By Patricia Daukantas

I can’t let my coverage of FiO/LS end without mentioning the wonderful talk that OSA Honorary Member Arthur Ashkin gave at the special symposium organized in his honor.

Ashkin, now 88 years old and retired from Alcatel-Lucent/Bell Laboratories (U.S.A.), pioneered the notion of moving microparticles with laser light, back in the days when lasers were the new thing on the lab bench. His work formed the basis for optical tweezers and, eventually, the atom-cooling and laser-trapping work that garnered three other OSA Honorary Members their Nobel Prize in 1997.

In his autobiographical speech, Ashkin--who still has traces of the accent of his native Brooklyn, N.Y.--showed his warm and sometimes mildly self-deprecating humor. Yes, he said, he holds degrees from “all these fancy schools” like Columbia and Cornell universities, but it took him seven years just to get his bachelor’s degree.

That wasn’t entirely of his own doing. As he entered Columbia, World War II was starting and the university, whose physics department had people like Sidney Millman, Willis Lamb and Polykarp Kusch, founded a radiation laboratory with, as Ashkin put it, “all this new equipment free from the government.” Millman taught the new undergraduate about magnetrons – “glass, brass and sealing wax” – and then Ashkin got drafted at age 19.

“I’m a sophomore, how important can I be to the war effort?” Ashkin asked rhetorically. But the folks at Columbia got him into the Army’s enlisted reserve, so that he could work as a staff member, and he eventually built a megawatt magnetron.

Once Ashkin got to Cornell as a graduate student, he said, he took no solid-state physics or optics courses. “All I took was nuclear physics because there were all these guys from Los Alamos [the Manhattan Project, which built the first nuclear weapons],” he said. He took the first quantum mechanics class taught by the then-future Nobel Prize winner Richard P. Feynman. Ashkin added: “The stories I could tell, if I had the time…”

Once hired at Bell Labs, he was told he could do anything he wanted to do, but he still ended up working on microwave tubes for a while. “At Bell Labs they wanted you to do great work, but you had to find your own way,” he said.

In the late 1960s, Ashkin attended a talk about “runners” and “bouncers,” or tiny balls moving around due to heating. That got him thinking about radiation pressure, and he started thinking about moving even tinier particles with the light from laser beams, and then experimenting in earnest.

By the time Ashkin was writing his first paper on the subject, he was wondering whether the laser beams could trap atoms, molecules and microscopic living things. “So I put all that into the paper and got credit for it,” he added. His first experiments with trying to move bacteria around killed them--he dubbed it “opticution”--but eventually he and his colleagues learned how to keep them alive while moving them with infrared beams.

You can read more about Ashkin’s pioneering efforts in a March 2010 feature article in OPN.

Like a good entertainer, Ashkin knows how to leave his audiences wanting more. He wound up his talk by saying that during his 15-year retirement, he has been experimenting with solar power, and he thinks he has found away of getting energy from the Sun more cheaply than burning fossil fuels.“I’m writing a paper for Science, and if I tell you about it they won’t publish it,” he concluded. “So stay tuned.”

The Newest OSA Honorary Member

At its meeting during FiO/LS, the OSA board of directors selected James P. Gordon as the Society’s newest Honorary Member. Regular readers of OPN may recall his article for the May 2010 issue of OPN--the special “Lasers at 50” issue--in which he described his work on the first maser with another OSA Honorary Member, Charles H. Townes.

2010-10 October, Applied optics, Biomedical optics, Frontiers in Optics, Optics history fio, optics history, optical manipulation, optical tweezers, optical history, lasers

By Patricia Daukantas

To celebrate Charles Kao’s share of the 2009 Nobel Prize in physics for his pioneering fiber optics work, the FiO/LS conference brought together industrial and academic researchers for a special symposium on optical communications.

OSA’s 1995 president, Tingye Li, kicked off the conference with a historical overview of the field that, as a longtime researcher at AT&T/Bell Laboratories (U.S.A.), he was well-positioned to witness and influence.

Noting that Kao’s Nobel came exactly 100 years after Guglielmo Marconi and Karl Ferdinand Braun won it for “wireless telegraphy,” Li said that the award to Kao fulfilled the original intent of the prize to recognize innovations that benefit human society. He listed Kao’s three great innovations:

• Conceptualizing optical fiber communications by proposing glass fibers as a viable data-transmitting medium;
• Having the insight that silica would be the low-loss medium of choice for future communications and rigorously verifying that experimentally, showing his understanding of the fundamental physics behind the application; and
• Traveling around the world to spread his “gospel” of optical communications until the industry began to take it seriously.

Li noted the characteristic engineering language of Kao’s first paper on the subject in 1966. He wrote that silica fibers may have a “large information capacity,” when the correct adjectival phrase might have turned out to be “astronomically large.” After all, the capacity of optical fiber systems has multiplied 1-million-fold since Corning Inc. developed the first truly low-loss fiber in 1970 and the telecom industry started its early field trials shortly thereafter.

Other symposium speakers included Peter Schultz of Corning (U.S.A.), David Payne of the University of Southampton (England) and Hiroshi Takahashi of NTT Photonics Laboratories (Japan). (Shultz recently wrote an article for OPN about the development of the first low-loss optical fibers.)

Current OSA director-at-large Neal Bergano of Tyco Electronics (U.S.A.) capped off the symposium by describing the types of cable armor, repeaters and large ships that go into building the planet’s undersea communications infrastructure. Hundreds of thousands of kilometers of optical cables now stretch across ocean and sea floors, either as direct links or branch-and-trunk networks. They certainly transmit digital data for far less cost than the $5 per word for telegrams sent via the first permanent transatlantic telegraphic cable in the late 1860s.

More FiO/LS Coverage

Today (Thursday) is the final day of the conference, with a number of invited talks on intriguing topics.

I haven’t forgotten the OSA Student Chapter members whose competition I photographed -- watch for coverage in an upcoming blog post. Also, I wrote about OSA Fellow Michal Lipson’s talk at the MWOSA gathering in OPN’s Bright Futures Blog.

Fiber optics, FiO/LS, Frontiers in Optics, Optics history, OSA optics, photonics, Optics & Photonics News, Charles Kao, OSA, The Optical Society, Frontiers in Optics, optical communications, fiber optics, Patricia Daukantas

By Patricia Daukantas, OPN Contributing Writer

LaserFest--the yearlong celebration of the 50th anniversary of the first laser--is not over yet. At this year’s FiO/LS meeting, LaserFest has a strong presence in the exhibit hall.

Since arriving in Rochester (N.Y., U.S.A.), I’ve been hearing a lot about the Laser Maze, so by the time the exhibit hall opened yesterday morning, I could hardly wait to try it. The University of Rochester’s student chapter of OSA developed the maze with a grant from the LaserFest program. Previously the students had set it up at the Rochester Museum and Science Center, but they moved it over to the OSA meeting for the enjoyment of attendees.

The premise of the Laser Maze will be familiar to anyone who has ever seen one of those bank-robbery or jewel-heist movies. A laser and a light sensor make up part of a complete circuit. Interrupt the laser beam and the circuit breaks.

In this case, the circuit was powering a small music player, so breaking the beam stopped the music (instead of setting off an alarm like in the movies). The laser beam bounced side to side several times off parallel mirrors close to the floor, so the maze walker had to step through the gaps between the reflected beams.

Of course, in the movies the audience sees the laser beams from the side, thanks to either smoke or computer-generated effects. No such luck with the Laser Maze, however. The LaserFest people had a small theatrical “smoke” machine, but due to a combination of the bright ceiling lights and the ventilation in the exhibit hall, the particles did not linger long in the air. Thus, the maze walker had to look for tiny red dots on the mirrors and imagine where the beam might have gone, based on equal angles of incidence and reflection.

Since I didn’t want to embarrass anyone else, I had someone take photos of me trying to step through the maze.Here I’m starting off on the right foot.

I’m home safe after figuring out the first beam path.

Another step, probably higher than it needs to be.

Dang! I just nicked that last horizontal beam!

To make the maze even more challenging, the Rochester chapter set up a second set of reflecting beams and mirrors … vertically. Technically, to complete the maze, one had to get through both the horizontal and vertical sections without interrupting the recorded music. However, I probably would have had to slide myself on the floor to get through that maze, and I wasn’t feeling quite that acrobatic.

OSA Student Chapter Competition 2010

At last year’s FiO/LS, OSA student chapters built miniature solar-powered cars and raced them. This year, they were given a different challenge: to create an educational tabletop exhibit to teach young people about one or more principles of optics.

Yesterday I visited several of the chapters’ tables, but since the competition is continuing into today, I’ll write up more details for tomorrow’s blog entry.

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By Patricia Daukantas

Halloween is the season of ghosts, goblins and vampires … so why not add some spooky quantum entanglements to the mix? On a cloudy, damp morning in Rochester (N.Y., U.S.A.), the plenary speakers at OSA’s 94th annual meeting, Frontiers in Optics, took the audience on a tour of Bell inequalities, wild biomolecules and other scientific treats.

This year’s Ives Medalist, OSA 2007 President Joe Eberly, used elementary trigonometric identities (remember those?) to demonstrate a seeming contradiction in a thought experiment about a polarizing interferometer. Eberly, a longtime professor at the University of Rochester, solved the conundrum by showing that the photons were entangled in what is now known as a Bell state.

Measuring degrees of photon entanglement is one of Eberly’s recent interests. He noted that Erwin Schrödinger introduced the notion of entanglement in 1935 -- and, 75 years later, scientists still don’t have a lot of quantitative answers about it. This is “a guarantee of permanent employment for a physicist,” he said, generating a ripple of chuckles among the audience.

One of the two winners of the American Physical Society’s Arthur M. Schawlow Prize, Henry Kapteyn of JILA (University of Colorado, U.S.A.), paid homage to the award’s namesake. “It was clear he liked to point lasers at things and blow them up, and that’s mostly what we do,” he said. Fortunately, most of the high-energy (and soft-X-ray) lasers he talked about haven’t exploded, and he predicted that there are excellent prospects for generating hard X-ray laser beams from tabletop devices in the near future. His wife and co-prize-winner, Margaret Murnane of JILA, will speak at tonight’s APS Laser Science banquet.

Plenary speaker Steven Block, a professor of physics and biology at Stanford University (U.S.A.), took the audience on a tour of “riboswitches,” non-coding messenger RNA strands that control gene expression by changing their structure when they selectively bind to a signal molecule. In evolutionary terms, this is probably the earliest form of molecular control at the cellular level, but it was poorly understood until scientists could start manipulating the molecules with optical tweezers. (Attendees of CLEO/QELS 2010 in May might remember Block’s blues mandolin performance.)

The final plenary speaker, Alain Aspect of the Institut d’Optique (France), gave a history lesson on the Hanbury Brown and Twiss interferometry experiment of the mid-1950s and its relevance to modern-day quantum optics.

Checking the Efficacy of Breast-Cancer Therapy

Can oncologists deduce the efficacy of breast-cancer treatment as early as one day after the start of chemotherapy? According to Albert Cerussi of the Beckman Laser Institute (U.S.A.), this can happen, thanks to a technique called diffuse optical spectroscopic imaging (DOSI).

Traditional “adjuvant therapy” for breast cancer calls for surgery first, followed by a round of chemotherapy. Oncologists are now moving to “neo-adjuvant therapy,” in which the chemo comes first -- making it even more important to monitor the patient’s response to the powerful drugs.

DOSI works in the near-infrared window of 650 to 1,000 nm; those wavelengths penetrate tissue relatively well, although the photons take a “random walk” through the tissue (hence the “diffuse” part of the imaging). Instead of getting the black-and-white patterns of a traditional mammogram, DOSI provides spectral information about tumor biomarkers such as oxygenated and deoxygenated hemoglobin.

Researchers first studied DOSI at the midpoint of chemotherapy, when oncologists usually assess the patient and decide whether to switch therapies. But the researchers from Beckman and the Chao Family Comprehensive Cancer Center (both part of the University of California at Irvine) found that they could detect changes in the biomarkers one week and even one day after the start of chemotherapy.

According to Cerussi, scientists are even studying whether the technique could predict whether chemo will help a particular patient even before the treatment starts, but they are still trying to understand the biological process behind that. In the near future, researchers will look for additional biomarkers, shrink the size of the equipment, and join a clinical trial involving four other cancer centers.

(Note to readers of OPN’s Twitter feed, @OPNmagazine: Cerussi’s talk was the one I chose out of eight simultaneous invited talks at the start of the afternoon sessions. It was a tough call -- the other topics included luminescent solar concentrators, laser refractive surgery for cataracts and long-term monitoring of buried fiber-optic cables.)

Industrial Physics Forum

This event, sponsored by the Corporate Associates of both OSA and the American Institute of Physics, drew large crowds to several talks -- particularly the one by quantum cascade laser pioneer Federico Capasso of Harvard University. On Monday, the forum covered a range of biomedical and environmental applications of lasers.

An Earth-observing lidar satellite called CALIPSO (for “Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations”) has been in orbit since April 2006, and Carl Weimer (Ball Aerospace, U.S.A.) reviewed its ongoing engineering and science results.

As I described in an OPN article last year, CALIPSO is part of an “A-Train” of environmental satellites in the same orbit, with roughly 15 minutes of spacing between them. Its dual-wavelength (532 and 1,064 nm) lasers collect data in a 70-m-wide “curtain” from ground level to about 40 km altitude.

So far, the satellite has collected 6.6 terabytes of data from 2.6 billion laser shots, Weimer said. Its estimated particle sizes within cloud distributions provide important input for scientists’ models of global atmospheric circulation.

The Industrial Physics Forum is concluding this morning with sessions on lasers’ applications in metrology and other “frontiers of physics” areas.

The Day Ahead: Tuesday

This afternoon, brand-new OSA Honorary Member Arthur Ashkin will speak first at a symposium honoring his pioneering work with optical tweezers. The FiO/LS exhibit hall will open, and OSA student chapters will kick off their lesson plan competition. Two other events of particular interest to young professionals are a public-policy forum and the Minorities and Women in OSA (MWOSA) tea. Finally, we’ll all learn who won the OSA officer elections for 2011.

2010-10 October, Applied optics, Biomedical optics, FiO/LS, Lasers OSA, university of rochester, fio, biomedical optics, industrial applications, Patricia Daukantas, the Optical Society, quantum entanglement, CALIPSO, LaserFest