Physicists map spiraling light to harness untapped data capacity

Aug 25, 2011

Physicists with the Institute of Ultrafast Spectroscopy and Lasers (IUSL) at The City College of New York have presented a new way to map spiraling light that could help harness untapped data channels in optical fibers. Increased bandwidth would ease the burden on fiber-optic telecommunications networks taxed by an ever-growing demand for audio, video and digital media. The new model, developed by graduate student Giovanni Milione, Professor Robert Alfano and colleagues, could even spur enhancements in quantum computing and other applications.

"People now can detect (light in) the ground channel, but this gives us a way to detect and measure a higher number of channels," says Mr. Milione. With such heavy traffic funneled through a single channel, there is great interest in exploiting others that can be occupied by complex forms of light, he explains.

The team published their work in the July 25 issue of . Mr. Milione will present it at the Optical Society of America's "Frontiers in Optics 2011" conference, October 16 - 20 in San Jose, Calif.

He was selected as a finalist in The Emil Wolf Outstanding Student Paper Competition, which highlights excellence and presentation skills of students at the conference. He and other finalists will be recognized at the OSA Foundation Chairman's Breakfast Wednesday, October 19.

Polarization is everything to a physicist tracking light in an optical fiber or laser. More than a way to cut glare with sunglasses, polarization refers to a specific direction and orientation of the light's movement and electric field — when it isn't going every which way as it does when emanating from a light bulb, for example.

"Being able to follow polarization and other changes as light travels gives you insight into the material it travels through, " explains Milione. This helps control the light and can essentially give a fingerprint of the material being analyzed.

Detecting the also lets users finely tune a laser. Such control can allow a laser to burn away one layer of material while leaving the other layers it passes through intact.

Until now, only the simplest form of light, the ground state, could be mapped and controlled. Multiple higher channels in an , which could be occupied by more complex light, were left sitting idle.

A globe-shaped model, called the Poincaré Sphere, has long been used to map such simple light. This light has peaks and troughs, like waves on the ocean, and moves or vibrates in "plane waves." One maps how light intersects the sphere in the same way one pinpoints a location on Earth using longitude and latitude.

But complex light moves with both spin and orbital angular momentum, more or less like the movement of our moon as it spins on its axis and orbits the Earth.

Such light twists like a tornado as it travels through space and takes the form of what are called vector beams and vortices. To map these vortices the researchers expanded the existing sphere to develop their Higher Order Poincaré Sphere (HOPS).

The team studies even more complex patterns of light, such as star-shaped forms. Their model uses the HOPS to reduce what could be pages of mathematics to single equations. These are the mathematical tools that will harness the complex light for use in technology.

"The sphere facilitates understanding, showing phase vortices are on poles and vector beams are on the equator," explains Milione. "It organizes the relationship between these vortices of ."

"This kind of organization on the higher level Poincaré Sphere could clear the path to a number of novel physics and engineering efforts such as and optical transitions; could greatly expand the sensitivity of spectroscopy and the complexity of computer cryptography; and might further push the boundaries what can be 'seen'," said Dr. Alfano.

Explore further: Seeking 'absolute zero', copper cube gets chillingly close

More information: G. Milione, H.I. Sztul, D.A. Nolan, and R.R. Alfano. Higher-Order Poincaré Sphere, Stokes Parameters, and the Angular Momentum of Light, Phys. Rev. Lett. 107, 053601 (2011) link.aps.org/doi/10.1103/PhysRevLett.107.053601

Provided by City College of New York

4.8 /5 (4 votes)

Related Stories

Physicists are first to 'squeeze' light to quantum limit

Jan 02, 2009

(PhysOrg.com) -- A team of University of Toronto physicists have demonstrated a new technique to squeeze light to the fundamental quantum limit, a finding that has potential applications for high-precision ...

Tying light in knots

Jan 17, 2010

(PhysOrg.com) -- The remarkable feat of tying light in knots has been achieved by a team of physicists working at the universities of Bristol, Glasgow and Southampton, UK, reports a paper in Nature Physics this w ...

Tiny lasers get a notch up

Jan 22, 2009

Tiny disk-shaped lasers as small as a speck of dust could one day beam information through optical computers. Unfortunately, a perfect disk will spray light out, not as a beam, but in all directions. New theoretical results, ...

Physicists rotate beams of light

Apr 05, 2011

Controlling the rotation of light – this amazing feat was accomplished at the Vienna University of Technology (TU Vienna), by means of a ultra thin semiconductor. This can be used to create a transistor ...

Recommended for you

Backpack physics: Smaller hikers carry heavier loads

21 hours ago

Hikers are generally advised that the weight of the packs they carry should correspond to their own size, with smaller individuals carrying lighter loads. Although petite backpackers might appreciate the ...

Extremely high-resolution magnetic resonance imaging

22 hours ago

For the first time, researchers have succeeded to detect a single hydrogen atom using magnetic resonance imaging, which signifies a huge increase in the technology's spatial resolution. In the future, single-atom ...

User comments : 0