Transmissive metasurface quarter-wave plates for few-femtosecond pulses at deep ultraviolet wavelengths

We design, fabricate, and measure transmissive dielectric metasurfaces made of high-aspect ratio, wide band-gap oxide materials to achieve circularly polarized laser beams at deep ultraviolet wavelengths. We optimize the design towards a broadband quarter-wave plate for ultrafast (few femtosecond) pulses while being resistant to high-power lasers. Our metasurfaces are designed to be on thin silicon nitride membranes to minimize group delay dispersion from the substrate. We also measure the damage threshold of our fabricated metasurfaces to evaluate their efficacy and robustness to high intense lasers. Our work could pave the way towards further development of transmissive DUV optical elements with customized functionalities and their integration into more complex systems for spatiotemporal shaping of DUV pulses.