Wuhan National Laboratory for Optoelectronics

Wuhan, China

Wuhan National Laboratory for Optoelectronics

Wuhan, China
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Wang B.,Wuhan National Laboratory for Optoelectronics
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

In order to improve the characteristic information of the fused images, we propose a novel infrared and visible image fusion algorithm based on image detail enhancement in this paper, the bilateral filter and dynamic range partitioning (BF & DRP) are used to improve the original infrared image, and the multi-scale retinex transform (MRT) also is used to deal with image fusion. Firstly a method of bilateral filter and dynamic range partitioning (BF & DRP) was used to improve the details of the low SNR and low contrast original infrared image, by which the edges of targets were strengthened, the noises were suppressed, and the constrast of infrared image was enhanced. Secondly, and finally, the multi-scale retinex transform was used to improve the fusion of visible and infrared image, by combining the multi-scale transform and regional fusion where the adaptive low frequency and high frequency coefficient were considered, which effectively suppressed the noises and enhanced the details. Experimental results proved the effectiveness of the proposed image fusion method. The salient color and texture feature of visible image was well preserved, the important details of infrared and visible image were highlighted. The results show that this algorithm is better than traditional image fusion method, such as wavelet transform, non-sampled contourlet transform, in in standard deviation, information entropy and Average gradient etc. the algorithm of this paper is able to preserve the details of image, increase the amount of importance characteristic information, is advantageous to the visual performance and distinguishability of fused image for human observation. © 2016 SPIE.


Zhou Y.,Wuhan National Laboratory for Optoelectronics | Li X.,McMaster University
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2017

We have proposed a novel scattered light computation microscopy (SLCM) that takes use of scattered light in imaging objects shaded by strongly scattering media. Based on the principle of light reciprocity, image is formed through computation in the SLCM method. Compared to the conventional scattered light fluorescence microscopy (SLFM) method, the SLCM doesn't need any pretreatment of objects. Simulation results have shown that subwavelength resolution can be achieved through the SLCM with optimized parameters. The good anti-noise capability of the SLCM is demonstrated by simulation as well. © 2017 SPIE.


Li C.,Wuhan National Laboratory for Optoelectronics
AIP Conference Proceedings | Year: 2017

In this paper, we proposed an optical splitter planar waveguide design with super multi channels. The design utilizes the wavefront interference and spatial filtering theory. The DC and AC spatial frequency components of the phase grating are separated spatially, and they are remerged at output plane after specific phase delay is added to the DC spatial frequency component. Therefore, the output field distribution is enhanced in some area and cancelled in the rest area in each period. Finally, the input beam is split into super multi channels. There is only phase modulation in the whole device without any amplitude modulation. Therefore, the insertion loss of the device is very small, theoretically. Besides, for the same branch number, the length of the device is smaller than that of conventional splitters based on Y branch and multimode interference. © 2017 Author(s).


News Article | April 28, 2016
Site: www.materialstoday.com

The secret to making the best energy storage materials is growing them with as much surface area as possible. This requires just the right mixture of ingredients prepared in a specific amount and order at just the right temperature to produce a thin sheet of material with the perfect chemical consistency to store energy. A team of researchers from Drexel University, and Huazhong University of Science and Technology (HUST) and Tsinghua University in China, recently discovered a way to improve the recipe and make the resulting materials both bigger and better at soaking up energy. The secret? Just add salt. The team's findings, which are published in a paper in Nature Communications, show that using salt crystals as a template to grow thin sheets of conductive metal oxides produces materials that are larger and possess a greater chemical purity, making them better suited for gathering ions and storing energy. "The challenge of producing a metal oxide that reaches theoretical performance values is that the methods for making it inherently limit its size and often foul its chemical purity, which makes it fall short of predicted energy storage performance," said Jun Zhou, a professor at HUST's Wuhan National Laboratory for Optoelectronics and an author of the paper. "Our research reveals a way to grow stable oxide sheets with less fouling that are on the order of several hundreds of times larger than the ones that are currently being fabricated." In an energy storage device – a battery or a capacitor, for example – energy is contained in the chemical transfer of ions from an electrolyte solution to thin layers of conductive materials. As these devices evolve, they're becoming smaller and capable of holding an electric charge for longer periods of time without needing a recharge. The reason for their improvement is that researchers are fabricating materials that are better equipped, structurally and chemically, for collecting and disbursing ions. In theory, the best materials for the job should be thin sheets of metal oxides, because their chemical structure and high surface area makes it easy for ions to bind to them – which is how energy storage occurs. But the metal oxide sheets that have been fabricated in labs thus far have fallen well short of their theoretical capabilities. According to the researchers, the problem lies in the process of making the metal oxide nanosheets, which involves either deposition from a gas or chemical etching. Both these processes often leave trace chemical residues that contaminate the material and prevent ions from bonding to it. In addition, materials made in this way are often just a few square micrometers in size. Using salt crystals as a substrate for growing the metal oxide crystals lets them spread out and form a larger sheet of oxide material. Analogous to making a waffle by dripping batter into a pan versus pouring it into a big waffle iron, the key to getting a big, sturdy product is getting the solution – be it batter or a chemical compound – to spread evenly over the template and stabilize in a uniform way. "This method of synthesis, called 'templating' – where we use a sacrificial material as a substrate for growing a crystal – is used to create a certain shape or structure," explained Yury Gogotsi, a professor in Drexel's College of Engineering and head of the A.J. Drexel Nanomaterials Institute, who was another author of the paper. "The trick in this work is that the crystal structure of salt must match the crystal structure of the oxide, otherwise it will form an amorphous film of oxide rather than a thin, strong and stable nanocrystal. This is the key finding of our research – it means that different salts must be used to produce different oxides." Researchers have used a variety of chemicals, compounds, polymers and objects as growth templates for nanomaterials, but this discovery shows the importance of matching a template to the structure of the material being grown. Salt crystals turn out to be the perfect substrate for growing oxide sheets of magnesium, molybdenum and tungsten. The precursor solution coats the sides of the salt crystals as the oxides begin to form. After they've solidified, the salt is dissolved in a wash, leaving nanometer-thin two-dimensional (2D) sheets on the sides of the salt crystals – and little trace of any contaminants that might hinder their energy storage performance. By making oxide nanosheets in this way, the only factors that limit their growth are the size of the salt crystals and the amount of precursor solution used. "Lateral growth of the 2D oxides was guided by salt crystal geometry and promoted by lattice matching and the thickness was restrained by the raw material supply. The dimensions of the salt crystals are tens of micrometers and guide the growth of the 2D oxide to a similar size," the researchers write in the paper. "On the basis of the naturally non-layered crystal structures of these oxides, the suitability of salt-assisted templating as a general method for synthesis of 2D oxides has been convincingly demonstrated." As predicted, the larger size of the oxide sheets equated to a greater ability to collect and disburse ions from an electrolyte solution – the ultimate test for energy storage devices. Results reported in the paper suggest that use of these materials may help in creating an aluminum-ion battery that could store more charge than the best lithium-ion batteries found in laptops and mobile devices today. Gogotsi, along with his students in Drexel’s Department of Materials Science and Engineering, has been collaborating with HUST since 2012 to explore a wide variety of materials for energy storage applications. The lead author of the Nature Communications paper, Xu Xiao, and co-author Tiangi Li, both Zhou's doctoral students, came to Drexel as exchange students to learn about its supercapacitor research. Those visits started a collaboration that was supported by Gogotsi's annual trips to HUST. While the partnership has already yielded five joint publications, Gogotsi speculates that this work is just beginning. "The most significant result of this work thus far is that we've demonstrated the ability to generate high-quality 2D oxides with various compositions," Gogotsi said. "I can certainly see expanding this approach to other oxides that may offer attractive properties for electrical energy storage, water desalination membranes, photocatalysis and other applications." This story is adapted from material from Drexel University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.


Home > Press > Adding some salt to the recipe for energy storage materials: Researchers use common table salt as growth template Abstract: The secret to making the best energy storage materials is growing them with as much surface area as possible. Like baking, it requires just the right mixture of ingredients prepared in a specific amount and order at just the right temperature to produce a thin sheet of material with the perfect chemical consistency to be useful for storing energy. A team of researchers from Drexel University, Huazhong University of Science and Technology (HUST) and Tsinghua University recently discovered a way to improve the recipe and make the resulting materials bigger and better and soaking up energy -- the secret? Just add salt. The team's findings, which were recently published in the journal Nature Communications, show that using salt crystals as a template to grow thin sheets of conductive metal oxides make the materials turn out larger and more chemically pure -- which makes them better suited for gathering ions and storing energy. "The challenge of producing a metal oxide that reaches theoretical performance values is that the methods for making it inherently limit its size and often foul its chemical purity, which makes it fall short of predicted energy storage performance," said Jun Zhou, a professor at HUST's Wuhan National Laboratory for Optoelectronics and an author of the research. Our research reveals a way to grow stable oxide sheets with less fouling that are on the order of several hundreds of times larger than the ones that are currently being fabricated." In an energy storage device -- a battery or a capacitor, for example -- energy is contained in the chemical transfer of ions from an electrolyte solution to thin layers of conductive materials. As these devices evolve they're becoming smaller and capable of holding an electric charge for longer periods of time without needing a recharge. The reason for their improvement is that researchers are fabricating materials that are better equipped, structurally and chemically, for collecting and disbursing ions. In theory, the best materials for the job should be thin sheets of metal oxides, because their chemical structure and high surface area makes it easy for ions to attach -- which is how energy storage occurs. But the metal oxide sheets that have been fabricated in labs thus far have fallen well short of their theoretical capabilities. According to Zhou, Tang and the team from HUST, the problem lies in the process of making the nanosheets -- which involves either a deposition from gas or a chemical etching -- often leaves trace chemical residues that contaminate the material and prevent ions from bonding to it. In addition, the materials made in this way are often just a few square micrometers in size. Using salt crystals as a substrate for growing the crystals lets them spread out and form a larger sheet of oxide material. Think of it like making a waffle by dripping batter into a pan versus pouring it into a big waffle iron; the key to getting a big, sturdy product is getting the solution -- be it batter, or chemical compound -- to spread evenly over the template and stabilize in a uniform way. "This method of synthesis, called 'templating' -- where we use a sacrificial material as a substrate for growing a crystal -- is used to create a certain shape or structure," said Yury Gogotsi, PhD, University and Trustee Chair professor in Drexel's College of Engineering and head of the A.J. Drexel Nanomaterials Institute, who was an author of the paper. "The trick in this work is that the crystal structure of salt must match the crystal structure of the oxide, otherwise it will form an amorphous film of oxide rather than a thing, strong and stable nanocrystal. This is the key finding of our research -- it means that different salts must be used to produce different oxides." Researchers have used a variety of chemicals, compounds, polymers and objects as growth templates for nanomaterials. But this discovery shows the importance of matching a template to the structure of the material being grown. Salt crystals turn out to be the perfect substrate for growing oxide sheets of magnesium, molybdenum and tungsten. The precursor solution coats the sides of the salt crystals as the oxides begin to form. After they've solidified, the salt is dissolved in a wash, leaving nanometer-thin two-dimensional sheets that formed on the sides of the salt crystal -- and little trace of any contaminants that might hinder their energy storage performance. By making oxide nanosheets in this way, the only factors that limit their growth is the size of the salt crystal and the amount of precursor solution used. "Lateral growth of the 2D oxides was guided by salt crystal geometry and promoted by lattice matching and the thickness was restrained by the raw material supply. The dimensions of the salt crystals are tens of micrometers and guide the growth of the 2D oxide to a similar size," the researchers write in the paper. "On the basis of the naturally non-layered crystal structures of these oxides, the suitability of salt-assisted templating as a general method for synthesis of 2D oxides has been convincingly demonstrated." As predicted, the larger size of the oxide sheets also equated to a greater ability to collect and disburse ions from an electrolyte solution -- the ultimate test for its potential to be used in energy storage devices. Results reported in the paper suggest that use of these materials may help in creating an aluminum-ion battery that could store more charge than the best lithium-ion batteries found in laptops and mobile devices today. Gogotsi, along with his students in the Department of Materials Science and Engineering, has been collaborating with Huazhong University of Science and Technology since 2012 to explore a wide variety of materials for energy storage application. The lead author of the Nature Communications article, Xu Xiao, and co-author Tiangi Li, both Zhou's doctoral students, came to Drexel as exchange students to learn about the University's supercapacitor research. Those visits started a collaboration, which was supported by Gogotsi's annual trips to HUST. While the partnership has already yielded five joint publications, Gogotsi speculates that this work is only beginning. "The most significant result of this work thus far is that we've demonstrated the ability to generate high-quality 2D oxides with various compositions," Gogotsi said. "I can certainly see expanding this approach to other oxides that may offer attractive properties for electrical energy storage, water desalination membranes, photocatalysis and other applications." For more information, please click If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.


The team's findings, which were recently published in the journal Nature Communications, show that using salt crystals as a template to grow thin sheets of conductive metal oxides make the materials turn out larger and more chemically pure—which makes them better suited for gathering ions and storing energy. "The challenge of producing a metal oxide that reaches theoretical performance values is that the methods for making it inherently limit its size and often foul its chemical purity, which makes it fall short of predicted energy storage performance," said Jun Zhou, a professor at HUST's Wuhan National Laboratory for Optoelectronics and an author of the research. Our research reveals a way to grow stable oxide sheets with less fouling that are on the order of several hundreds of times larger than the ones that are currently being fabricated." In an energy storage device—a battery or a capacitor, for example—energy is contained in the chemical transfer of ions from an electrolyte solution to thin layers of conductive materials. As these devices evolve they're becoming smaller and capable of holding an electric charge for longer periods of time without needing a recharge. The reason for their improvement is that researchers are fabricating materials that are better equipped, structurally and chemically, for collecting and disbursing ions. In theory, the best materials for the job should be thin sheets of metal oxides, because their chemical structure and high surface area makes it easy for ions to attach—which is how energy storage occurs. But the metal oxide sheets that have been fabricated in labs thus far have fallen well short of their theoretical capabilities. According to Zhou, Tang and the team from HUST, the problem lies in the process of making the nanosheets—which involves either a deposition from gas or a chemical etching—often leaves trace chemical residues that contaminate the material and prevent ions from bonding to it. In addition, the materials made in this way are often just a few square micrometers in size. Using salt crystals as a substrate for growing the crystals lets them spread out and form a larger sheet of oxide material. Think of it like making a waffle by dripping batter into a pan versus pouring it into a big waffle iron; the key to getting a big, sturdy product is getting the solution—be it batter, or chemical compound—to spread evenly over the template and stabilize in a uniform way. "This method of synthesis, called 'templating'—where we use a sacrificial material as a substrate for growing a crystal—is used to create a certain shape or structure," said Yury Gogotsi, PhD, University and Trustee Chair professor in Drexel's College of Engineering and head of the A.J. Drexel Nanomaterials Institute, who was an author of the paper. "The trick in this work is that the crystal structure of salt must match the crystal structure of the oxide, otherwise it will form an amorphous film of oxide rather than a thing, strong and stable nanocrystal. This is the key finding of our research—it means that different salts must be used to produce different oxides." Researchers have used a variety of chemicals, compounds, polymers and objects as growth templates for nanomaterials. But this discovery shows the importance of matching a template to the structure of the material being grown. Salt crystals turn out to be the perfect substrate for growing oxide sheets of magnesium, molybdenum and tungsten. The precursor solution coats the sides of the salt crystals as the oxides begin to form. After they've solidified, the salt is dissolved in a wash, leaving nanometer-thin two-dimensional sheets that formed on the sides of the salt crystal—and little trace of any contaminants that might hinder their energy storage performance. By making oxide nanosheets in this way, the only factors that limit their growth is the size of the salt crystal and the amount of precursor solution used. "Lateral growth of the 2D oxides was guided by salt crystal geometry and promoted by lattice matching and the thickness was restrained by the raw material supply. The dimensions of the salt crystals are tens of micrometers and guide the growth of the 2D oxide to a similar size," the researchers write in the paper. "On the basis of the naturally non-layered crystal structures of these oxides, the suitability of salt-assisted templating as a general method for synthesis of 2D oxides has been convincingly demonstrated." As predicted, the larger size of the oxide sheets also equated to a greater ability to collect and disburse ions from an electrolyte solution—the ultimate test for its potential to be used in energy storage devices. Results reported in the paper suggest that use of these materials may help in creating an aluminum-ion battery that could store more charge than the best lithium-ion batteries found in laptops and mobile devices today. Gogotsi, along with his students in the Department of Materials Science and Engineering, has been collaborating with Huazhong University of Science and Technology since 2012 to explore a wide variety of materials for energy storage application. The lead author of the Nature Communications article, Xu Xiao, and co-author Tiangi Li, both Zhou's doctoral students, came to Drexel as exchange students to learn about the University's supercapacitor research. Those visits started a collaboration, which was supported by Gogotsi's annual trips to HUST. While the partnership has already yielded five joint publications, Gogotsi speculates that this work is only beginning. "The most significant result of this work thus far is that we've demonstrated the ability to generate high-quality 2D oxides with various compositions," Gogotsi said. "I can certainly see expanding this approach to other oxides that may offer attractive properties for electrical energy storage, water desalination membranes, photocatalysis and other applications." Explore further: New nanosheet growth technique has potential to revolutionize nanotechnology industry


Zheng H.,Huazhong University of Science and Technology | Liu S.,Huazhong University of Science and Technology | Liu S.,Wuhan National Laboratory for Optoelectronics | Luo X.,Huazhong University of Science and Technology
Journal of Lightwave Technology | Year: 2013

High angular color uniformity (ACU) is strongly required in many illumination applications. In this study, we presented the phosphor dip-transfer coating method to realize high ACU for phosphor-converted white LEDs. The phosphor mixture was coated on top surfaces of LED chips and formed thin and convex phosphor layers by the dip-transfer coating. The optical simulations and experiments were conducted for performance verifications. Both numerical and experimental results show that the present method can obtain very high ACU. The angular correlated color temperature (CCT) deviation reaches 378 K when the average CCT of white LEDs is around 6200 K and it reduces to 63 K at the average CCT of about 4000 K. © 1983-2012 IEEE.


Tang Q.,Wuhan National Laboratory for Optoelectronics
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

The fundamental relations of the ultraviolet (UV) light transmittance of the soft polymer film filled by a large number of basic micro-pattern-structures composed of micro-squares, are acquired experimentally. The polymer films with different distribution density of basic color-micro-pattern-structure in the visible range, are also constructed easily, so as to perform single photomask photolithography for fabrication microlenses with very fine surface profile. The patterned polymer films demonstrate a modulated UV-light penetrating property. Models for describing the penetrating behaviors of UV-light over polymer films covered by a large number of basic grayscale or colorscale micro- patternstructures constructed, for instance, typical micro-square and other micro-pattern-structures shaped by partially overlapping several micro-squares, are set up. Several key factors, which influence the penetrating behavior of UV-light, and then the surface character, and also the quality of correspondent functioned micro-structures in photoresist and further substrate, such as diffractive or refractive microlens, are discussed carefully. The UV-light transmitting measurements demonstrate a desired UV-light intensity variance trend, which is basically consistent with theoretical prediction. © 2013 SPIE.


Qian Y.,Huazhong University of Science and Technology | Cao F.,Huazhong University of Science and Technology | Guo W.,Wuhan National Laboratory for Optoelectronics
Tetrahedron | Year: 2013

A novel series of solution-processable 3,6-disubstituted-fluorene-carbazole based host materials 36FCzG1 and 36FCzG2 are designed and synthesized. Owing to the highly asymmetry tetrahedral configuration, these hosts exhibit high glass transition temperatures (Tg) (161 and 162 C, respectively), high triplet energy levels (2.80 and 2.80 eV, respectively), excellent film forming capabilities, and chemical miscibility. Phosphorescent organic lighting-emitting diodes (OLEDs), which base on these host materials doped with the guests of iridium(III) bis(4,6-difluorophenylpyridinato)-picolinate (FIrpic) by spin coating, possesses a low turn-on voltage of 4.0 V, a maximum efficiency of 18.5 cd/A (8.1 lm/W), and a maximum external quantum efficiency of 10.3%. These results show that the devices are among the excellent solution processable blue phosphorescent OLEDs based on dendrimers. Furthermore, a novel way is developed to construct solution processable small molecules based on 3,6-disubstituted fluorene and carbazole dendrimers combined in a highly rigid configuration. © 2013 Elsevier Ltd. All rights reserved.


Yan J.,Wuhan National Laboratory for Optoelectronics | Gao M.,Wuhan National Laboratory for Optoelectronics | Zeng X.,Wuhan National Laboratory for Optoelectronics
Optics and Lasers in Engineering | Year: 2010

This paper investigated the microstructure and mechanical properties of 304 stainless steel joints by tungsten inert gas (TIG) welding, laser welding and laser-TIG hybrid welding. The X-ray diffraction was used to analyze the phase composition, while the microscopy was conducted to study the microstructure characters of joints. Finally, tensile tests were performed and the fracture surfaces were analyzed. The results showed that the joint by laser welding had highest tensile strength and smallest dendrite size in all joints, while the joint by TIG welding had lowest tensile strength, biggest dendrite size. Furthermore, transition zone and heat affected zone can be observed in the joint of TIG welding. The fractograph observation showed that the TIG welding joint existed as cup-cone shaped fracture, while the laser welding and hybrid welding joints existed as pure-shear fracture. The laser welding and hybrid welding are suitable for welding 304 stainless steel owing to their high welding speed and excellent mechanical properties. Crown Copyright © 2009.

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