Laser Applications in Microelectronic and Optoelectronic Manufacturing (LAMOM) XXX および Laser-based Micro- and Nanoprocessing (LBMP) XIX in SPIE. Photonics West 2025（サンフランシスコ、アメリカ）にて、宮地研が関わる研究成果を2件発表しました。宮地はLAMOMのCo-Chairです。

[13350-35] Poster presentation

Homogeneous periodic surface nanostructures formed by interference of square flattop femtosecond laser pulses

Author(s): Takemasa Sumimoto, Godai Miyaji, Tokyo Univ. of Agriculture and Technology (Japan)

28 January 2025 • 6:00 PM - 8:00 PM PST

We report on the formation of homogeneous LIPSS by using the two-step ablation process with a square flattop beam of femtosecond (fs) laser pulses. The Gaussian beam from a Yb fs laser system was converted to a square flattop beam by passing through a refractive beam shaper and a square metal mask. This beam was split into two beams with a diffraction optical element and focused on a titanium surface. Firstly, the interference of these two beams formed an interference pattern with a period of 1.8 µm through ablation. Next, the single beam was irradiated onto the surface to form a homogeneous nanostructure with a period of 450 nm in 25 μm square area.

[13351-5] Oral presentation

Surface nanostructuring by using circularly polarized GHz burst mode femtosecond laser pulses

Author(s): Shota Kawabata, RIKEN Ctr. for Advanced Photonics (Japan), Tokyo Univ. of Agriculture and Technology (Japan); Felix Sima, Institutul National pentru Fizica Laserilor, Plasmei si Radiatiei (Romania), RIKEN Ctr. for Advanced Photonics (Japan); Livia Elena Sima, Academia Romana (Romania); Stefana Orobeti, Institutul National pentru Fizica Laserilor, Plasmei si Radiatiei (Romania), Academia Romana (Romania); Shigeru Uchiyama, Takashi Isoshima, Kozunari Ozasa, Kotaro Obata, RIKEN Ctr. for Advanced Photonics (Japan); Mirai Hanzawa, Tokyo Univ. of Agriculture and Technology (Japan), RIKEN Ctr. for Advanced Photonics (Japan); Shi Bai, RIKEN Ctr. for Advanced Photonics (Japan); Godai Miyaji, Tokyo Univ. of Agriculture and Technology (Japan); Koji Sugioka, RIKEN Ctr. for Advanced Photonics (Japan)

27 January 2025 • 11:05 AM - 11:25 AM PST

Recently, there has been growing interest in GHz burst mode femtosecond laser pulses, which are characterized by a series of pulse (intra-pulse) trains with an extremely short pulse-to-pulse interval of several hundred picoseconds. The GHz burst is expected to be a superior tool to achieve high quality, high speed, and high efficiency as compared to the conventional irradiation scheme of fs laser pulses (single-pulse mode). We have revealed that linearly polarized GHz bursts can create lattice-like, 2D laser-induced periodic surface structures (LIPSS), exhibiting distinct geometries from the stripe-patterned 1D-LIPSS formed by the single-pulse mode fs laser pulse irradiation. It’s known that the circularly polarized single-pulse mode fs laser pulses can produce dot-patterned LIPSS on various solid materials. This study explores the potential of creating novel surface nanostructures by using the circularly polarized GHz burst mode fs laser processing and investigate their functionalities.

2025.01