New Way of Observing Light May Boost Info Content

md_seymour observes: "Today's Astronomy Picture of the Day from NASA has a description and image of light that can twist as well as spin, based on research from Miles Padgett and Johannes Courtial of the University of Glasgow. They and their colleagues have apparently been able to sort individual photons by their orbital angular momentum. Since this characteristic of the photon is able to take on an infinite number of values, it may be possible to pack much more information into a light beam."

Comments

No.

[Anonymous Coward]

No, they're different.

Take a beam of circularly-polarized light (without orbital-angular-momentum), freeze time in your imagination, and look at the E-field vectors along the beam. The E-field vectors all point in the same direction. Over time they rotate around the beam axis -- that's what circular polarization means -- but the E-field-vectors are always aligned along the entire length of the beam.

Now instead imagine a beam of light with orbital-angular-momentum, and again freeze the beam in your imagination. Now the E-field vectors make a helix along the beam.

You get circularly polarized light by passing a beam through a polarizer and quarter-wave plate. You get light with orbital angular momentum by spinning the light source around the beam axis.

A bit more information from Scientific American

[UnknowingFool]

There's a short article about this property of light in this month's edition of Scientific American. Apparently this propery isn't new but rather largely ignored.