By focusing short laser pulses inside transparent solid materials, nonlinear optical effects can be induced and complex three-dimensional microstructures can be processed inside the material. Target materials include glasses, polymers, and silicon that is opaque to visible light but transparent to near-infrared light.
Glass is a typical brittle material, and is difficult to cut and plasticize. We have been studying the fabrication of miniature internal threads on transparent glass substrates using laser technology. “Miniature screw threads” is not only indicate small screws, but also the name of a standard (ISO 1501). We have succeeded in producing S0.5 and S0.4 female threads. Furthermore, we are conducting research to reduce cracks that occur during fabrication.
Hiroyuki Degawa, Noriaki Urano, and Shigeki Matsuo, Laser Fabrication of Miniature Internal Thread in Glass Substrate, Micromachines 8(2), 48 (2017). DOI: 10.3390/mi8020048
Water-Assisted Laser Drilling for Miniature Internal Thread in Glass and Evaluation of Its Strength, Reo Murakami, Hiroyuki Nakagawa, and Shigeki Matsuo, Journal of Laser Micro/Nanoengineering 12(3), 203-206 (2017). DOI: 10.2961/jlmn.2017.03.0005
Inscribing diffraction grating inside silicon substrate using a subnanosecond laser in one photon absorption wavelength, Kozo Sugimoto, Shigeki Matsuo, and Yoshiki Naoi, Scientific Reports 10, 21451 (2020). DOI: 10.1038/s41598-020-78564-z (Open Access)
Removal Processing inside PDMS by Short Pulse Laser, Katsuyuki Hayashi and Shigeki Matsuo, Journal of Laser Micro/Nanoengineering 12(2), 141-145 (2017). DOI: 10.2961/jlmn.2017.02.0016 (Open Access)
Laser-Induced Periodic Surface Structures (LIPSS), which is a periodic ridge-groove structure, can be produced on the surface of solid materials by irradiating a laser beam onto the material (in some cases, periodic patterns can be formed inside the material). Recently, it has been discovered that short pulse lasers can form structures with a much shorter period than the wavelength of the laser, and this has stimulated research. Our research is focused on pulse-by-pulse observation of the formation process of LIPSS, and on the formation of LIPSS using slightly longer (0.5 nanosecond) pulsed lasers.
The microstructures formed on solid surfaces by laser irradiation, including LIPSS, can control various surface properties such as wettability. We are also working on such research.
Pulse-by-pulse optical observation of laser-irradiated thin glass substrate using oil-immersion microscopy, Yuta Yanagisawa and Shigeki Matsuo, Japanese Journal of Applied Physics 61(1), 010901 (2022). DOI: 10.35848/1347-4065/ac4034 (Open Access)
Pulse-by-Pulse Optical Observation of Growth of Laser-Induced Periodic Surface Structure at Oblique Incidence, Kyosuke Shibata and Shigeki Matsuo, Journal of Laser Micro/Nanoengineering 15(2), 128-131 (2020). DOI: 10.2961/jlmn.2020.02.2009 (Open Access)
High-spatial-frequency periodic surface structures on steel substrate induced by subnanosecond laser pulses, Kyosuke Haruki Hikage, Nami Nosaka, and Shigeki Matsuo, Applied Physics Express 10(11), 112701 (2017). DOI: 10.7567/APEX.10.112701 (Open Access)
Subnanosecond-laser-induced periodic surface structures on prescratched silicon substrate, Motoharu Hongo and Shigeki Matsuo, Applied Physics Express 9(6), 062703 (2016). DOI: 10.7567/APEX.9.062703