched to a collective state,presenting a novel form of non-locality revealed by a high degree of spectral correlation between the light emissions collected at distant positions.In a nutshell,light may be stored in a disordered nonlinear structure in different fashions that strongly differ in their spatial properties.This effect is experimentally demonstrated and theoretically explained in titania clusters embedded in a dye,and it provides clear evidence of a transition to a multimodal collective emission involving the entire spatial extent of the disordered system.Our results can be used to develop a novel type of miniaturized,actively controlled all-optical chip.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.62174079)Guangdong Provincial Quantum Science Strategic Initiative(Grant No.GDZX2404006)Science,Technology and Innovation Commission of Shenzhen Municipality(Grant No.JCYJ20220530113015035)。
文摘CdSe nanoplatelets(NPLs)are promising candidates for on-chip light sources,yet their performance is hindered by surface defects and inefficient optical gain.Herein,we demonstrate that CdSeS crown passivation significantly enhances the photophysical property of CdSe NPLs.Laser spectroscopy techniques reveal suppressed electronic and hole trapping at lateral surfaces,leading to a 4.2-fold increase in photoluminescence quantum yield and a shortened emission lifetime from13.5 to 4.8 ns.In addition,amplified spontaneous emission is achieved under nanosecond pulse pumping,with thresholds of0.75 to 0.16 mJ/cm^(2)for CdSe and CdSe/CdSeS NPLs,respectively.By integrating CdSe/CdSeS NPLs with high-refractiveindex SiO2scatters,coherent random lasing is realized at a threshold of 0.21 mJ/cm^(2).These findings highlight the critical role of lateral surface passivation in optimizing optical gain and pave the way for low-cost,multifunctional nanophotonic devices.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11474021 and 51333001)the Key Program for International S&T Cooperation Projects of China(Grant No.2013DFB50340)+1 种基金the Issues of Priority Development Areas of the Research Fund for the Doctoral Program of Higher Education of China(Grant No.20120001130005)the Key(Key Grant)Project of Chinese Ministry of Education(Grant No.313002)
文摘In this paper,we investigate the bichromatic coherent random lasing actions from the dye-doped polymer stabilized blue phase liquid crystals.Two groups of lasing peaks,of which the full widith at half maximum is about 0.3 nm,are clearly observed.The shorter-and longer-wavelength modes are associated with the excitation of the single laser dye（DCM） monomers and dimers respectively.The experimental results show that the competition between the two groups of the lasing peaks can be controlled by varying the polarization of the pump light.When the polarization of the pump light is rotated from 0？to 90？,the intensity of the shorter-wavelength lasing peak group reduces while the intensity of the longer-wavelength lasing peak group increases.In addition,a red shift of the longer-wavelength modes is also observed and the physical mechanisms behind the red-shift phenomenon are discussed.
基金Project supported by the National Natural Science Foundation of China(Grant No.61378042)the Colleges and Universities in Liaoning Province Outstanding Young Scholars Growth Plans,China(Grant No.LJQ2015093)Shenyang Ligong University Laser and Optical Information of Liaoning Province Key Laboratory Open Funds,China
文摘A dye-doped polymer-dispersed liquid crystal film was designed and fabricated,and random lasing action was studied.A mixture of laser dye,nematic liquid crystal,chiral dopant,and PVA was used to prepare the dye-doped polymer-dispersed liquid crystal film by means of microcapsules.Scanning electron microscopy analysis showed that most liquid crystal droplets in the polymer matrix ranged from 30 μm to 40 μm,the size of the liquid crystal droplets was small.Under frequency doubled 532 nm Nd：YAG laser-pumped optical excitation,a plurality of discrete and sharp random laser radiation peaks could be measured in the range of 575–590 nm.The line-width of the lasing peak was 0.2 nm and the threshold of the random lasing was 9 m J.Under heating,the emission peaks of random lasing disappeared.By detecting the emission light spot energy distribution,the mechanism of radiation was found to be random lasing.The random lasing radiation mechanism was then analyzed and discussed.Experimental results indicated that the size of the liquid crystal droplets is the decisive factor that influences the lasing mechanism.The surface anchor role can be ignored when the size of the liquid crystal droplets in the polymer matrix is small,which is beneficial to form multiple scattering.The transmission path of photons is similar to that in a ring cavity,providing feedback to obtain random lasing output.
文摘A directional random laser mediated by transverse Anderson localization in a disordered glass optical fiber is reported.Previous demonstrations of random lasers have found limited applications because of their multi-directionality and chaotic fluctuations in the laser emission.The random laser presented in this paper operates in the Anderson localization regime.The disorder induced localized states form isolated local channels that make the output laser beam highly directional and stabilize its spectrum.The strong transverse disorder and longitudinal invariance result in isolated lasing modes with negligible interaction with their surroundings,traveling back and forth in a Fabry–Perot cavity formed by the air–fiber interfaces.It is shown that if a localized input pump is scanned across the disordered fiber input facet,the output laser signal follows the transverse position of the pump.Moreover,a uniformly distributed pump across the input facet of the disordered fiber generates a laser signal with very low spatial coherence that can be of practical importance in many optical platforms including image transport with fiber bundles.
基金the FNRS(Fonds National de la Recherche Scientifique,Belgium)for a FRIA doctoral fellowship and then a"Chargéde Recherches"fellowshipThis work was realised in the frame of the Belgian Federal Government PAI-IUAP program(INANOMAT P6/17)The financial support from the University of Namur(FUNDP),"Aide institutionnelle aux collaborations internationales"is also acknowledged.
文摘Optoelectronic nanocomposites are a new class of materials, which exhibit very interesting and particular properties and attract a growing attention due to their potential applications in information storage and optoelectronic devices. Zinc oxide, ZnO, is one of the most interesting binary semiconductor （3.37 eV） with very important optical properties, which can be used in the fields such as short wavelength lasers, blue light emitting diodes, UV detectors, gas sensors, etc. This paper reviews the very recent progress in the prepa- ration of silica-based ZnO nanocomposites. After an introduction reviewing the theoretical background, the article will begin with a survey of the optical properties and the quantum size effect （QSE） of ZnO/SiO2 nanocomposites prepared by the inclusion of ZnO nanoclusters inside silica mesoporous materials. The second part will focus on one of the most interesting properties of ZnO/SiO2 nanocomposites, which is the random lasing effect after one- and two-photon excitation. The final part will deal with the introduction of ZnO nanoparticles inside microporous zeolites and the observation of QSE. For comparison, the photoluminescence （PL） and QSE properties of ZnS nanoparticles occluded in mesoporous media are also described. New potential applications will be discussed since short-wavelength devices are required by industry to design, for instance, new information storage supports and biolabelling devices.
基金This work was financially supported by the National Natural Science Foundation of China(No.62205180)the Natural Science Foundation of Shandong Province(No.ZR2022QF029)the Taishan Scholar Program of Shandong Province(Young Scientist).
文摘Laser-based light sources are highly desirable for display applications due to their narrow emission linewidth and exceptional brightness.However,the coherence inherent in lasers often leads to the formation of unwanted speckles,which can significantly degrade display quality.Thus,there is a critical need for light sources that retain the narrow emission and high brightness of lasers while minimizing spatial coherence to reduce speckle formation.Random lasing has emerged as a promising strategy to address this issue,though its random emission directions can lead to energy losses.To overcome this challenge,we propose a novel approach in which CdSe nanoplatelets,known for their efficient optical gain properties,are self-assembled into supraparticles(SPs),serving as both scattering centers and gain media.This configuration enables random lasing,and by coupling the random gain medium to a Fabry-Perot(FP)cavity,we successfully direct the typically omnidirectional random lasing into a controlled,low-coherence emission.Our experimental results,comparing conventional lasers(e.g.,He:Ne lasers)with our SP-based laser for a projector,demonstrate effective suppression of speckle formation,reducing speckle contrast from 0.5 to 0.05.These findings offer a promising solution for improving the performance and quality of laser-based displays.
基金supported by the National Natural Science Foundation of China(Nos.52072271,51872207,and 61775187)Innovative project of Yunnan Key Laboratory of New Materials(No.2020KF005).
文摘Perovskite materials have received extensive attention as optical gain media.However,it is tough to realize lasing using such materials on account of the unstable structure of MAPbl_(3)/CsPbl_(3)nanocrystals(NCs),and the propensity for mixed-halogen perovskites to undergo phase decomposition into bromine-rich and iodide-rich regions under intense laser irradiation.To solve this issue,we fabricated CsPbX_(3)(X=Br,I)NCs,which were embedded into a glassy matrix with high stability.In addition,by doping Brions into the CsPbl_(3) NCs to partially replace I^(-) ions,the optical efficiency and the optical gain properties were found to be significantly improved.Here,under 800 nm pulse laser excitation,red random lasing was realized with the assistance of such anion modulation.Moreover,we demonstrate that the perovskite NCs glasses(PNG)show strong water stability after immersion in water for one week,seeding a promise for application in high-definition(HD)displays and photonic devices.
基金The research leading to these results has received funding from the ERC under the EC’s Seventh Framework Program(FP7/2007-2013)grant agreement n.201766,EU FP7 NoE Nanophotonics4Enery Grant No.248855the Spanish MICINN CSD2007-0046(Nanolight.es)+1 种基金MAT2009-07841(GLUSFA)and Comunidad de Madrid S2009/MAT2012-31659.
文摘Random lasing is observed in optically active resonators in the presence of disorder.As the optical cavities involved are open,the modes are coupled,and energy may pour from one state to another provided that they are spatially overlapping.Although the electromagnetic modes are spatially localized,our system may be actively switched to a collective state,presenting a novel form of non-locality revealed by a high degree of spectral correlation between the light emissions collected at distant positions.In a nutshell,light may be stored in a disordered nonlinear structure in different fashions that strongly differ in their spatial properties.This effect is experimentally demonstrated and theoretically explained in titania clusters embedded in a dye,and it provides clear evidence of a transition to a multimodal collective emission involving the entire spatial extent of the disordered system.Our results can be used to develop a novel type of miniaturized,actively controlled all-optical chip.
