Applied physicists at the Harvard
School of Engineering and Applied Sciences (SEAS) have demonstrated that they
can change the intensity, phase, and polarization of light rays using a
hologram-like design decorated with nanoscale structures. As a proof of
principle, the researchers have used it to create an unusual state of light
called a radially polarized beam, which -- because it can be focused very
tightly -- is important for applications like high-resolution lithography and
for trapping and manipulating tiny particles like viruses.
This is the first time a single,
simple device has been designed to control these three major properties of
light at once. Using these novel nanostructured holograms, they have converted
conventional, circularly polarized laser light into radially polarized beams at
wavelengths spanning the technologically important visible and near-infrared
light spectrum. Holograms find many applications in security, like the
holographic panels on credit cards and passports, and new digital
hologram-based data-storage methods are currently being designed to potentially
replace current systems.
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