• Home
  • Archive
  • Viewpoint on 'Science Communication'
    Viewpoint on 'Laser History'
    Viewpoint on 'EUV Lithography'
  • We welcome your comments, ideas and suggestions for upcoming features. Please, email them to editors@opfocus.org.

    OPFocus Archive

  • Volume 10 July-September 2010
    1. The optical trap and the speed of a Brownian particle. The focused green laser holds a Brownian particle. The scattering from the particle gives information about the instantaneous position of the particle and it is recorded 75 million times per second using a novel photodetector. The position increments tell show the researchers the instantaneous speed of the particle.Brownian SpeedcamThe optical trap and the speed of a Brownian particle. The focused green laser holds a Brownian particle. The scattering from the particle gives information about the instantaneous position of the particle and it is recorded 75 million times per second using a novel photodetector. The position increments tell show the researchers the instantaneous speed of the particle.Brownian particles, mind the speedcam! It is now possible to measure the instantaneous speed of a Brownian particle. Not only are these measurements of fundamental importance for statistical physics, they also open up new perspectives for the study of quantum systems.
    2. 3D tomography of a nanoparticle. The 3D shape of a nanoparticle can be reconstructed from many 2D SEM images of the same. Once the 3D morphology of the nanoparticle is known, its optical response can be calculated with the algorithm developed by the researchers at the National University of Córdoba.When Shape Really Matters3D tomography of a nanoparticle. The 3D shape of a nanoparticle can be reconstructed from many 2D SEM images of the same. Once the 3D morphology of the nanoparticle is known, its optical response can be calculated with the algorithm developed by the researchers at the National University of Córdoba.Particles in the nanoworld have mostly been modeled on unrealistically ideal shapes. A recent research takes advantage of a more complex and realistic model of the complex 3D shape of a nanoparticle.
    3. How does the momentum of a photon change when it interacts with matter? Does it increase or decrease? Both viewpoint are actually correct, depending on which momentum is being considered.Abraham vs. Minkowski 1-1How does the momentum of a photon change when it interacts with matter? Does it increase or decrease? Both viewpoint are actually correct, depending on which momentum is being considered.Does a photon gain or does it lose momentum when it enters a glass slab? Both may be the simple, yet ingenious answer to this centenary dilemma.
    4. Laser spectroscopy to see the proton size. A complex laser system is needed to perform the muonic hydrogen experiment. The picture shows frequency doubling optics transforming infrared to green light.Updating the Size of the Proton: Small Difference, Big ConsequenceLaser spectroscopy to see the proton size. A complex laser system is needed to perform the muonic hydrogen experiment. The picture shows frequency doubling optics transforming infrared to green light.The proton is one of the building blocks of matter and now latest studies suggest it is considerably smaller than previously measured. This is a result that may well challenge our current understanding of nature.
    5. Tumor imaging by Cerenkov Luminescence Tomography. Reconstructed Cerenkov luminescence tomography images fused with the computed tomography image of mouse. On the left, heart and bladder. On the right, cross-section revealing the presence of a tumor.Cerenkov Photons: A Cancer SearchlightTumor imaging by Cerenkov Luminescence Tomography. Reconstructed Cerenkov luminescence tomography images fused with the computed tomography image of mouse. On the left, heart and bladder. On the right, cross-section revealing the presence of a tumor.Millions of people fall victim to cancer every year. A great number of these lives could be saved if a simple, inexpensive tool for the early detection of cancer were available. Now, a new technique called Cerenkov luminescence tomography, looks likely to offer a ray of hope in that direction.
  • Volume 9 April-June 2010
    1. Reconstruction of a synapse. A 3D representation of the presynaptic neuron. The yellow spheres are the vesicles filled with neurotransmitter. The different types of filaments are in red and blue, the membranes of the presynaptic and postsynaptic neuron are in purple, and the synapse is in green. The postsynaptic neuron cotent is represented in dark yellow.Neurons, Freeze!Reconstruction of a synapse. A 3D representation of the presynaptic neuron. The yellow spheres are the vesicles filled with neurotransmitter. The different types of filaments are in red and blue, the membranes of the presynaptic and postsynaptic neuron are in purple, and the synapse is in green. The postsynaptic neuron cotent is represented in dark yellow.Neurons are the building block of the arguably most complex structure of the Universe: the human brain. Recent experiments show innovative ways to shock-freeze neurons while they are communicating with each other.
    2. Oil-water Illustration of spin gradient thermometry. At low temperatures, oil and water do not mix and form clearly separated phases with a tiny interface (left). At higher temperatures, the interface region is considerably larger, allowing one to deduce the temperature of the fluids (right).The Coolest ThermometerOil-water Illustration of spin gradient thermometry. At low temperatures, oil and water do not mix and form clearly separated phases with a tiny interface (left). At higher temperatures, the interface region is considerably larger, allowing one to deduce the temperature of the fluids (right).Temperature measurements are key in science and technology. Close to absolute zero, however, they are extremely difficult. A new method now allows the measuring of some of the coolest temperatures ever produced.

    3. THE VIEWPOINT by Alejandra Valencia

      LaserFest 2010. Year-long celebration of the 50<sup>th</sup> anniversary of the invention of the laser.Happy Birthday Laser!LaserFest 2010. Year-long celebration of the 50<sup>th</sup> anniversary of the invention of the laser.May 16, 1960. A day like many others, except, of course, for the fact that on this day the laser was born. A candy store owner, a photographer, and at least four American and two Russian scientists took part in the story that led to this accomplishment. This was a humble event, which could not foreshadow the future success of the newborn laser. This year the world celebrates the 50th birthday of the laser through an initiative jointly organized by various optics and photonics organizations: the LaserFest. Happy birthday laser!
    4. A random guess. Attempting to guess the random draw of the lottery is a matter of pure luck, even though, in principle, these draws can be described by deterministic laws of physics.Truly Random Results: You Can Bet on It! A random guess. Attempting to guess the random draw of the lottery is a matter of pure luck, even though, in principle, these draws can be described by deterministic laws of physics.True randomness can hardly ever be proved. However, latest experiments on quantum systems deliver truly random results — guaranteed!

    5. THE VIEWPOINT by Jean-luc Doumont

      How noise enters our communication. Claude Shannon’s communication model places the noise source exclusively on the channel [1]. In an oral presentation, however, much worse is the noise that comes from the transmitter (the speaker).Fighting the Noise in Your CommunicationHow noise enters our communication. Claude Shannon’s communication model places the noise source exclusively on the channel [1]. In an oral presentation, however, much worse is the noise that comes from the transmitter (the speaker).One of the best-known rules of telecommunication — maximize the signal-to-noise ratio — applies equally well to professional communication and can help us greatly improve our oral presentations, written documents, and graphs.
    6. Neutrophil tracks a pseudo-bacterium. A single neutrophil tracks a microbead as it mimics a slow-moving bacterium.In Pursuit of Bacteria: A Cat-and-Mouse GameNeutrophil tracks a pseudo-bacterium. A single neutrophil tracks a microbead as it mimics a slow-moving bacterium.Cells in the immune system seem to have a sixth sense for tracking down invasive bacteria. A new technique for manipulating single cells could revolutionize our understanding of their tactics and eventually lead to new strategies for mobilizing our body's defenses against disease.
    7. An x-ray view on a yeast cell. By employing lensless x-ray diffraction microscopy, this image of a group of yeast cells has been acquired with a resolution of ten nanometers -- approximately the length of 50 water molecules in a row. This is the highest resolution ever obtained with this method for biological samples. In this image the letters represent possible structures of the cell, such as vacuoles (V), mitochondria (M), and nucleus (N).Cells through X-RaysAn x-ray view on a yeast cell. By employing lensless x-ray diffraction microscopy, this image of a group of yeast cells has been acquired with a resolution of ten nanometers -- approximately the length of 50 water molecules in a row. This is the highest resolution ever obtained with this method for biological samples. In this image the letters represent possible structures of the cell, such as vacuoles (V), mitochondria (M), and nucleus (N).Thanks to their ability to see through solid objects, X-rays are one of the most powerful tools of modern medicine. They may soon enable us to see inside a single cell with a stunning resolution of ten nanometers.
  • Volume 8 January-March 2010
    1. The unit of the Bokode. A Bokode is composed of a tiny optical lens which hides a series of miniaturized 2D barcodes. Surprisingly, a camera taking an out-of-focus picture is able to create a sharp image of the Bokode.The Future of BarcodesThe unit of the Bokode. A Bokode is composed of a tiny optical lens which hides a series of miniaturized 2D barcodes. Surprisingly, a camera taking an out-of-focus picture is able to create a sharp image of the Bokode.Thanks to barcodes, computers can extract a lot of information on our everyday lives. A new technology by MIT, the Bokode, greatly enhances barcode technology, from interactive shopping to inexpensive motion capture.
    2. A photo-acoustic image. <i>In vivo</i> Multi Spectral Opto-acoustic Tomography (MSOT) image of a section of an adult zebrafish that expresses the fluorescent protein mCherry in its brain.Listen to the Light and See Deeper A photo-acoustic image. <i>In vivo</i> Multi Spectral Opto-acoustic Tomography (MSOT) image of a section of an adult zebrafish that expresses the fluorescent protein mCherry in its brain.Imaging fluorescent proteins in thick biological samples has always been a challenge. Now a new technique has harnessed the opto-acoustic effect in order to make deep tissue imaging easier for biologists.
    3. A terahertz tunable laser. In this artistic representation, the laser is the yellow wire, which is mounted on the grey support block. The electromagnetic field inside the laser reaches beyond the transversal dimensions of the wire, which makes it possible to influence the lasing frequency by moving objects close to the wire.A New Instrument for the Laser OrchestraA terahertz tunable laser. In this artistic representation, the laser is the yellow wire, which is mounted on the grey support block. The electromagnetic field inside the laser reaches beyond the transversal dimensions of the wire, which makes it possible to influence the lasing frequency by moving objects close to the wire.Laser physics and music share surprising analogies: lasers and flutes, for example, have been tuned in a very similar way until now. Recent experiments show that lasers can also be tuned in a way that does not find a counterpart in music, well not yet at least.
    4. Light. Is the speed of light changing over time? which evidence supports such hypotesis? and which could be the consequences?Is Light Slowing Down?Light. Is the speed of light changing over time? which evidence supports such hypotesis? and which could be the consequences?The speed of light is a universal constant — or is it? Some evidence seems to suggest it might actually be slowing down. Will we soon have to revise our cosmological beliefs?
    5. Dark pulse emission. Dark pulses appear as intensity dips in a continuous light emission, as opposed to bright pulses, which are intense bursts of light.The Dark Side of LasersDark pulse emission. Dark pulses appear as intensity dips in a continuous light emission, as opposed to bright pulses, which are intense bursts of light.Some scientific discoveries completely change how we look at things: it certainly was the case for Dirac’s theory on antimatter or Einstein’s theory of relativity. Now, our existing scientific ideas are set to change once more; new experiments show that laser theory should be extended to include dark pulse emission.
    6. Strains of hair. A laser removes the outer parts and creates an aerosol of the inner, clean constituents of the hair. Isotope analysis of the constituting atoms then reveals if a subject has traveled recently or not.Forensic Optics: Transforming a Hair into a Travel LogStrains of hair. A laser removes the outer parts and creates an aerosol of the inner, clean constituents of the hair. Isotope analysis of the constituting atoms then reveals if a subject has traveled recently or not.Solving crimes usually requires a lot of time and complicated investigations in order to find clear evidence. Now, it is possible to obtain information about a suspect's travel history simply by analyzing their hair.
    7. A twisted trap. An artist depiction of a nanoparticle optically trapped using a plasmonic vortex.Tiny Plasmonic WhirlpoolsA twisted trap. An artist depiction of a nanoparticle optically trapped using a plasmonic vortex.Scientists can twist light to create tiny typhoons on metal surfaces. Particles close to the light swirls can get trapped and pulled to the center of the whirlpool, like an autumn leaf is pulled to the center of a pond whirlpool.
  • Volume 7 October-December 2009
    1. Detecting surface plasmons as electrons. Schematic of the device that converts surface plasmons into an electric current. It consists of a silver nanowire along which the surface plasmons propagate, and a crossing germanium nanowire, that converts the surface plasmons to electron-hole pairs. A quantum dot can be used to launch the surface plasmons along the nanowire.Plasmon Harvesting: A Route to Plasmonic Circuitry Detecting surface plasmons as electrons. Schematic of the device that converts surface plasmons into an electric current. It consists of a silver nanowire along which the surface plasmons propagate, and a crossing germanium nanowire, that converts the surface plasmons to electron-hole pairs. A quantum dot can be used to launch the surface plasmons along the nanowire.What cannot be seen can often be felt, even in the case of physics. Invisible electromagnetic oscillations, known as surface plasmons, trapped inside a nanowire can now be detected by converting them into an electrical current.
    2. A molecular integrated circuit. An artistic representation of a fully optical circuit created on building bocks such as the single molecule optical transistor. In the black circle, a molecule is amplifying a light signal (yellow), exactly as a transistor does on electronic signals. The control over the amplification is given by a second light beam (green), which decides whatever the molecule is amplifying, attenuating or leaving the input signal unaltered.What a Molecular Transistor!A molecular integrated circuit. An artistic representation of a fully optical circuit created on building bocks such as the single molecule optical transistor. In the black circle, a molecule is amplifying a light signal (yellow), exactly as a transistor does on electronic signals. The control over the amplification is given by a second light beam (green), which decides whatever the molecule is amplifying, attenuating or leaving the input signal unaltered.How far can a single, tiny molecule go? Exceeding most people's imagination, researchers have shown that a single molecule can actually work as a transistor for photons.
    3. Pyrochlore lattice. The pyrochlore lattice is a crystalline structure formed by a network of corner-sharing tetrahedra. The magnetic moments reside on the vertices (red points) and always point towards the center of a tetrahedron. The minimum energy arrangement is the one in which two spins point into and two spins point out of each tetrahedron. The flip of a spin generates two magnetic charges that are then free to wander around the crystal independently of each other.Magnetic Break UpPyrochlore lattice. The pyrochlore lattice is a crystalline structure formed by a network of corner-sharing tetrahedra. The magnetic moments reside on the vertices (red points) and always point towards the center of a tetrahedron. The minimum energy arrangement is the one in which two spins point into and two spins point out of each tetrahedron. The flip of a spin generates two magnetic charges that are then free to wander around the crystal independently of each other.We usually think of the north and south magnetic poles as an inseparable couple. Experiments have now shown that under the appropriate conditions they can, in fact, break up.

    4. THE VIEWPOINT by Banqiu Wu & Ajay Kumar

      ASML Alpha Demo Tool. The sketch represents a developmental full-field EUVL scanner recently developed by ASML. The UV light source (based on a discharge-produced plasma DPP) is placed on the left. The generated UV light is directed by a series of Bragg mirrors to the reflective mask used to pattern the resist (on the right). The entire tool is kept in vacuum conditions to prevent the absorption of the UV light by the air.Extreme Ultraviolet Lithography: Towards the Next Generation of Integrated Circuits ASML Alpha Demo Tool. The sketch represents a developmental full-field EUVL scanner recently developed by ASML. The UV light source (based on a discharge-produced plasma DPP) is placed on the left. The generated UV light is directed by a series of Bragg mirrors to the reflective mask used to pattern the resist (on the right). The entire tool is kept in vacuum conditions to prevent the absorption of the UV light by the air.Lithography is the most challenging technology in the semiconductor industry. The most promising next generation lithography technology is extreme ultraviolet lithography (EUVL). EUVL was proposed long ago, in 1988, but its implementation has been postponed several times. Presently, most "showstoppers" are gone, but there are still several challenges that need to be addressed. The semiconductor industry is now getting ready to use EUVL in a pre-production phase, and EUVL might be implemented for 32 nm and 22 nm technological nodes. High volume manufacturing EUVL printers will be delivered to multiple end-users from 2010.
    5. How a spaser looks like. The spaser is formed by a gold core, which is surrounded by a glasslike shell filled with green dye molecule to create a sphere of 44 nanometers in diameter.The Smallest Laser EverHow a spaser looks like. The spaser is formed by a gold core, which is surrounded by a glasslike shell filled with green dye molecule to create a sphere of 44 nanometers in diameter.A year before the 50th anniversary of the invention of the laser, laser physicists present a new breakthrough: the nanolaser. It is the smallest laser ever, which makes a whole new range of applications in nanophotonics possible.
    6. The heart of the quantum computer. This is where the ions are physically stored and processed, surrounded by lasers, electronics and vacuum systems. Tiny trap segments located at the end of this bar confine and control the ions. Quantum information processing and cooling are done by shining laser beams onto the ions.The Dawn of Scalable Quantum ComputersThe heart of the quantum computer. This is where the ions are physically stored and processed, surrounded by lasers, electronics and vacuum systems. Tiny trap segments located at the end of this bar confine and control the ions. Quantum information processing and cooling are done by shining laser beams onto the ions.How close are we to the quantum computational revolution? Quantum computers promise drastic speedups for tackling the most complex mathematical problems. Nonetheless, current precursors of quantum computers cannot be scaled efficiently to reasonably sized systems. Now, researchers have realized a new setup that can be scaled more easily than ever before.
    7. A hollow-core photonic crystal fiber (PCF). Scanning electron microscope (SEM) image of the cross-section of a hollow-core PCF. Most of the light is transmitted in the hollow-core.Two Colors is Better than OneA hollow-core photonic crystal fiber (PCF). Scanning electron microscope (SEM) image of the cross-section of a hollow-core PCF. Most of the light is transmitted in the hollow-core.Standard optical fibers have revolutionized our lives. Now new perspectives can be envisioned for a new generation of photonic crystal fibers capable of transmitting two different colors at the same time.
    8. Check out my blood! <i>Ex vivo</i> stimulated emission image of microcapillaries of a mouse ear based on endogenous hemoglobin contrast (in red color), showing individual blood cells in the vessel network (inset) surrounding sebaceous glands (green overlay based on confocal reflectance).Colors Beyond the NoiseCheck out my blood! <i>Ex vivo</i> stimulated emission image of microcapillaries of a mouse ear based on endogenous hemoglobin contrast (in red color), showing individual blood cells in the vessel network (inset) surrounding sebaceous glands (green overlay based on confocal reflectance).We need eyes to see, but we need contrast to discern. A new technique for optical microscopy can now detect molecules even when their fluorescence is overwhelmed by background noise.
  • Volume 6 July-September 2009
    1. The five dimensions of optical storage. 18 different patterns recorded on the same space using three wavelengths (700 nm, 840 nm, and 980 nm) and two states of polarizations (vertical and horizontal) each.The Five Dimensions of Optical StorageThe five dimensions of optical storage. 18 different patterns recorded on the same space using three wavelengths (700 nm, 840 nm, and 980 nm) and two states of polarizations (vertical and horizontal) each.Can 300 DVDs be squeezed into a single optical disc? Ground breaking research in the field of surface plasmon physics seems to suggest so.
    2. The core of high refraction. The picture displays the core of the metamaterial with high index of refraction proposed by the researchers at Stanford University. Both high electric permittivity and magnetic permeability are needed in order to achieve a high refractive index in a metamaterial. Metallic inclusions allowing electric charge migration give a high permittivity, but usually a small permeability because of electric currents. The shape of the metallic inclusion needs to, therefore, be optimized in order to allow electric charges to move in non-loopy paths alone.Refractive Index: To the Limits and BeyondThe core of high refraction. The picture displays the core of the metamaterial with high index of refraction proposed by the researchers at Stanford University. Both high electric permittivity and magnetic permeability are needed in order to achieve a high refractive index in a metamaterial. Metallic inclusions allowing electric charge migration give a high permittivity, but usually a small permeability because of electric currents. The shape of the metallic inclusion needs to, therefore, be optimized in order to allow electric charges to move in non-loopy paths alone.Beyond what is naturally possible... metamaterials offer new unexplored opportunities to manipulate light. Researchers show the possibility to enhance the index of refraction of a material beyond natural limits.
    3. A zero mode waveguide used for real time sequencing of a DNA molecule. A single molecule of DNA bound to DNA polymerase is immobilized at the bottom of a zero mode waveguide, which is illuminated from below by laser light. The color of the emitted fluorescence indicates the present nucleotide being added to the chain.Decoding the Code of LifeA zero mode waveguide used for real time sequencing of a DNA molecule. A single molecule of DNA bound to DNA polymerase is immobilized at the bottom of a zero mode waveguide, which is illuminated from below by laser light. The color of the emitted fluorescence indicates the present nucleotide being added to the chain.Reading information stored by genes — also known as gene sequencing — is a vital task to the study of life itself. A radically new technology has set the stage for a revolution in the deciphering of DNA strands.
    4. Drawing with atoms. Quickly steering a laser on a BEC, it is possible to arrange the ultracold atoms in any shape. This technique can clear the way for new ultra-sensitive miniature sensors for atomic interactions. The Ultracold Laser ShowDrawing with atoms. Quickly steering a laser on a BEC, it is possible to arrange the ultracold atoms in any shape. This technique can clear the way for new ultra-sensitive miniature sensors for atomic interactions. In nightclubs and live concerts, figures or text are often outlined by quickly steering one single laser beam. The same principle has now been applied to drawing potentials onto ultracold gases: a new technique that could soon make its way into laboratories.
    5. A LEGO optical setup. Beam-expander system -- He-Ne laser, beam stopper, polarizer, 2 mirrors, concave lens, convex lens, screen -- built using standard LEGO components. The mount system is more compact than older ones and all optical parts are on rotating stages in order to make the adjustment of the optical axis easier. This is a well-known Galileo type beam expander (4X magnification). Inset: path of the beam.LEGO-OpticsA LEGO optical setup. Beam-expander system -- He-Ne laser, beam stopper, polarizer, 2 mirrors, concave lens, convex lens, screen -- built using standard LEGO components. The mount system is more compact than older ones and all optical parts are on rotating stages in order to make the adjustment of the optical axis easier. This is a well-known Galileo type beam expander (4X magnification). Inset: path of the beam.When I hear, I forget; when I see, I remember; but only when I do, do I understand. When it is not possible to let students play with expensive optical setups, LEGO comes into play.
    6. Negative refraction. The picture on the left shows how a spoon in a glass of water appears to break at the air-water interface, and then continues inside the liquid slightly shifted to one side, but still keeping the same orientation as in air -- left-to-right in this case. This optical illusion is due to the fact that the refractive index of water is different from the one of air -- still positive though, as in any other natural material. On the right, there is a basic illustration of what would happen by filling the glass with a liquid with a negative index of refraction: the orientation of the spoon inside the liquid would appear to be diametrically opposite to the spoon in the air, namely right-to-left instead of left-to-right.Magical MetamaterialsNegative refraction. The picture on the left shows how a spoon in a glass of water appears to break at the air-water interface, and then continues inside the liquid slightly shifted to one side, but still keeping the same orientation as in air -- left-to-right in this case. This optical illusion is due to the fact that the refractive index of water is different from the one of air -- still positive though, as in any other natural material. On the right, there is a basic illustration of what would happen by filling the glass with a liquid with a negative index of refraction: the orientation of the spoon inside the liquid would appear to be diametrically opposite to the spoon in the air, namely right-to-left instead of left-to-right.Magic lies in the beauty of a powerful illusion. This is what the latest achievements in optics seem to suggest; metamaterials are now able to optically turn one object into another.
    7. A contact lens with integrated circuitry. A researcher of the University of Washington holds a contact lens which embeds LEDs and other electrical components and which is manufactured using their newly developed self-assembly technique.Much More than a Contact LensA contact lens with integrated circuitry. A researcher of the University of Washington holds a contact lens which embeds LEDs and other electrical components and which is manufactured using their newly developed self-assembly technique.Super contact lenses which display background information onto your real world view seem like a gadget taken from the latest Spielberg movie. Thanks to a recently developed technique, this scenario may soon be real.
    8. Transparent ILED display. The transparent micro-ILED array is placed in front of the logo pattern of the University of Illinois at Urbana-Champaign (USA).A Brighter Future for LED Displays Transparent ILED display. The transparent micro-ILED array is placed in front of the logo pattern of the University of Illinois at Urbana-Champaign (USA).The displays of the future will be stretchable, twistable, deformable into any shape, and, perhaps more importantly, durable, efficient, and cheap. This is the promise of a new approach for manufacturing inorganic light emitting devices (ILEDs).
    9. A view through a METATOY. A sheet covered with tiny Dove prisms acts almost like a homogeneous surface and mimicks negative refraction in metamaterials. Here, a straight line perpendicular to the sheet appears bent into a hyperbola.From Fascination to RealityA view through a METATOY. A sheet covered with tiny Dove prisms acts almost like a homogeneous surface and mimicks negative refraction in metamaterials. Here, a straight line perpendicular to the sheet appears bent into a hyperbola.A deep fascination with the flight of birds inspired the invention of the airplane. A deep fascination with the stars inspired the invention of the telescope. What will fascination with metamaterials inspire?
  • Volume 5 April-June 2009
    1. Thermal nanoimage. By illuminating with a laser a surface where gold nanorods are unevenly placed, sharp temperature gradients can be created on microscopic scales. Here such gradients are measured on a 30x30 microns area. The temperature varies between 24º(black) and 31º (yellow). Inset: microscope image of the same area where the nanorod density can be seen.Thermal Images at the NanoscaleThermal nanoimage. By illuminating with a laser a surface where gold nanorods are unevenly placed, sharp temperature gradients can be created on microscopic scales. Here such gradients are measured on a 30x30 microns area. The temperature varies between 24º(black) and 31º (yellow). Inset: microscope image of the same area where the nanorod density can be seen.How would you measure the temperature of a nanoscopic object? How would you build a nano-thermometer? A new technique offers a solution.
    2. Looking inside the trap. The electron beam is scanned through the BEC very quickly. Since only few atoms are ionized during each run (left), this process is repeated 300 times to acquire an image of the spatial distribution of the atoms (right).Spying on Quantum GasesLooking inside the trap. The electron beam is scanned through the BEC very quickly. Since only few atoms are ionized during each run (left), this process is repeated 300 times to acquire an image of the spatial distribution of the atoms (right).A detective can only guess what mafia clans discuss inside their hideout. In a similar way, scientists usually only have indirect access to the behavior of trapped ultracold atomic gases. A novel microscopy technique now offers the possibility to directly observe what is happening inside the trap.
    3. Dynamically generated micro-channels. An arbitrary array of channels -- in this case the letters The Ice Age of MicrofluidicsDynamically generated micro-channels. An arbitrary array of channels -- in this case the letters The vision of shrinking a full lab into a chip is gradually becoming a reality. Now the possibility to dynamically generate microchannels with a laser spot in a slab of ice opens new possibilities towards a reconfigurable lab-on-a-chip.
    4. Brick by brick. Nanowalls with different shapes at the desired position built from the bottom-up, laying them down brick by brick.Another Brick in the NanowallBrick by brick. Nanowalls with different shapes at the desired position built from the bottom-up, laying them down brick by brick.Scientists, just as nano-architects would, are exploring different ways to design nanostructures with fine control over shape and position. A brand-new approach now allows one to build 2D nanowalls up by laying them down brick by brick.

    5. THE VIEWPOINT by Yaroslav Kartashov

      Possible applications of discrete solitons. Upper row: A nonlinear array network involving consecutive bends. The waveguide cross-sections are shown in green. A discrete soliton, shown in red, is set in motion in this system by appropriately tilting the beam. Computer simulations indicate that discrete soliton can successfully negotiate a sequence of bends. Lower row: An X-switching junction that uses two different discrete soliton families, signal (red) and blockers (blue). Unlike signal, which are highly mobile, blockers tend to retain their position after a collision event. After incoherent collision, the signal soliton is routed toward the lower branch, because of the presence of the two blockers at the entries of the respective pathways.Optical Lattice Solitons: Guiding and Routing Light at WillPossible applications of discrete solitons. Upper row: A nonlinear array network involving consecutive bends. The waveguide cross-sections are shown in green. A discrete soliton, shown in red, is set in motion in this system by appropriately tilting the beam. Computer simulations indicate that discrete soliton can successfully negotiate a sequence of bends. Lower row: An X-switching junction that uses two different discrete soliton families, signal (red) and blockers (blue). Unlike signal, which are highly mobile, blockers tend to retain their position after a collision event. After incoherent collision, the signal soliton is routed toward the lower branch, because of the presence of the two blockers at the entries of the respective pathways.Optical solitons are localized nonlinear excitations, which exist due to the mutual balance of diffraction and nonlinearity (in the case of spatial solitons) or dispersion and nonlinearity (in the case of temporal solitons). Moreover, they can propagate undistorted over indefinitely long distances. Being nonlinear objects, solitons may interact with each other, sometimes elastically, as if they were mechanical particles, or inelastically, when several solitons may merge together or give birth to new solitons after interaction. In the case of spatial solitons, the transverse modulation of the refractive index of the nonlinear material drastically affects their properties and affords new tools for the control of soliton propagation dynamics. Here, we review some possibilities for soliton control offered by periodic lattices and lattices produced by nondiffracting light beams.
    6. Teaming up in the right number. In rowing a given number of athletes join forces to compete. No deviation from this number could prevail during a competition. Similarly, in Efimov physics only certain numbers of bosons can bind together.Forging Quantum TeamsTeaming up in the right number. In rowing a given number of athletes join forces to compete. No deviation from this number could prevail during a competition. Similarly, in Efimov physics only certain numbers of bosons can bind together.A rowing team consists of a given number of athletes; adding or subtracting one would make it impossible for the team to compete. Recent experiments have shown that conditions exist under which quantum particles can also team up in a controlled number.
  • Volume 4 January-March 2009

    1. THE VIEWPOINT by Niek van Hulst

      STORM vs. Fluorescence Microscopy. Mitochondrial network in a mammalian cell visualized by 3D STORM. Conventional fluorescence image (left), 3D STORM image with colors denoting z location (middle) and single xy cross-section from the 3D STORM image (right).Many Photons get More out of DiffractionSTORM vs. Fluorescence Microscopy. Mitochondrial network in a mammalian cell visualized by 3D STORM. Conventional fluorescence image (left), 3D STORM image with colors denoting z location (middle) and single xy cross-section from the 3D STORM image (right).Nanoscopy, optical microscopy with 10-30 nm detail, has become a reality; in fact it has been chosen “Method of the year 2008” by Nature Methods [1]. We are all aware of the wave nature of light and the ensuing diffraction limit for resolution. So have the rules of physics been broken? What’s the trick and where’s the catch?
    2. Weak quantum questions. The researchers verified that a series of two weak quantum measuments can lead to restore the original state. The second measurement effectively undoes the effect of the first one. The picture shows the heart of the setup, where the qubits were generated and handled.Asking Twice, Yet Knowing NothingWeak quantum questions. The researchers verified that a series of two weak quantum measuments can lead to restore the original state. The second measurement effectively undoes the effect of the first one. The picture shows the heart of the setup, where the qubits were generated and handled.Have you ever been confused by an answer? Usually answers increase our knowledge, but latest experiments now show that asking two weak questions can leave us with less information than asking only one.
    3. An example of optical nanocircuit. Several nanostructures arranged next to each other at the nanoscale could become the present electronic circuits, allowing to rescale down radio-frequencies concepts such as the one of resistance (R), capacitance (C) and inductance (L).Twisting the Knob of LightAn example of optical nanocircuit. Several nanostructures arranged next to each other at the nanoscale could become the present electronic circuits, allowing to rescale down radio-frequencies concepts such as the one of resistance (R), capacitance (C) and inductance (L).Tuning nano-antennas may soon become as simple as tuning a radio to our favorite station — this is the new promise of nano-photonics.
    4. Experimental setup. A silica filament hanging in vacuum is observed while the light bends it.Pouring Oil on Troubled Light-MomentumExperimental setup. A silica filament hanging in vacuum is observed while the light bends it.What happens when light enters a medium? Does it gain or lose momentum? More than 100 years after its initial formulation, this dilemma is now being revitalized by new experiments.
    5. Over-squeezing. After a certain point, the squeezing does not improve the measurement anymore, but the opposite happens and more squeezing results in an increased uncertainty. The orange area on the surface of the sphere represents the polarization of the three-photon state. If the uncertainty for the polarization in one direction is squeezed hard, the uncertainty in the other direction wraps around the sphere.Squeezing the Most out of PhotonsOver-squeezing. After a certain point, the squeezing does not improve the measurement anymore, but the opposite happens and more squeezing results in an increased uncertainty. The orange area on the surface of the sphere represents the polarization of the three-photon state. If the uncertainty for the polarization in one direction is squeezed hard, the uncertainty in the other direction wraps around the sphere.Science relies on precise measurements. But how precise can a measurement be in principle? A new experiment shows a surprising new limit, together with a way around that limit.
    6. Nanotomography. The novel optical tomography technique allows the reconstruction of a 3D topographical map of the orientation of liquid crystal molecules by scanning a fiber tip inside the sample and collecting the polarized light transmitted by the liquid crystals.Images Worth a Thousand... Birefringent MoleculesNanotomography. The novel optical tomography technique allows the reconstruction of a 3D topographical map of the orientation of liquid crystal molecules by scanning a fiber tip inside the sample and collecting the polarized light transmitted by the liquid crystals.An image is worth a thousand words when describing complex physical phenomena such as temperature distributions, air flows and brain waves; a recently developed technique can now help us actually picture birefringent fluids at the nanoscale.
  • Volume 3 October-December 2008
    1. A quantum dot in an optical trap. A single quantum dot can be trapped and manipulated by an optical tweezers.A Nano-Firefly in the TrapA quantum dot in an optical trap. A single quantum dot can be trapped and manipulated by an optical tweezers.Fireflies emit pulses of light that allow them to be localized. Quantum dots behave in the same way albeit at the nanoscale. Now they can be manipulated using a relatively low power optical trap.
    2. Schematic of a UV laser diode. This schematic shows the 3D structure of the new laser diode by Hamamatsu Photonics. The dark blue layer is the active material which lases at 342 nanometers thanks to the absence of indium.An Ultraviolet Laser DiodeSchematic of a UV laser diode. This schematic shows the 3D structure of the new laser diode by Hamamatsu Photonics. The dark blue layer is the active material which lases at 342 nanometers thanks to the absence of indium.Laser diodes are the cheapest and most reliable lasers; nevertheless, they have hardly been able to emit in UV until now. This last barrier has now been broken, thus enabling potential and important applications, ranging from medicine to security issues.
    3. Generation of a pure sigle photon. The laser pulse (blue) enters a non-linear crystal that generates two photons (red, middle). A polarizing beam splitter is then used to separate the two photons of which one is used as a trigger (left) to indicate that there is another photon (right) ready to be used. Make Two, Keep OneGeneration of a pure sigle photon. The laser pulse (blue) enters a non-linear crystal that generates two photons (red, middle). A polarizing beam splitter is then used to separate the two photons of which one is used as a trigger (left) to indicate that there is another photon (right) ready to be used. To generate single photons remains a challenge, to have them in a pure, well-defined quantum state even more so. Now this is possible, thus paving the way for future quantum technologies and applications.
    4. The size of a US quarter. An exemplar of the new microscope developed at Caltech. In the picture, the comparison between the microscope and a US quarter can be seen.Honey, I Shrunk the Microscope!The size of a US quarter. An exemplar of the new microscope developed at Caltech. In the picture, the comparison between the microscope and a US quarter can be seen.Many of the everyday objects that we use are small enough to fit in our pockets. Take cell phones, with all their different accessories, for instance: are they also likely to come equipped with microscopes the size of a US quarter one day?
    5. Nerve Regeneration on a chip. An artist’s impression of a <i>C. elegans</i> worm immobilized in the microfluidic chamber, subjected to the process of nano-neurosurgery.Neurosurgery goes Nano inside a ChipNerve Regeneration on a chip. An artist’s impression of a <i>C. elegans</i> worm immobilized in the microfluidic chamber, subjected to the process of nano-neurosurgery.One of the standing goals of neuroscience is to understand neurons at a cellular level, in vivo. A recent development takes this goal one step further by enabling axon cuts and the study of nerve regeneration on individual neurons in live organisms.
    6. A knotted light beam. The complex structure of the lines of the electric field and of the magnetic field can be appreciated.Light's Ring-around-the-roseyA knotted light beam. The complex structure of the lines of the electric field and of the magnetic field can be appreciated.Can light travel only in straight lines? A new kind of light beam that travels along circles may soon provide an interesting twist to this question.
    7. Entangled coins. If two entangled coins were flipped, they would land on correlated sides: for example, whenever one landed on heads, the other one would land on tails. This kind of correlation is at the heart of quantum mechanics and cannot usually be seen in macroscopic objects. Now, Hartmann and Plenio have proposed a way to observe this correlation in membranes the size of a pinhead and, therefore, considerably larger than the atoms or photons that are mostly used in entanglement experiments.Visible and EntangledEntangled coins. If two entangled coins were flipped, they would land on correlated sides: for example, whenever one landed on heads, the other one would land on tails. This kind of correlation is at the heart of quantum mechanics and cannot usually be seen in macroscopic objects. Now, Hartmann and Plenio have proposed a way to observe this correlation in membranes the size of a pinhead and, therefore, considerably larger than the atoms or photons that are mostly used in entanglement experiments.Until recently, quantum behavior seemed to be the exclusive domain of tiny objects like atoms or electrons. However, entanglement of millimeter-sized membranes may soon come about, thus bringing quantum physics closer to our macroscopic world.
    8. Spooky action at a distance. How can two photons be correlated over a distance? If the photons communicated with each other, they would have to do so at an unbelievable speed, maybe instantaneously, researchers from Geneva conclude.The Spooky Physics of EntanglementSpooky action at a distance. How can two photons be correlated over a distance? If the photons communicated with each other, they would have to do so at an unbelievable speed, maybe instantaneously, researchers from Geneva conclude.In quantum physics, seemingly instantaneous correlations between distant objects can exist. Do these objects communicate? Probably not. However, if they do, their communication must be faster than the speed of light.
  • Volume 2 August-September 2008
    1. Schematic of a polymer blend. Microdroplets of a polymer are embedded in a matrix of a different polymer. Sometimes they escape.The Runaway PolymerSchematic of a polymer blend. Microdroplets of a polymer are embedded in a matrix of a different polymer. Sometimes they escape.Polymer blends are allies in our everyday lives, but they can also become our worst enemies, if the polymers mix too much. It is now possible to track down the polymers' behavior at the micrometer scale.
    2. Contracting heart cell. The image sequence shows the actual contraction of a cardiomyocyte, after it has been exposed to a series of femtosecond laser pulses.Cells in the Heart Dance to the Tune of LightContracting heart cell. The image sequence shows the actual contraction of a cardiomyocyte, after it has been exposed to a series of femtosecond laser pulses.The rhythmic beat of the heart keeps us alive. This beat is the result of an electrical mechanism, ingeniously put in place by nature, to control its cells. Surprisingly, ultrashort light pulses can do the same, virtually making these cells dance to the tune of light.
    3. Integrated flashes of light. A simple circuit, where three exciton-based transistors (EXOTs) have been integrated to perform some basic computation. Every EXOT, when processing signals, emits flashes of light as shown in the picture.Will Excitonic Circuits Change Our Lives?Integrated flashes of light. A simple circuit, where three exciton-based transistors (EXOTs) have been integrated to perform some basic computation. Every EXOT, when processing signals, emits flashes of light as shown in the picture.Transistors that process signals by emitting flashes of light: is this the milestone of a technological revolution in computation? Whether this scenario is science or fiction, only the future will tell.
    4. Measured cloud distribution of the earth. From outer space, clouds appear brighter than land and oceans because they reflect more light. Since the clouds are unevenly distributed in an earth-like planet, fluctuations in its brightness are expected.Checking the Weather of Alien PlanetsMeasured cloud distribution of the earth. From outer space, clouds appear brighter than land and oceans because they reflect more light. Since the clouds are unevenly distributed in an earth-like planet, fluctuations in its brightness are expected.Which planets in the universe are habitable? Check the weather! It is now possible to know if extra-solar planets have earth-like weather by analyzing the signature the weather leaves in the light scattered by these planets.
    5. The polymeric hummingbird’s wing. A polymeric cantilever containing photosensitive molecules (azobenzene, shown in the picture) starts to oscillate rapidly when exposed to light radiation. Just like the oscillations of a hummingbird’s wing, these oscillations occur at about thirty cycles per second (30 Hz).The Polymer and the Hummingbird’s WingThe polymeric hummingbird’s wing. A polymeric cantilever containing photosensitive molecules (azobenzene, shown in the picture) starts to oscillate rapidly when exposed to light radiation. Just like the oscillations of a hummingbird’s wing, these oscillations occur at about thirty cycles per second (30 Hz).Hummingbirds are unique and amazing birds: they can hover mid-air by rapidly flapping their wings. Even more amazing is the fact that an artificial polymer, which oscillates when exposed to laser light, can flutter like a hummingbird’s wing.
    6. The galloping race horse. By taking pictures of a process at different times and recombining the images, one can get a better understanding of a dynamical process. This picture, for example, proved that a race horse does take all feet off the ground while galloping. High-speed laser pulses can be used to image fast processes like electrons orbiting in molecules at different times.Towards Filming Chemical ReactionsThe galloping race horse. By taking pictures of a process at different times and recombining the images, one can get a better understanding of a dynamical process. This picture, for example, proved that a race horse does take all feet off the ground while galloping. High-speed laser pulses can be used to image fast processes like electrons orbiting in molecules at different times.High-speed cameras can film a bullet passing through an apple. Chemical reactions, however, are far too fast even for the best cameras. Attosecond physics promises new approaches to study and manipulate them.
  • Volume 1 June-July 2008
    1. Localized by disorder. Images of temporal evolution of the Bose-Einstein Condensate (BEC). Without disorder (top) the BEC expands freely in the non-confined direction, shown as vertical. With disorder (bottom) the BEC stays localized.The Disordered Quantum PrisonLocalized by disorder. Images of temporal evolution of the Bose-Einstein Condensate (BEC). Without disorder (top) the BEC expands freely in the non-confined direction, shown as vertical. With disorder (bottom) the BEC stays localized.Imagine a prison without walls, an open field where prisoners cannot leave simply because the field is not smooth. This is the idea behind Anderson Localization and has recently been observed in ultracold atomic gases.
    2. The plasmonic Ariadne's thread. Example of time signal generated by a plasmonic nanostructure following an external excitation. These signals reverted in time can be used to control light localization in the same nanostructure.Rewinding Plasmons Back in TimeThe plasmonic Ariadne's thread. Example of time signal generated by a plasmonic nanostructure following an external excitation. These signals reverted in time can be used to control light localization in the same nanostructure.Day-to-day life common sense often does not apply in science. But sometimes it works better than any other approach. Scouts know that retracing back clear markers on the way can avoid getting lost, the same principle has been recently proved to work in nanoplasmonics.
    3. Mantis shrimp (Gonodactylus smithii). Each of its eyes measures the six polarisation components that are precisely required.Super-Vision for Mr. ShrimpMantis shrimp (Gonodactylus smithii). Each of its eyes measures the six polarisation components that are precisely required.There is an invisible world illuminated by polarized light. A world that has been disclosed to us only by the technological advances of the last decades. Surprisingly, various Australian shrimps can see it.
    4. Microscope versus nanoscope. Diffraction-limited 3D focal spot in standard optical microscopy (<i>top</i>) compared to the 45 nm spherical one now achieved in optical nanoscopy (<i>bottom</i>).Nanoscopy: Shedding Light on LifeMicroscope versus nanoscope. Diffraction-limited 3D focal spot in standard optical microscopy (<i>top</i>) compared to the 45 nm spherical one now achieved in optical nanoscopy (<i>bottom</i>).Where traditional optical microscopy fails, a new tool, the nanoscope, overcomes the last barrier: the diffraction limit. It can explore the interior of cells in 3D, non-invasively, and with nanometric resolution.
    5. The heart of the optical clock. This part of the size of a fingernail contains the ion trap. Optical transitions of trapped aluminum and mercury ions serve as a reference, making measurements possible that are more accurate than ever before.Time to Test PhysicsThe heart of the optical clock. This part of the size of a fingernail contains the ion trap. Optical transitions of trapped aluminum and mercury ions serve as a reference, making measurements possible that are more accurate than ever before.How can we be sure about anything in nature? Without experiments, all physics is merely speculation. Optical clocks now allow us to test science with unprecedented accuracy, refining our understanding of the universe.
    6. A single-molecule fingerprint. TERS image of a single molecule about 10 nm wide.The Single Molecule Raman DetectivesA single-molecule fingerprint. TERS image of a single molecule about 10 nm wide.Who would you hire to localize a single molecule? A new detective is now available! A nano-lightning rod can do the job. It can act as a single-molecule fingerprint detective with an unprecedented spatial resolution up to 15 nanometers.
    7. A random laser flash of light. A random laser (red) shines light in all direction while it is pumped by a standard unidirectional laser (yellow).Random Lasers under ControlA random laser flash of light. A random laser (red) shines light in all direction while it is pumped by a standard unidirectional laser (yellow).Random lasers are generally difficult to control: they emit in every direction at once and in many different colors. Now, exploiting a fundamental physical phenomenon, it is possible to choose their color.
  • About
  • Contacts
  • Log in