Novel Z polarizer benefits laser micromachining

Ashley N. Paddock, ashley.paddock@photonics.com

A new laser writing technique has been used to produce Z polarizers, or radial polarization converters, that can be used for laser machining, microscopy, optical tweezers and Raman spectroscopy systems.

Workshop of Photonics has collaborated with researchers at the Optoelectronics Research Centre at the University of Southampton in the UK to develop the direct laser writing technique. Z polarization gives a laser beam a smaller spot size and enables the same machining properties in all directions. The special configuration lambda plate can convert circular polarization to radial or azimuthal, or it can create an optical vortex of higher-level topological charge.

“Scientists at the University of Southampton discovered that it is possible to form controllable birefringent features inside of transparent materials,” said Evladas Pabreza, research and development sales architect at the workshop. They accomplish this using a femtosecond laser for direct laser writing.

A new radial polarization converter, formed at the center of a fused-silica substrate, holds promise for laser machining, microscopy, optical tweezers and Raman spectroscopy systems. Courtesy of Workshop of Photonics.

The Workshop of Photonics and Optoelectronics Research Centre laboratories expect to prove the advantages of Z polarizers in laser micromachining, such as decreased spot size and uniformity of light-material interaction, regardless of machining direction.

“For the moment, we have shown just the first application of said direct laser writing technique – the radial polarization converter,” Pabreza said. “The ‘mystical’ radial (azimuthal) polarization still is not very well explored, since there was no affordable yet high-power resistant means for generating it.”

He said, however, that the laboratories are exploring two areas that could have significant impact: laser micromachining and fiber laser amplifiers. Future embodiments may lead to the design and production of multiple optical elements within a single piece of glass, which would contribute significantly to integrated optics.

Workshop of Photonics has begun looking for integrators and end users in the fields of laser machining, microscopy and optical tweezers. Testing units are now available, with small-scale production of the devices scheduled for mid-autumn. The university has applied for a patent application and has appointed Altechna R&D Ltd. as its exclusive commercialization partner.