High-performance geometric phase elements in silica glass

High-precision three-dimensional ultrafast laser direct nanostructuring of silica glass resulting in multi-layered space-variant dielectric metasurfaces embedded in volume is demonstrated. Continuous phase profiles of nearly any optical component are achieved solely by the means of geometric phase. Complex designs of halfwave retarders with 90% transmission at 532 nm and > 95% transmission at > 1 mu m, including polarization gratings with efficiency nearing 90% and computer generated holograms with a phase gradient of similar to 0.8 pi rad/mu m, were fabricated. A vortex half-wave retarder generating a single beam optical vortex with a tunable orbital angular momentum of up to +/- 100h is shown. The high damage threshold of silica elements enables the simultaneous optical manipulation of a large number of microobjects using high-power laser beams. Thus, the continuous control of torque without altering the intensity distribution was implemented in optical trapping demonstration with a total of 5 W average power, which is otherwise impossible with alternate beam shaping devices. In principle, the direct-write technique can be extended to any transparent material that supports laser assisted nanostructuring and can be effectively exploited for the integration of printed optics into multi-functional optoelectronic systems. (C) 2017 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license.