Napra Co ., Ltd. (Tokyo, JP) inventor Shigenobu Sekine has created the means to quickly manufacture nano-structured powders with an extremely small, highly uniform spherical shape and high sphericity. The process can be used to create nano-metals and nano-alloys composed of any single metals or alloys using a self-assembling procedure.
The metal powders are produced by an apparatus in which molten metal, alloys or composites are dropped onto a fast-rotating dish shaped disk in an atmosphere containing one or more inert gases and a small amount of oxidizing gas, and the molten metal is dispersed to be tiny droplets for a predetermined time using centrifugal force, within a cooling-reaction gas, and cooled rapidly to form spherical particles. The products are characterized as nanoparticles being 1) substantially crystalline; 2) substantially amorphous; or 3) of controlled porosity.
The nano-structured powder particles may be used as the starting materials of magnets, catalysts, electrodes, batteries, heat insulators, refractory materials, and sintered metals. For instance, the powders of the rare earth-iron-boron (R--Fe--B) alloy with the nanocomposite structure may be used a starting material for producing a sintered magnet or bonded magnet having excellent magnetic characteristics. The resulting novel nanostructure consists of micro-sized ferromagnetic phase and novel nano-sized nonmagnetic phase providing for the overall novel nanocomposite.
The apparatuses, systems and self assembling processes of Sekine’s invention provides for the production of very small, spherical particles having a nano-composite structure which is a particularly important feature for producing high utility, strong, permanent magnetic powders. Conventional apparatuses and methods "cannot produce a nanocomposite magnetic material at all, and certainly not in the form tiny spherical powders by a self-assembly technique," according to Sekine, in U.S. Patent Application 20090304834.
U.S. Patent Application 20090304834, FIG. 1 shows a preferred embodiment of the system for making metal powders with a nano-composite structure from molten metals, including the centrifugal granulation apparatus (also described in U.S. Patent 7,547,346, June 16, 2009)
The spinning disk rotates at high speed ranging from 50,000 to 100,000 rpm. Such speeds may be attained by using an electric motor employing an electromagnetic "bearings" spindle, as commercially available. The diameter of the spinning disk and the rotational speed of the disk both contribute to the centrifugal effect on the dispersed droplets. A measure of this effect is the product of the disk diameter and the rotational speed of the disk. Thus, a 30 mm diameter disk rotating at 50,000 rpm results in 1,500,000 rpm-mm. A 30 mm diameter disk rotating at 100,000 rpm results in 3,000,000 rpm-mm. A 40 mm diameter disk rotating at 50,000 rpm results in 2,000,000 rpm-mm.
Various kinds of the powders of metals, metal oxides, metal nitrides, metal silicides, and their mixed compounds have been used as the crude starting materials to produce such materials as magnets, catalysts, electrodes, batteries, heat insulators, refractory substances, and sintered metals.
However such powders commonly suffer from poor uniformity of composition, shape, granularity and for spherical powders, poor sphericity (degree of roundness). A mechanical pulverization apparatus is capable of producing particles that have fine structure and are composed of more than two types of components. While of possibly uniform composition, such particles are of poor uniformity in size and shape, and of course are not of spherical shape. Moreover, it is difficult to obtain a nanocomposite structure using mechanical pulverization for the production of fine powders.
In contrast to pulverization manufacturing methods, Sekine's fast spinning molten metal system is able to produce extremely small powders with a highly uniform spherical shape, having high sphericity, and composed of metal including single metals and alloys, including nano-composite structures, using a self-assembling procedure.
U.S. Patent Application 20090304834, FIGS. 2A and 2B show scanning electron microscope (SEM) images of the powder particles (cross section size of about 20 .mu.m diameter) respectively produced according to Napra's system for producing crystalline (nanocomposite) spherical particles (2A) and conventionally produced metal spherical particles (2B).
The nanocomposite structures provide for a permanent magnet with excellent magnetic properties employing nano-sized, non-magnetic material, which is a rare earth oxide, ROx, R2O3, RO, RO2, such as neodymium oxide or praseodymium oxide, (or MOx where M is a minor metal) that is incorporated at the inside of ferromagnetic grains, such as R--Fe--B, and/or at their grain boundaries.
Usually, Nd is preferably employed as R, and rare earth elements such as Pr is favorably employed. Nd2O3, RO and RO2 are preferably used in the Napra system. The resulting novel nanostructure consists of micro-sized ferromagnetic phase and novel nano-sized nonmagnetic phase providing for the overall novel nanocomposite structure. The aggregate of nano-sized metal components are separated within the particles by layers or discrete nano-sized bodies of metal oxides, metal nitrides, metal silicides, or separated by evacuated spaces, e.g. pores.
Napra's machine is able produce powder of extremely small, highly uniform spherical shape and high sphericity, composed of substantially amorphous or crystalline (e.g., nanocomposites) composition with controlled porosity.
Amorphous spherical nanoparticles may be composed of almost any metal or metal alloy. Such metals include: Fe, Ni, Sn, Ti, Cu and Ag with combinations of Ni--Al, Sn--Ag--Cu, B--Fe--Nd (and its variations) and Al--Ni--Co--Fe. More generally, the metals also include the following and includes combinations of them: Ag, Cu, Ni, Al, Ti, V, Nb, Cr, Mo, Mn, Fe, B, Ru, Co, Pd, Pt, Au, Zn, Cd, Ga, In, Ti, Ge, Sn, Pb, Sb, Bi, Ce, Pr and Nd.
The high degree of sphericity and high uniformity of spherical shape (high proportion having the same spherical shape) are further shown in the scanning electron microscope (SEM) images of FIG. 6 (176.times. magnification) and FIG. 7 (704.times. magnification).
FIGS. 2A and 2B (Napra’s U.S. Patent 7,547,346) show another scanning electron microscope (SEM) images of the powder particles (cross section size of about 20 .mu.m diameter) respectively produced (crystalline (nanocomposite) spherical particles) and (conventional metal spherical particles).
Facultes Universitaires Notre-Dame De La Paix (Namur, BE) researchers detail a number of hydroxide and carbonate-based catalyst supports used for manufacturingmultiwall carbon nanotubes (MWNT) and single wall carbon nanotubes (SWNT) in U.S. Patent Application 20090325788. The inventors claim the new catalyst supports do not produce large amounts of soot and amorphous carbon along with the carbon nanotubes as do many common catalyst supports now used.
Inventors Janos B. Nagy, Narasimaiah Nagaraju, Isabelle Willems and Antonio Fonseca prepared carbon nanotubes by the catalytic decomposition of hydrocarbons using a technique called CCVD (Catalytic Carbon Vapor Deposition), carried out in the presence of catalysts to produce both MWNTs and SWNTs. Soot and encapsulated metal nanoparticles are the other by-products. The hydrocarbon can be acetylene, ethylene, butane, propane, ethane, methane or any other gaseous or volatile carbon containing compound. The catalyst, a transition metal, is generally, either pure or dispersed on a support.
The presence of a support for the catalyst affects the activity of the catalysts tremendously in the formation of carbon nanotubes. The selectivity of the catalyst for the production of nanotubes also depends on the type of catalyst support interaction.
The most common supports used to prepare supported catalyst for carbon nanotubes production are oxides i.e., silica, alumina, silica-alumina mixtures, magnesium oxide, calcium oxide, titanium oxide, cerium oxide, zeolites, spinels and graphite. The use of porous materials (i.e., silica, alumina, zeolites, etc.) as supports for catalysts, contaminates the carbon nanotubes produced thereon with a large amount of soot and amorphous carbon, while dissolving the support during the purification of the carbon nanotubes.
The Notre-Dame De La Paix hydroxide and carbonate-based catalyst supports do not present the contamination drawbacks of the catalyst supports of the state of the art.
The carbon nanotubes production on the supported catalyst by CCVD comprises the following steps:
Spreading manually or mechanically an appropriate amount of supported catalyst on a quartz boat to be used as bed for the supported catalyst in the fixed bed reactor. In the case of a moving bed reactor, the supported catalyst is spread continuously or by intermittence mechanically or manually on the moving bed of the reactor.
The reactor, containing the supported catalyst, is either kept initially at the appropriate constant reaction temperature (400-1200.degree. C.), or it is heated to the reaction temperature for an appropriate time of the reaction. Inert or reactant gas(es) can be passed over the supported catalyst during that step.
The pure or diluted hydrocarbon is passed over the supported catalyst at a predetermined temperature. Carbon nanotubes are grown on the supported catalyst as a result of the CCVD reaction. Diluted hydrocarbons are obtained by mixing at least one hydrocarbon with other gases such as nitrogen, argon, helium, hydrogen, CO, etc.
The crude nanotubes, composed of a mixture of carbon nanotubes and spent supported catalyst, is collected either continuously in the case of a moving bed reactor or stepwise in the case of a fixed bed reactor. Preferably, the carbon nanotubes purification is carried out by dissolving the spent supported catalyst as follows:
Stirring the crude nanotubes in a concentrated basic solution, preferably a concentrated NaOH solution, at a temperature in between 100-250.degree. C. Recovering the solid product by filtration and preferably washing it until a neutral pH is obtained. This first step is not necessary if the catalyst support contains only Mg and/or Ca derivatives.
Stirring the product in a concentrated acidic solution, preferably a concentrated HCl solution, at a temperature in between 0-120.degree. C.
Recovering the solid product (purified carbon nanotubes) by filtration and preferably washing until a neutral pH is obtained.
Finally purified carbon nanotubes are dried by air flow on a filter or by a rotary evaporator or by the use of a vacuum pump or by the use of an oven or a furnace. Preferably, the oven or furnace is heated at temperatures varying from 30.degree. C. to 400.degree. C. in air or from 30.degree. C. to 1200.degree. C. under vacuum or inert atmosphere.
FIG. 3a represents a low magnification Transmission Electron Microscopy (TEM) image of as made MWNTs, synthesized by acetylene decomposition at 700.degree. C. in a continuous reaction of 60 min, on the supported catalyst SCA2. The catalyst was activated by preheating 10 min in N2 flow.
FIG. 3b represents a higher magnification TEM image of MWNTs synthesized as in FIG. 3a.
FIG. 3c represents a low magnification TEM image of as made carbon fibers, synthesized by acetylene decomposition at 700.degree. C. in a continuous reaction of 60 min, on the supported catalyst SCA63. The catalyst was activated by preheating 10 min in N2 flow.
FIG. 3d represents a low magnification TEM image of purified SWNTs, in bundles, synthesized by CH4/H2 decomposition at 1000.degree. C. for 6 min, on the supported catalyst SCC81. The catalyst was activated by 4 min of in situ preheating from 25 to 1000.degree. C. in a CH4/H2 flow.
FIG. 4a represents the inner and outer diameter distribution histograms of the MWNTs synthesized as in FIG. 3a. The average inner and outer diameter of the MWNTs was found to be 4.7 and 9.7 nm, respectively. No amorphous carbon is noticed either in the sample or on the walls of the tubes. The tubes are generally turbostratic with some defects in the outer surface.
FIG. 4b represents the number of walls as a function of the inner diameter distribution of the MWNTs synthesized as in FIG. 3a. These MWNTs are obtained by acetylene decomposition at 700.degree. C. in a continuous reaction for 60 min on the supported catalyst SCA2. The supported catalyst was activated by preheating it for 10 min in a flow of N2. The number of walls of the MWNTs is in the range of 2-26 and the average value is 8.
Scientists at Arizona State University have developed an elegant method for significantly improving the memory capacity of electronic chips.
Led by Michael Kozicki, an ASU electrical engineering professor and director of the Center for Applied Nanoionics, the researchers have shown that they can build stackable memory based on “ionic memory technology,” which could make them ideal candidates for storage cells in high-density memory. Best of all, the new method uses well-known electronics materials.
“This opens the door to inexpensive, high-density data storage by ‘stacking’ memory layers on top one another inside a single chip,” Kozicki said. “This could lead to hard drive data storage capacity on a chip, which enables portable systems that are smaller, more rugged and able to go longer between battery charges.”
“This is a significant improvement on the technology we developed two years ago where we made a new type of memory that could replace Flash, using materials common to the semiconductor industry (copper-doped silicon dioxide). What we have done now is add some critical functionality to the memory cell merely by involving another common materia – silicon.”
Kozicki outlined the new memory device in a technical presentation he made in November at the 2009 International Electron Devices and Materials Symposia in Taiwan. He worked with Sarath C. Puthen Thermadam, an ASU electrical engineering graduate student.
Kozicki said that given current technology, electronics researchers are fast reaching the physical limits of device memory. This fact has spurred research into new types of memory that can store more information into less and less physical space. One way of doing this is to stack memory cells.
The concept of stackable memory is akin to one’s ability to store boxes in a small room. You can store more boxes (each representing a memory cell) if you stack them and take advantage of three dimensions of the room, rather than only putting each box on the floor.
Kozicki said stacking memory cells has not been achieved before because the cells could not be isolated. Each memory cell has a storage element and an access device; the latter allowing you to read, write or erase each storage cell individually.
“Before, if you joined several memory cells together you wouldn’t be able to access one without accessing all of the others because they were all wired together,” Kozicki said. “What we did was put in an access, or isolation device, that electrically splits all of them into individual cells.”
Up until now, people built these access elements into the silicon substrate.
“But if you do that for one layer of memory and then you build another layer, where will you put the access device,” Kozicki asked. “You already used up the silicon on the first layer and it’s a single crystal, it is very difficult to have multiple layers of single crystal material.”
The new approach does use silicon, but not single crystal silicon, which can be deposited in layers as part of the three-dimensional memory fabrication process. Kozicki said his team was wrestling with how to find a way to build an electrical element, called a diode, into the memory cell. The diode would isolate the cells.
Kozicki said this idea usually involves several additional layers and processing steps when making the circuit, but his team found an elegant way of achieving diode capability by substituting one known material for another, in this case replacing a layer of metal with doped silicon.
“We can actually use a number of different types of silicon that can be layered,” he said. “We get away from using the substrate altogether for controlling the memory cells and put these access devices in the layers of memory above the silicon substrate.”
“Rather than having one transistor in the substrate controlling each memory cell, we have a memory cell with a built-in diode (access device) and since it is built into the cell, it will allow us to put in as many layers as we can squeeze in there,” Kozicki said. “We’ve shown that by replacing the bottom electrode with silicon it is feasible to go any number of layers above it.
With each layer applied, memory capacity significantly expands.
“Stackable memory is thought to be the only way of reaching the densities necessary for the type of solid state memory that can compete with hard drives on cost as well as information storage capacity,” Kozicki said. “If you had eight layers of memory in a single chip, this would give you almost eight times the density without increasing the area.”
Kozicki said the advance mimics an idea employed in early radios.
“We created a modern analog to the ‘cat’s whisker,’ where we are growing a nanowire, a copper nanowire, right onto the silicon to create a diode,” he said.
Cat’s whisker radios, a product of the 1930s, were simple devices that employed a small wire to scratch the surface of a semiconductor material. The connection between the semiconductor and the wire created a diode that they could use as part of a radio.
“It turns out to be a ridiculously simple idea, but it works,” Kozicki said of his stackable memory advance. “It works better than the complicated ideas work.”
“The key was the diodes, and making a diode that was simple and essentially integrated in with the memory cell. Once you do that, the rest is pretty straightforward.”
Elpida Memory, Inc. (Tokyo. JP), Japan's leading global supplier of Dynamic Random Access Memory (DRAM), on December 22nd announced that its Hiroshima Plant has begun volume production of 40nm process 2-gigabit DDR3 SDRAMs. Since completing development of the DDR3 SDRAM last October it has taken Elpida only two months to ramp up mass production.
The new 2-gigabit DDR3 SDRAM achieves 44% more chips per wafer compared with Elpida's 50nm DDR3 SDRAM and a 100% yield for DDR3 products that operate at 1.6Gbps, the fastest speed standard for current DDR3. It also supports high-speed products. Compared with 50nm products, it uses about two-thirds less current and supports 1.2V/1.35V operation as well as DDR3 standard 1.5V, resulting in reduced power consumption of around 50%.
Initially, Elpida plans a phased expansion of 40nm 2-gigabit DDR3 SDRAM mass production at its Hiroshima Plant. In the second quarter of 2010, 40nm process production will also begin at Rexchip, a subsidiary in Taiwan, to increase the manufacture of 40nm process products in order to lower products costs. Depending on conditions in the DRAM market, Elpida may transfer 40nm process technology to foundry partners ProMOS and Winbond to expand production based on this technology to an even higher level.
Elpida Memory, Inc. (Tokyo: 6665) is a leading manufacturer of Dynamic Random Access Memory (DRAM) integrated circuits. The company's design, manufacturing and sales operations are backed by world class technological expertise. Its 300mm manufacturing facilities, consisting of its Hiroshima Plant and a Taiwan-based joint venture, Rexchip Electronics, utilize the most advanced manufacturing technologies available. Elpida's portfolio features such characteristics as high-density, high-speed, low power and small packaging profiles. The company provides DRAM solutions across a wide range of applications, including high-end servers, mobile phones and digital consumer electronics. More information can be found at http://www.elpida.com.
University of Louisiana at Lafayette (Lafayette, LA) Professor of Metallurgy Dr. Devesh K. Misra discloses how to make dendritic magnetic nanostructures for use in medical, sensor, drug delivery and magnetic recording applications in U.S. Patent 7,635,518. Dendrites are typically the tree-like structures, examples of which include crystals that grow as molten metal freezes; the tree-like structures that form during the freezing of many nonmetallic substances such as ice; and the like. Dendrites are sometimes referred to as having a "spiky" morphology.
Each nanorod of the dendritic magnetic nanostructure is comprised of a chain of nanoparticles that are held together by dipole interaction during their formation by precipitation within the aqueous core of a reverse micelle when an effective magnetic field is applied. Each nanoparticle is comprised of at least two elements, one of which is a magnetic metal.
Misra prepares dendritic magnetic nanostructures at room temperature by applying a magnetic field to a reverse micelle system wherein at least one salt of a magnetic metal is being precipitated within the core of the reverse micelle.
Quasi one-dimensional magnetic nanostructures, such as nanorods, nanowires, and nanotubes have attracted significant scientific and technological interest because they exhibit unique magnetic properties not displayed by their bulk or nanoparticle counterparts. Crystalline magnetic nanorods belong to this class of magnetic materials known for their spontaneous magnetization. There are multiple potential uses for such nanostructures, such as: their use for high density magnetic recording media; their use in sensors; their use in spintronic devices, and their use in drug delivery applications.
Misra also created titania coated magnetic nanostructures that are suitable for use in biomedical applications because the photocatalytic properties of the titania can be exploited for antimicrobial, or germicidal, activity. The magnetic properties of the nanorods are used to remove the titania coated nanostructures, when applied to the human body, such as when applied to a wound.
A variety of methods have been proposed for synthesizing various types of nanorods. These synthetic methods are typically anisotropic growth with the intrinsic anisotropic crystal structure in a solid material, anisotropic growth using tubular templates, and anisotropic growth kinetically controlled by super-saturation or by using an appropriate capping surfactant. Other approaches to fabricate one-dimensional nanostructures include thermal evaporation and template assisted growth, vapor phase transport process with the assistance of metal catalysts, hydrothermal methods, and electrospinning.
Misra’s method for producing magnetic nanostructures is comprised of an assembly of magnetic nanorods held together by dipole interaction in a dendritic pattern, includes the following steps:
a) dissolving an effective amount of a surfactant into a non-polar organic solvent with sufficient mixing to cause the formation of a reverse micelle microemulsion;
b) dividing said reverse micelle microemulsion into a first fraction and a second fraction;
c) blending into said first fraction an aqueous solution having dissolved therein one or more metal salts wherein at least one of the metals has magnetic properties, thereby forming a metal salt microemulsion comprised of reverse micelles in a continuous non-polar organic phase, which reverse micelles are comprised of an aqueous core of metal salt solution encased in a surfactant shell;
d) blending into said second fraction an effective amount of an aqueous precipitating agent solution, thereby resulting in the formation of a precipitating agent microemulsion comprised of reverse micelles in a continuous non-polar organic phase, which reverse micelles are comprised of an aqueous core of precipitating agent solution encased in a surfactant shell;
e) simultaneously: (i) applying a magnetic field of effective strength; and (ii) blending at least a portion of the metal salt microemulsion with at least a portion of the precipitating agent microemulsion, thereby resulting in the simultaneous precipitation and formation of magnetic nanostructures comprised of an assembly of magnetic nanorods held together by dipole interaction in a dendritic pattern, which nanorods are comprised of a series of magnetic nanoparticles held together by dipole magnetic forces, in the aqueous core of said reverse micelles;
f) extracting at least a portion of the magnetic nanostructures with an effective amount of a C2 to about a C6 alcohol wherein the magnetic nanostructures migrate to the alcohol phase in the form of a colloidal dispersion alcohol phase;
g) separating the colloidal dispersion alcohol phase from the non-polar organic phase; and h) heating said colloidal dispersion alcohol phase of step g) above at an effective temperature for an effective amount of time to drive off at least a portion of any remaining water and surfactant, thereby resulting in substantially dried magnetic nanostructures comprised of assemblies of magnetic nanorods held together in a dendritic pattern by dipole interaction.
Nanoparticles that can comprise the nanorods include M-Au, M-Ag, M-Pt, M-Pd, M-Au--Pt, M-Sm, and Nd-M-B wherein M is a magnetic metal selected from iron, nickel and cobalt.
DARPA is offering $25 million in grants for its new Information in a Photon (InPho) program to maximize the use of photons. The Information in a Photon Broad Agency Announcement seeks proposals addressing the basic science and the associated unifying physical and mathematical principles that govern the information capacity of optical photons, exploiting all relevant physical degrees of freedom.
The photon, the indivisible unit of electromagnetic energy, is a fundamental carrier of information. Numerous degrees of freedom are available for the conveyance of information on a photon including frequency, phase, arrival time, polarization, orbital angular momentum, linear momentum, superposition states, correlation, entanglement, etc.
DARPA Information in a Photon Goals
Because optical photons (l = 0.5mm) are approximately 106 times more costly (i.e., energetic) than their RF (f = 1GHz) counterparts, optical photons represent a critical resource within a wide variety of military applications ranging from fiber and free-space optical communications systems to various visible (VIS) and infrared (IR) sensing platforms. Motivated by both the high cost and application-centrality of optical photons we seek to extract maximum benefit from this valuable resource.
The primary goal of the Information in a Photon (InPho) program is to pursue the basic science and the associated unifying physical and mathematical principles that govern the information capacity of optical photons, exploiting all relevant physical degrees of freedom. Important outcomes of the InPho program will include (a) the rigorous quantification of photon information content for communications and imaging applications in both the classical and quantum domains, (b) novel methodologies to maximize the scene information that can be extracted from received photons in next-generation imaging/sensing platforms, and (c) novel methodologies to maximize the information content of transmitted/received photons in next-generation communication systems. Additional applications expected to benefit from a deeper understanding of photon information content include, but are not limited to, chemical/biological sensors, laser designators, navigation systems, photogrammetric applications and/or various forms of spectroscopy.
Program Description
The goal of the Information in a Photon (InPho) program is to pursue the fundamental physics governing the information content of optical photons. The success of this program will result in our ability to quantify the fundamental information content of a photon and exploit this information capacity for imaging/sensing and communications applications of importance to DoD.
The InPho program will consist of three thrust areas: Scientific Foundations, Imaging, and Communications. The objective of the Scientific Foundations Thrust will be to rigorously quantify photon information content for communications and imaging applications in both the classical and quantum domains. The result of this thrust will be to establish the basic scientific principles and associated mathematical formalisms that will facilitate efficient pursuit of the remaining two thrust areas.
Basic research in the Imaging Thrust will be directed toward extracting maximum scene information from minimum photon count. Conventional wisdom suggests that an image requires more than 1000 photons per pixel in order to be useful. This traditional rule-of-thumb, when combined with a desire for ever-increasing pixel-counts, can result in large apertures and/or long integration times which in turn increase both complexity (e.g., the need for stabilization) and/or size, weight and power (SWaP) costs (e.g., large glass mass).
It is apparent that current imaging systems under-utilize photon information capacity. Consider a natural scene that is imaged using an 8 bit per pixel focal plane. With a requirement to collect 1000 photons per pixel we see that such a system achieves a photon efficiency of 125 photons per bit or 8e-3 bits per photon (bpp). Because of the redundancy that is characteristic of natural imagery, it is not uncommon for such a scene to be visually indistinguishable after compression by 10x, suggesting an even lower photon information efficiency of 8e-4 bpp. Drastically increasing this photon efficiency will provide revolutionary capabilities for DoD VIS/IR imaging platforms.
Basic research in the Communications Thrust will be directed toward maximizing the information content of every transmitted/received photon in a free-space optical (FSO) communication system. Recent progress on the information capacity of optical communications has largely focused on novel spectrally dense modulation techniques for increasing the spectral information efficiency of these channels. Recent demonstrations approaching 10 bits/sec/Hz in fiber suggest that similar techniques may also be successfully employed for FSO applications. Unfortunately, these spectrally efficient solutions are generally photon inefficient, often achieving < 1e-3 bpp.
Conversely, photon-efficient modulation such as pulse position modulation (PPM) has been used to demonstrate 2 bpp with only a modest spectral efficiency of 0.25 bits/sec/Hz. The Shannon limit for FSO channels that employ multiple photon degrees of freedom can be several orders of magnitude higher than any of these recent hero experiments. Approaching the Shannon limit therefore will drastically increase photon efficiency and will provide revolutionary capabilities for optical communications systems within a wide array of DoD applications. It is expected that such efficiency gains will also positively impact fiber-based communications systems.
DARPA is soliciting innovative research proposals focusing on maximizing the information content of optical photons within the context of imaging and communication applications. All proposed research must fully address the Scientific Foundation thrust and its corresponding end-of-program goal. In addition to describing research within the Scientific Foundation Thrust, all proposals must also choose one of the four technical areas of interest outlined below (i.e. classical imaging, quantum imaging, classical communications, or quantum communications) and only address the corresponding end-of program goals listed in Table 1. Although proposals received under this BAA will focus on a single Technical Area, we anticipate that individual researchers may participate in multiple teams when their expertise is clearly relevant to more than one.
Proposed research should investigate innovative approaches that enable revolutionary advances in science, devices, or systems aimed at maximizing the information capacity of optical photons. Specifically excluded is research that primarily results in evolutionary improvements to the existing state of practice.
Collaborative efforts/teaming are strongly encouraged. It is anticipated that this program will require an unprecedented multi-disciplinary team that brings together expertise from traditionally disparate disciplines including information sciences and optical physics, in addition to domain expertise such as communications and imaging. A teaming website, http://www.sainc.com/InPho, will facilitate the formation of teams with the necessary expertise
DARPA seeks innovative proposals in the following four Technical Areas of Interests:
Imaging Thrust:
Technical Area One: Classical Imaging
New insights from the Classical Imaging community suggest that photon efficiencies approaching 1 bpp may be achievable. For example, it has recently been shown that compressive imaging techniques may be used to measure in a non-redundant (i.e., non-pixel) basis and thus may offer the potential for substantially increased photon efficiency. Computational imaging systems that provide improved image fidelity as compared with a conventional camera further support the notion of improved photon efficiency.
Extensions of this work to include information-theoretic analysis of compressive imaging provide additional evidence that photon efficiency can be drastically improved for task-specific measurement. Activities of interest within the Classical Imaging Technical Area therefore include, but are not limited to (a) imaging in extremely low-light environments, (b) compressive imaging, (c) novel image coding and priors, (d) information content of imagery, (e) image information carried by novel degrees of freedom, (f) 3D image information, (g) resource-constrained bounds on performance, etc.
The end-of-program goal for the Classical Imaging technical area is to demonstrate VIS/IR imaging reconstruction† with average photon efficiencies ≥ 1 bpp OR task-specific performance‡ ≥ 5 bpp. (See Table 1 for †, ‡ references)
Technical Area Two: Quantum Imaging
Recent demonstrations of novel Quantum Imaging techniques provide additional evidence for drastically increasing the information efficiency of individual photons. For example, ghost imaging experiments employing entangled photons enable the conveyance of image information within the correlation among multiple particles. The information capacity of these methods is currently unknown; however, multi-dimensional entanglement and/or incorporation of the compressive measurement paradigm are expected to enhance performance as well as photon information efficiency. Other quantum imaging systems are also of interest.
Single photon target detection/classification has been recently demonstrated and represents a task-specific measurement apparatus in which >1 bpp has been achieved. Activities of interest within the Quantum Imaging Technical Area therefore include, but are not limited to (a) novel entanglement for ghost imaging, (b) compressive ghost imaging, (c) single photon and entangled photon sources, (d) photon counting detector arrays, (e) single photon task-specific implementations, (f) quantum photonic memories, etc.
The end-of-program goal for the Quantum Imaging technical area is to demonstrate VIS/IR imaging reconstruction† with average photon efficiencies ≥ 1 bpp OR task-specific performance‡ ≥ 5 bpp. (See Table 1 for †, ‡ references)
Communications Thrust:
Technical Area Three: Classical Communications
New insights from the Classical Communication community also suggest that very high photon efficiencies may be achievable. For example, hybrid modulation formats such as PPM, quadrature phase shift keying (QPSK), quadrature amplitude modulation (QAM), and dense wavelength division multiplexing (DWDM) employing multiple photon degrees of freedom may be used to simultaneously increase both photon efficiency and spectral efficiency. Recent studies of orbital angular momentum (OAM) represent a case in point. This novel degree of freedom has been analyzed for both modulation and for multiplexing.
Predicted FSO capacity enhancements of 10x appear to be realistic even in the presence of moderate atmospheric turbulence. Activities of interest within the Classical Communication Technical Area therefore include, but are not limited to (a) Shannon limits of FSO channels incorporating multiple optical degrees of freedom, (b) encoding and decoding methods/limits for novel degrees of freedom such as OAM, (c) physical limits to information capacity of turbulent channels, (d) extensions to fiber channels, etc.
The end-of-program goal for the Classical Communications technical area is to demonstrate optical communication that simultaneously provides photon efficiencies of 10 bpp and spectral efficiencies of 5 bits/sec/Hz.
Technical Area Four: Quantum Communications
Research in novel Quantum Communication techniques provide further evidence for drastically increasing the information efficiency of individual photons while simultaneously providing quantum mechanical guarantees on security. For example, recent progress on multi-photon and/or multi-dimensional (e.g., OAM) entanglement has recently demonstrated increased secure data rates arising from the increased dimensionality of the underlying Hilbert space.
These high-dimensional systems have also been proposed to offer increased noise tolerance. For example, hybrid entanglement on continuous variables (e.g., energy/time or position/linear momentum) has been used to simultaneously demonstrate a large secure alphabet (e.g., 4 bits per photon) without sacrificing the fundamental security of the entangled channel. Activities of interest within the Quantum Communication Technical Area therefore include, but are not limited to (a) multi-photon and multi-dimensional entanglement, (b) hybrid entanglement on multiple photon degrees of freedom, (c) information optimization in the trade space defined by capacity and security, (d) entanglement preservation for turbulent propagation, (e) high-efficiency quantum state sorters, etc.
The end-of-program goal for the Quantum Communication technical area is to demonstrate optical communication that simultaneously provides photon efficiencies of 10 bpp and secure data rates of > 1 Gbps.
This program requires the formation of unprecedented multi-disciplinary teams that bring together expertise from traditionally disparate disciplines including information sciences and optical physics, in addition to domain expertise such as communications and imaging. The program is conceived in three phases of no more than 12 months each (base period, option 1, option 2), with the thrusts, technical areas, and end-of-program goals given in Table 1.
Model Broad Agency Announcement (BAA)
Broad Agency Announcement Information in a Photon Defense Sciences Office DARPA-BAA-10-19 Type: Other (Draft RFPs/RFIs, Responses to Questions, etc..)Posted Date: December 16, 2009 Model Broad Agency Announcement (BAA) DARPA-BAA-10-19.doc (354.00 Kb) Description: DARPA-BAA-10-1 Model Broad Agency Announcement (BAA) Appendix A and B.pdf (461.90 Kb) Description: DARPA-BAA-10-19 Appendix A and B Contracting Office Address: 3701 North Fairfax Drive Arlington, Virginia 22203-1714 Primary Point of Contact: Dr. Mark Neifeld mark.neifeld@darpa.mil Model Broad Agency Announcement (BAA) Points of Contact The Technical POC for this effort is Dr. Mark A. Neifeld. E-mail: DARPA-BAA-10-19@darpa.mil The BAA Administrator for this effort can be reached at: Electronic mail: DARPA-BAA-10-19@darpa.mi DARPA/DSO ATTN: DARPA-BAA-10-19 3701 North Fairfax Drive Arlington, VA 22203-1714 Email: DARPA-BAA-10-19@darpa.mil
Intelligent construction materials can boost energy efficiency and comfort. One of the disadvantages of the large-scale glass façades used in modern architecture is that they cause indoor temperatures to rise sharply in the summer. Air-conditioning already devours 15 percent of the total energy consumed in Europe. Researchers from the Fraunhofer Institute for Solar Energy Systems ISE teamed up with BASF to develop an environmentally-friendly alternative to air-conditioning systems. The team of researchers was nominated for the German Future Prize for their innovation comprising a microencapsulated latent heat storage material for construction materials.
More and more energy used for cooling
There is an urgent need for intelligent, low-energy alternatives to air-conditioning systems. Recent years have witnessed a steady increase in the amount of energy used to cool offices, commercial premises and housing. “We already use around 15 percent of our primary energy in Germany to generate energy for cooling,” reports Prof. Dr. Volker Wittwer, former deputy director of the Fraunhofer ISE. And the trend is upwards: while the amount of energy required each year for cooling in Europe stood at approximately 40 terawatt hours (TWh) in 1995, this figure is expected to triple by 2010, rising to more than 120 TWh per annum.
The ice cube effect
To produce a passive cooling effect, the researchers made use of phase change materials – known as PCMs – such as paraffin. During their transition from solid to liquid, PCMs absorb large quantities of energy, thereby preventing rooms from getting hotter. “It functions in a similar way to an ice cube: while the ice cube is melting the temperature remains at 0°C, and it doesn't rise above 0°C until everything has melted,” Wittwer explains, outlining the basic principle. Paraffins melt in the comfortable room temperature range that lies between 20°C and 26°C, in the course of which they absorb massive amounts of heat from their environment and prevent the temperature from increasing. At night, when the ambient temperature drops, the wax solidifies and the capsules release the heat they absorbed, making them ready to repeat the process the next day.
The right packaging
The principle is not a new one – in fact the idea of using phase change materials to control the temperature in buildings first emerged around 60 years ago. However, attempts to incorporate PCMs in construction materials were unsuccessful for many years. The breakthrough was finally achieved when Professor Wittwer came up with the idea of packing the wax into tiny casings and integrating it in conventional construction materials such as plaster, putty and lightweight panels
Collaboration between the research community and industry
Researchers from BASF took on the task of developing the right kind of encapsulation. “We were looking for ways of encapsulating the phase change materials in microscopic containers, or ‘microcapsules’,” explains Dr. rer. nat. Ekkehard Jahns from BASF. Microencapsulation offers a number of advantages: for example, the fact that the solid to liquid phase transition occurs in tiny spheres means that no wax can leak out, while the large surface areas and small volumes of the capsules means that the heat can quickly be absorbed into the material and the cold rapidly released. The diameter of the microcapsules is only around 5 μm, which is less than half the thickness of a human hair. “That makes it easier for us to incorporate the spheres in construction materials such as gypsum plaster, which can be applied to the wall in whatever form is required. The plaster does not look any different from conventional materials,” Jahns continues. “And there are plenty of other construction materials that are suitable for the integration of microcapsules, such as aerated cement blocks, plasterboard and wood products.”
Range of applications
The new construction materials are of particular interest for lightweight structures. A layer of PCM plaster approximately 1.5 cm thick has the same heat capacity as a concrete or brick wall. “That means we can reap the benefits of lightweight design while still storing heat,” states Dr.-Ing. Peter Schossig from ISE. “Modern phase change materials help us to go a long way towards solving the problem of rooms overheating, not only in offices but also in portable prefabricated buildings and older-style loft apartments. Newly developed construction materials containing microencapsulated latent heat storage materials can make a major contribution towards enhancing buildings, especially when it comes to increasing thermal comfort and making spaces more comfortable,” Schossig emphasizes.
Suitability for practical applications
Construction materials containing microencapsulated latent heat storage materials have already proven their suitability for practical applications. They have been incorporated in numerous buildings, including the Badenova building in Offenburg and the Haus der Gegenwart (Contemporary House) in Munich. Although the raw materials are available for purchase under the brand name Micronal PCMR, they are not yet available to buy in home improvement centers. “The explanations they require are still too elaborate at this point. The key is to integrate the new construction materials in the building's energy concept right from the planning stage,” Schossig stresses. But how long will these new building materials last? “The materials have a lifespan of between 30 and 50 years,” Schossig states. They also offer further advantages, such as the fact that they do not require maintenance and do not suffer damage as a result of hammering in nails or drilling holes.
Major benefits from tiny spheres
“PCMs offer enormous economic potential. By 2050 we are hoping to cut energy consumption by 50 percent, and much of these energy savings will have to come from buildings. To do this efficiently, we need new technologies, and our materials will make a major contribution towards developing them,” declares Professor Volker Wittwer with conviction.
