David Kirkpatrick

May 27, 2010

Nanotech and optics

Very cool findings about light-activated nanoshells.

The release:

Optical Legos: Building nanoshell structures

Self-assembly method yields materials with unique optical properties

IMAGE: Heptamers containing seven nanoshells have unique optical properties.

Click here for more information.

HOUSTON — (May 27, 2010) — Scientists from four U.S. universities have created a way to use Rice University’s light-activated nanoshells as building blocks for 2-D and 3-D structures that could find use in chemical sensors, nanolasers and bizarre light-absorbing metamaterials. Much as a child might use Lego blocks to build 3-D models of complex buildings or vehicles, the scientists are using the new chemical self-assembly method to build complex structures that can trap, store and bend light.

The research appears in this week’s issue of the journal Science.

“We used the method to make a seven-nanoshell structure that creates a particular type of interference pattern called a Fano resonance,” said study co-author Peter Nordlander, professor of physics and astronomy at Rice. “These resonances arise from peculiar light wave interference effects, and they occur only in man-made materials. Because these heptamers are self-assembled, they are relatively easy to make, so this could have significant commercial implications.”

Because of the unique nature of Fano resonances, the new materials can trap light, store energy and bend light in bizarre ways that no natural material can. Nordlander said the new materials are ideally suited for making ultrasensitive biological and chemical sensors. He said they may also be useful in nanolasers and potentially in integrated photonic circuits that run off of light rather than electricity.

The research team was led by Harvard University applied physicist Federico Capasso and also included nanoshell inventor Naomi Halas, Rice’s Stanley C. Moore Professor in Electrical and Computer Engineering and professor of physics, chemistry and biomedical engineering.

Nordlander, the world’s leading theorist on nanoparticle plasmonics, had predicted in 2008 that a heptamer of nanoshells would produce Fano resonances. That paper spurred Capasso’s efforts to fabricate the structure, Nordlander said.

The new self-assembly method developed by Capasso’s team was also used to make magnetic three-nanoshell “trimers.” The optical properties of these are described in the Science paper, which also discusses how the self-assembly method could be used to build even more complex 3-D structures.

Nanoshells, the building blocks that were used in the new study, are about 20 times smaller than red blood cells. In form, they resemble malted milk balls, but they are coated with gold instead of chocolate, and their center is a sphere of glass. By varying the size of the glass center and the thickness of the gold shell, Halas can create nanoshells that interact with specific wavelengths of light.

“Nanoshells were already among the most versatile of all plasmonic nanoparticles, and this new self-assembly method for complex 2-D and 3-D structures simply adds to that,” said Halas, who has helped develop a number of biological applications for nanoshells, including diagnostic applications and a minimally invasive procedure for treating cancer.


Additional co-authors of the new study include Rice graduate students Kui Bao and Rizia Bardhan; Jonathan Fan and Vinothan Manoharan, both of Harvard; Chihhui Wu and Gennady Shvets, both of the University of Texas at Austin; and Jiming Bao of the University of Houston. The research was supported by the National Science Foundation, the Air Force Office of Scientific Research, the Department of Defense, the Robert A. Welch Foundation, the Department of Energy and Harvard University.

PhysOrg covers this story here.

October 1, 2009

Preview of upcoming Frontiers in Optics meeting

Lasers, 3D television and other cool stuff. Sounds like a fun event.

The release:

Powerful lasers, futuristic digital cameras, 3-D television and more

Highlights of Frontiers in Optics Meeting in San Jose, Oct. 11-15

WASHINGTON, Oct. 1—The latest technology in optics and lasers will be on display at the Optical Society’s (OSA) Annual Meeting, Frontiers in Optics (FiO), which takes place Oct. 11-15 at the Fairmont San Jose Hotel and the Sainte Claire Hotel in San Jose, Calif.

Information on free registration for reporters is contained at the end of this release. Research highlights of the meeting include:

  • A Special Symposium: The Future of 3-D Television
  • Laser Fusion and Exawatt Lasers
  • 1,001 Cameras See in Gigapixels
  • All That Glitters is Now Gold
  • Prehistoric Bear Diet Revealed by Laser Archaeology
  • Illumination-Aware Imaging


With 3-D movies helping to drive record box office revenues this spring and companies like Sony and Panasonic rolling out the first 3-D-enabled televisions, a timely special symposium titled “The Future of 3-D Display: The Marketplace and the Technology” will feature presentations on current and future technologies driving the 3-D revolution. Some highlights:

  • Rod Archer, vice president of Cinema Products at RealD Inc., will offer in his keynote speech an overview of 3-D movie systems already in use in some 1,700 screens around the world. Archer will discuss the current state-of-the-art, the challenges and the opportunities of 3-D cinema technologies.
  • Martin Banks of the University of California, Berkeley will discuss the difficulties of creating 3-D images free of perceptual distortions that don’t cause headaches, as well as his own solution, a temporally multiplexed volumetric display, in which a high-speed lens is switched on and off rapidly in synch with the image being displayed to create nearly correct focus cues.
  • Kevin Thompson of Optical Research Associates will lay out the future for the coming generation of head-worn displays, based on his work with Jannick Rolland of the University of Rochester’s Institute of Optics.
  • Masahiro Kawakita of NHK Science & Technology Research Labs, Japan will present an overview and a prototype of 3-D TV system based on integral photography technology.
  • Gregg Favalora of Acutality Systems will present an overview of one type of technology that moves away from glasses: volumetric displays, which project images onto high-speed rotating screens.
  • Brian Schowengerdt of the University of Washington will describe a volumetric display that scans multiple color-modulated light beams across the retina of the viewer to form images of virtual objects with correct focus cues.
  • Nasser Peyghambarian of the University of Arizona will present a prototype of a large-area 3-D updateable holographic display using photorefractive polymers. The rewritable polymer material is a significant breakthrough for holographic display technology.

The symposium is being organized by Hong Hua of the University of Arizona. For more information on the special symposium, see:http://www.frontiersinoptics.com/ConferenceProgram/SpecialSymposium/default.aspx#Futureof3DDisplay.


In the recent past, producing lasers with terawatt (a trillion watts) beams was impressive. Now petawatt (a thousand trillion watts, or 10^15 watts) lasers are the forefront of laser research. Some labs are even undertaking work toward achieving exawatt (10^18 watts) levels. Todd Ditmire at the University of Texas currently produces petawatt power through a process of chirping, in which a short light pulse (150 femtoseconds in duration) is stretched out in time. This longer pulse is amplified to higher energy and then re-compressed to its shorter duration, thus providing a modest amount of energy, 190 joules in a very tiny bundle.

Ditmire claims that his petawatt device has the highest power of any laser system now operating, even the one at the National Ignition Facility at the Lawrence Livermore National Lab, owing to the very short pulse-compression he and his colleagues use.

The main research use for the Texas Petawatt Laser, as it is called, has been to produce thermonuclear fusion; the laser light strikes a target where fusion of light nuclei occurs, releasing neutrons into the vicinity. These neutrons can themselves be used for doing research. The first results of this fusion experiment will be presented at this meeting. Other applications include the study of hot dense plasmas at pressures billions of time higher than atmospheric pressure and the creation of conditions for accelerating electrons to energies of billions of electron-volts.

Another figure of merit for a laser, in addition to power, is power density. The Texas device is capable of producing power densities exceeding 10^21 watts per square centimeter. At this level many novel interactions might become possible.

To get to exawatt powers, Ditmire hopes to combine largely-existing laser technology and his already-tested 100-femtosecond pulses with new laser glass materials that would allow amplification up to energies of 100 kilo-joules. Ditmire’s current energy level, approximately 100 joules, is typical of laser labs at or near the petawatt level, such as those in Oxford, England, Osaka, Japan and Rochester, N.Y. With support from the government and the research community, building an exawatt laser might take 10 years to achieve, Ditmire estimates. (Paper FTuK2, “The Texas Petawatt Laser and Technology Development toward an Exawatt Laser” is at 11 a.m. Tuesday, Oct. 13).


As manufacturers of consumer digital cameras compete in increments, adding one or two megapixels to their latest models, David Brady of Duke University is thinking much bigger. Working with the U.S. Department of Defense’s Defense Advanced Research Projects Agency, he is designing and building a camera that could achieve resolutions 1,000 or even 1 million times greater than the technology on the market today.

The goal of reaching giga- or terapixels, says Brady, is currently being held back by the difficulty of designing a spherical lens that will not distort small areas of a scene. His idea is not only to modify the shape of the camera lens — making it aspherical — but to link together thousands of microcameras behind the main lens. Each of these cameras would have its own lens optimized for a small portion of the field of view.

“Now, when you use a camera, you’re looking through a narrow soda straw,” says Brady. “These new cameras will be able to capture the full view of human vision.”

The final result of the three-year project should be a device about the size of a breadbox, though Brady hopes to scale the technology down to create a single-lens reflex camera with a resolution of 50 gigapixels. (Paper CWB2, “Multiscale Optical Systems” is at 2 p.m. Wednesday, Oct. 14).


In full sunlight at mid-day, gold objects are brilliant and richly colored. Put those same objects in a dark interior room with only fluorescent lamps, however, and they will look pale and slightly greenish — a problem arising from the inability of fluorescent lamps to render the optimal color temperature to reveal gold in its warmest light. That’s why museums and jewelry stores typically illuminate the gold objects in display cases with small incandescent bulbs, the only commercially-available lights that can emit soft yellow tones and warm color temperatures and render a true gold appearance.

Incandescent bulbs are a poor choice for other reasons, however. They are notoriously hot and can alter the temperature and humidity in display cases, potentially damaging priceless museum pieces. Besides that, the European Union is phasing out the sale of incandescent bulbs starting this fall (a similar phase-out will go into effect in the United States beginning in 2012).

Now Paul Michael Petersen and his colleagues at the Technical University of Denmark have designed an alternative, energy efficient and non-heating light source for gold objects. After they were contacted by curators at Rosenborg Castle in Copenhagen, which houses the Royal Danish Collection, Petersen and his colleagues created a novel LED designed specifically to illuminate gold. Combining commercially-available red, green, and blue LEDs with holographic diffusion, the new light can achieve a temperature and color rendering akin to incandescent bulbs — with 70 percent energy savings and without emitting excess heat. They have been tested in a few display cases, says Petersen, and the lights will soon be installed throughout the museum. (Paper JWC3, “A New LED Light Source for Display Cases” is at 12 p.m. Wednesday, Oct. 14).


Twenty-six thousand years ago, a brown bear living in what is now the Czech Republic died, leaving behind a tooth that has since become a fossil. Now a team of engineers has developed a way to figure out not only what it ate but its migration patterns using a laser instrument that could be modified to take out into the field.

The technique, called laser-induced breakdown spectroscopy (LIBS), is able to identify the chemical composition of a material — such a tooth — by penetrating miniscule samples with high-energy pulses of laser light. This laser turns each sample into plasma many times hotter than the surface of the sun. In this experiment, the light released as the plasma cooled revealed the composition of each part of the tooth.

By checking the ratio of different elements in the root of the tooth, the team determined that the bear ate mostly plants during the hotter parts of the year. The changes in these ratios over time revealed the bear’s migration patterns and a gradual shift in its living territory in one direction.

It’s a simple and fast technique, say the authors, with an unusually high resolution and the ability to scan a wide area of a sample. “The device could be modified to be taken out into the field,” says Josef Kaiser of the Brno University of Technology in the Czech Republic.

Next, the team hopes to use LIBS to solve the mystery of a cave full of dead snakes that died more than 1 million years ago — possibly from a disease — by analyzing the vertebrae left behind. (Paper JWC18, “Multielemental Mapping of Archaeological Samples by Laser-Induced Breakdown Spectroscopy (LIBS)” is at 12 p.m. Wednesday, Oct. 12).


Conventional imaging systems incorporate a light source for illuminating an object and a separate sensing device for recording the light rays scattered by the object. By using lenses and software, the recorded information can be turned into a proper image. Human vision is an ordinary process: the use of two eyes (and a powerful brain that processes visual information) provides human observers with a sense of depth perception. But how does a video camera attached to a robot “see” in three dimensions? Carnegie Mellon scientist Srinivasa Narasimhan believes that efficiently producing 3-D images for computer vision can best be addressed by thinking of a light source and sensor device as being equivalent. That is, they are dual parts of a single vision process.

For example, when a light illuminates a complicated subject, such as a fully-branching tree, many views of the object must be captured. This requires the camera to be moved, making it hard to find corresponding locations in different views. In Narasimhan’s approach, the camera and light constitute a single system. Since the light source can be moved without changing the corresponding points in the images, complex reconstruction problems can be solved easily for the first time. Another approach is to use a pixilated mask interposed at the light or camera to selectively remove certain light rays from the imaging process. With proper software, the resulting series of images can more efficiently render detailed 3-D vision information, especially when the object itself is moving.

Narasimhan calls this process alternatively illumination-aware imaging or imaging-aware illumination. He predicts it will be valuable for producing better robotic vision and rendering 3-D shapes in computer graphics. (Paper CtuD5, “Illuminating Cameras” is at 5:15 p.m. Tuesday, Oct. 13).



FiO 2009 is OSA’s 93rd Annual Meeting and is being held together with Laser Science XXV, the annual meeting of the American Physical Society (APS) Division of Laser Science (DLS). The two meetings unite the OSA and APS communities for five days of quality, cutting-edge presentations, fascinating invited speakers and a variety of special events spanning a broad range of topics in physics, biology and chemistry. The FiO 2009 conference will also offer a number of Short Courses designed to increase participants’ knowledge of a specific subject while offering the experience of insightful teachers. An exhibit floor featuring leading optics companies will further enhance the meeting.

Useful Links:

About OSA

Uniting more than 106,000 professionals from 134 countries, the Optical Society (OSA) brings together the global optics community through its programs and initiatives. Since 1916 OSA has worked to advance the common interests of the field, providing educational resources to the scientists, engineers and business leaders who work in the field by promoting the science of light and the advanced technologies made possible by optics and photonics. OSA publications, events, technical groups and programs foster optics knowledge and scientific collaboration among all those with an interest in optics and photonics. For more information, visit: www.osa.org.

May 11, 2009

EntreTech Forum coming May 19

Warm (this morning) from the inbox:

The EntreTech Forum Presents … PHOTONICS/OPTICS – Understanding the Latest Applications of Light-based Technologies in Medical, Consumer, Industrial, and Defense Sectors

BOSTON, May 11 /PRNewswire/ — On May 19th, The EntreTech Forum will bring together some of the region’s educators, researchers and entrepreneurs to focus on photonics/optics academic/commercial nexus of innovation, and to answer key questions around:

  —  understanding the local resource base for photonics-based innovation
  —  distilling the key drivers that define success or failure for
      early-stage research-driven photonics entrepreneurs
  —  defining for the audience what the next great ideas in
      photonics/optics technology will look like

Whether for treating disease, advancing solar energy cells or enhancing semiconductor performance, recent advances in photonics and optics have created myriad opportunities for entrepreneurs to break new ground across a tremendously wide spectrum of commercial activity. As ever, the Greater Boston area’s potent mix of university resources and entrepreneurial culture have made our region a leader in a new and constantly evolving technological field.

  Tuesday, May 19, 2009 6:30 – 9:30 p.m.

      The Enterprise Center at Foley Hoag,
      The Bay Colony Corporate Center
      1000 Winter St., Ste. 4000
      Waltham, MA
      Cost: $25 – public;  $10 – students & active military

For information, registration and directions visit our web site http://www.entretechforum.org/

  Pre-Registration Available Online http://theentretechforum.camp7.org/

  Directions & Map http://www.entretechforum.org/7_contact.htm

  — Moderator:
      Andrew Fairbairn, Managing Principal, Fairbairn Ventures

  — Panelists:
      Jonathan Rosen, Executive Director, Institute for Technology
       Entrepreneurship and Commercialization, BU School of Management

      Stephen Saylor, President & CEO, SiOnyx

      George Tegos, Instructor at MGH, Wellman Center for Photonics

  About The EntreTech Forum

The EntreTech Forum consists of moderated monthly panel discussions on emerging academic research and the commercialization of this technology. It was designed for those interested in technology innovation and marketing collaboration and networking with fellow entrepreneurs, business and government executives, investors, and technology researchers.

The technology-innovation presentations feature entrepreneurial and corporate accomplishments along commercialization pathways with discussions of tech transfer and technology incubation and research from universities, industry and government. The multi-disciplinary subjects of raising and utilizing different forms of capital, building alliances and structuring deals are included as part of the programming, and serve as tools for the entrepreneur and researcher to commercialize science and technology.

The EntreTech Forum is an affiliate of Northeastern University’s School of Technological Entrepreneurship (STE) and is directed by a governing board of business principals, investors, and researchers.

For information and directions visit our web site at http://www.entretechforum.org/

Source: The EntreTech Forum

Web Site:  http://www.entretechforum.org/

October 13, 2008

Black silicon

Filed under: Science, Technology — Tags: , , , , — David Kirkpatrick @ 2:25 am


From the link:

With the accidental discovery of “black silicon,” Harvard physicists may have very well changed the digital photography, solar power and night vision industries forever. What is black silicon, you say? Well, it’s just as it sounds. Black silicon. It’s what this revolutionary new material does that’s important, starting with light sensitivity. Early indications show black silicon is 100 to 500 times more sensitive to light than a traditional silicon wafer.

To create the special silicon, Harvard physicist Eric Mazur shined a super powerful laser onto a silicon wafer. The laser’s output briefly matches all the energy produced by the sun falling onto the Earth’s entire surface at a given moment in time. To spice the experiment up, he also had researchers apply sulfur hexafluoride, which the semiconductor industry uses to make etchings in silicon for circuitry. Seriously, he did this just for kicks and to secure more funding for an old project.

“I got tired of metals and was worrying that my Army funding would dry up,” he said. “I wrote the new direction into a research proposal without thinking much about it — I just wrote it in; I don’t know why,” he said.

(Hat tip: Wes)