By passing polarized light through a voxel imprinted in silica glass, 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. |
Researchers
at the Optoelectronics Research Centre (ORC) at the University of
Southampton, UK, have developed new nano-structured glass optical
elements which have applications in optical manipulation and may
significantly reduce the cost of medical imaging.
In a paper published in Applied Physics Letters,
a team led by Professor Peter Kazansky at the ORC describe how they
have used nano-structures to develop new monolithic glass space-variant
polarization converters. These millimeter-sized devices generate
whirlpools of light enabling a variety of functions: precise laser
material processing, optical manipulation of atom-sized objects,
ultra-high resolution imaging and, potentially, table-top particle
accelerators. They have since found that the technology can be developed
further for optical recording.
According
to the researchers, at sufficient intensities, ultra-short laser pulses
can be used to imprint tiny dots (like 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 advantage of this approach over existing methods for microscopy is that it is 20 times cheaper and it is compact.
“Before
this we had to use a spatial light modulator based on liquid crystal
which cost about 20,000,” said Professor Peter Kazansky. “Instead we
have just put a tiny device into the optical beam and we get the same
result.”
Since
publication of the paper in May this year, 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 Lithuanian company Altechna to introduce this technology to the market.
Radially polarized optical vortex converter created by femtosecond laser nanostructuring of glass
