All inorganic metal halide perovskite nanocrystals(NCs)have attracted much attention for their outstanding optoelectronic properties,which can be tuned by the composition,surface,size and morphology in nanoscale.Herei...All inorganic metal halide perovskite nanocrystals(NCs)have attracted much attention for their outstanding optoelectronic properties,which can be tuned by the composition,surface,size and morphology in nanoscale.Herein,we report the microfluidic synthesis of hollow CsPbBr_(3)perovskite NCs through the nanoscale Kirkendall effect.The formation mechanism of the hollow structure(Kirkendall void)controlled by the temperature,flow rate,ratios of precursors and ligands was investigated.Compared with the solid CsPbBr_(3)NCs of the same size,the hollow CsPbBr_(3)NCs exhibit blue shifts in ultraviolet-visible(UV-vis)absorption and photoluminescence(PL)spectra,and remarkably longer PL average lifetime(~98.2 ns).Quantum confinement effect,inner surface induced additional trap states and lattice strain of the hollow CsPbBr_(3)NCs were discussed in understanding their unique optoelectronic properties.The hollow CsPbBr_(3)NC based photodetector exhibits an outstanding negative photoconductivity(NPC)detectivity of 8.9×10^(12)Jones.They also show potentials in perovskite NC based photovoltaic and light emitting diodes(LEDs).展开更多
We present a highly efficient method of generating and shaping ellipse perfect vector beams (EPVBs) with a prescribed ellipse intensity profile and continuously variant linear polarization state. The scheme is based o...We present a highly efficient method of generating and shaping ellipse perfect vector beams (EPVBs) with a prescribed ellipse intensity profile and continuously variant linear polarization state. The scheme is based on the coaxial superposition of two orthogonally polarized ellipse laser beams of controllable phase vortex serving as the base vector components. The phase-only computer-generated hologram is specifically designed by means of a modified iteration algorithm involving a complex amplitude constraint, which is able to generate an EPVB with high diffraction efficiency in the vector optical field generator. We experimentally demonstrate that the efficiency of generating the EPVB has a notable improvement from 1.83% in the conventional complex amplitude modulation based technique to 11.1% in our method. We also discuss and demonstrate the simultaneous shaping of multiple EPVBs with independent tunable ellipticity and polarization vortex in both transversal (2D) and axial (3D) focusing structures, proving potentials in a variety of polarization-mediated applications such as trapping and transportation of particles in more complex geometric circumstances.展开更多
Digital holographic microscopy(DHM),which combines digital holography with optical microscopy,is a wide field,minimally invasive quantitative phase microscopy(QPM)approach for measuring the 3D shape or the inner struc...Digital holographic microscopy(DHM),which combines digital holography with optical microscopy,is a wide field,minimally invasive quantitative phase microscopy(QPM)approach for measuring the 3D shape or the inner structure of transparent and translucent samples.However,limited by diffraction,the spatial resolution of conventional DHM is relatively low and incompatible with a wide field of view(FOV)owing to the spatial bandwidth product(SBP)limit of the imaging systems.During the past decades,many efforts have been made to enhance the spatial resolution of DHM while preserving a large FOV by trading with unused degrees of freedom.Illumination modulation techniques,such as oblique illumination,structured illumination,and speckle illumination,can enhance the resolution by adding more high-frequency information to the recording system.Resolution enhancement is also achieved by extrapolation of a hologram or by synthesizing a larger hologram by scanning the sample,the camera,or inserting a diffraction grating between the sample and the camera.For on-chip DHM,spatial resolution is achieved using pixel super-resolution techniques.In this paper,we review various resolution enhancement approaches in DHM and discuss the advantages and disadvantages of these approaches.It is our hope that this review will contribute to advancements in DHM and its practical applications in many fields.展开更多
基金supported by the National Natural Science Foundation of China(Nos.22175095 and 62175112)the National Key R&D Program of China(No.2022YFA1204404).
文摘All inorganic metal halide perovskite nanocrystals(NCs)have attracted much attention for their outstanding optoelectronic properties,which can be tuned by the composition,surface,size and morphology in nanoscale.Herein,we report the microfluidic synthesis of hollow CsPbBr_(3)perovskite NCs through the nanoscale Kirkendall effect.The formation mechanism of the hollow structure(Kirkendall void)controlled by the temperature,flow rate,ratios of precursors and ligands was investigated.Compared with the solid CsPbBr_(3)NCs of the same size,the hollow CsPbBr_(3)NCs exhibit blue shifts in ultraviolet-visible(UV-vis)absorption and photoluminescence(PL)spectra,and remarkably longer PL average lifetime(~98.2 ns).Quantum confinement effect,inner surface induced additional trap states and lattice strain of the hollow CsPbBr_(3)NCs were discussed in understanding their unique optoelectronic properties.The hollow CsPbBr_(3)NC based photodetector exhibits an outstanding negative photoconductivity(NPC)detectivity of 8.9×10^(12)Jones.They also show potentials in perovskite NC based photovoltaic and light emitting diodes(LEDs).
基金National Key R&D Program of China (2018YFA0306200)National Natural Science Foundation of China (NSFC) (91750202,11474156,61605080,61775097)China Postdoctoral Science Foundation (2016M601775)
文摘We present a highly efficient method of generating and shaping ellipse perfect vector beams (EPVBs) with a prescribed ellipse intensity profile and continuously variant linear polarization state. The scheme is based on the coaxial superposition of two orthogonally polarized ellipse laser beams of controllable phase vortex serving as the base vector components. The phase-only computer-generated hologram is specifically designed by means of a modified iteration algorithm involving a complex amplitude constraint, which is able to generate an EPVB with high diffraction efficiency in the vector optical field generator. We experimentally demonstrate that the efficiency of generating the EPVB has a notable improvement from 1.83% in the conventional complex amplitude modulation based technique to 11.1% in our method. We also discuss and demonstrate the simultaneous shaping of multiple EPVBs with independent tunable ellipticity and polarization vortex in both transversal (2D) and axial (3D) focusing structures, proving potentials in a variety of polarization-mediated applications such as trapping and transportation of particles in more complex geometric circumstances.
基金the National Key Research and Development Program of China(2021YFF0700300)the National Natural Science Foundation of China(NSFC 62075177,62175112)+1 种基金the Natural Science Foundation of Shaanxi Province(2020JM-193 and 2020JQ-324)the Fundamental Research Funds for the Central Universities(XJS210503,XJS210504,JC2112,and JB210513).
文摘Digital holographic microscopy(DHM),which combines digital holography with optical microscopy,is a wide field,minimally invasive quantitative phase microscopy(QPM)approach for measuring the 3D shape or the inner structure of transparent and translucent samples.However,limited by diffraction,the spatial resolution of conventional DHM is relatively low and incompatible with a wide field of view(FOV)owing to the spatial bandwidth product(SBP)limit of the imaging systems.During the past decades,many efforts have been made to enhance the spatial resolution of DHM while preserving a large FOV by trading with unused degrees of freedom.Illumination modulation techniques,such as oblique illumination,structured illumination,and speckle illumination,can enhance the resolution by adding more high-frequency information to the recording system.Resolution enhancement is also achieved by extrapolation of a hologram or by synthesizing a larger hologram by scanning the sample,the camera,or inserting a diffraction grating between the sample and the camera.For on-chip DHM,spatial resolution is achieved using pixel super-resolution techniques.In this paper,we review various resolution enhancement approaches in DHM and discuss the advantages and disadvantages of these approaches.It is our hope that this review will contribute to advancements in DHM and its practical applications in many fields.
