In a study published online May 16, 2011, the journal Applied Physics Letters, a team led by Prof. Peter Kazansky from the University of Southampton’s (UK) Optoelectronics Research Center, described how they have used nanostructures to develop new monolithic glass space-variant polarization converters. These millimeter-sized devices generate “whirlpools” of light, thereby enabling precise laser material processing, optical manipulation of atom-sized objects, ultra-high resolution imaging, and potentially, tabletop particle accelerators. They have since found that the technology can be additionally developed for optical recording.

According to the researchers, at sufficient intensities, ultra-short laser pulses can be used to imprint tiny dots (like three-dimensional [3D] pixels) called voxels in glass. Their previous research showed that lasers with fixed polarization produce voxels consisting of a periodic arrangement of ultra-thin (tens of nanometers) planes. By passing polarized light through such a voxel imprinted in silica glass, the researchers observed that it travels differently depending on the polarization orientation of the light. This ‘form birefringence’ phenomenon is the basis of their new polarization converter.

The benefit of this approach over existing methods for microscopy is that it is 20 times less expensive and it is compact. “Before this we had to use a spatial light modulator based on liquid crystal, which cost about GBP 20,000,” said Prof. Kazansky. “Instead, we have just put a tiny device into the optical beam and we get the same result.”

Since publication of the study, the researchers have developed this technology further and adapted it for a five-dimensional optical recording. “We have improved the quality and fabrication time and we have developed this five-dimensional memory, which means that data can be stored on the glass and last forever,” said Martynas Beresna, lead researcher for the project. “No one has ever done this before.”

The researchers are working with the company Altechna (Vilnius, Lithuania) to introduce this technology to the market.

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University of Southampton
Altechna