講演情報
[7p-P06-8]Efficient Generation of an Annular-Shaped Radially Polarized Beam
for Laser Nano Processing of a Dielectric Surface
〇(M1)Wenqi Wang1,2, Yuuki Uesugi1, Yuichi Kozawa1 (1.IMRAM, Tohoku Univ., 2.Grad. Sch. of Eng., Tohoku Univ.)
キーワード：
Radially polarized beam、Beam shaping、laser processing
A radially polarized beam has a superior ability to produce a small focal spot compared to conventional, linearly or circularly polarized beams, which has the potential to improve the spatial resolution in ultrafast laser processing. This property stems from the generation of the longitudinal electric field under high numerical aperture (NA) conditions. However, the presence of material interfaces generally diminishes the longitudinal field because of the boundary condition. The introduction of an annular amplitude mask for a radially polarized beam, which masks the low NA components, is a common approach to enhance the longitudinal electric field at the focus. However, the thinner annular width suffers from a significant reduction in light use efficiency of the mask, limiting the usability of the annular mask in laser processing. Here, we propose a novel beam shaping technique that can efficiently generate a thin annular-shaped radially polarized beam, suitable for laser nano-processing.