Terahertz pulses generate two types of laser-induced periodic surface structures on phase change material Ge2Sb2Te5.
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| Title: | Terahertz pulses generate two types of laser-induced periodic surface structures on phase change material Ge |
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| Authors: | Wang, You Wei1 (AUTHOR), Yang, Zihao1 (AUTHOR), Kato, Kosaku1 (AUTHOR), Agulto, Verdad C.1 (AUTHOR), Phan, Thanh Nhat Khoa1 (AUTHOR), Makino, Kotaro2 (AUTHOR), Tominaga, Junji3 (AUTHOR), Isoyama, Goro4 (AUTHOR), Nakajima, Makoto1 (AUTHOR) nakajima.makoto.ile@osaka-u.ac.jp |
| Source: | Applied Physics A: Materials Science & Processing. Jul2025, Vol. 131 Issue 7, p1-7. 7p. |
| Subjects: | Submillimeter waves, Phase change materials, Physical sciences, Surface structure, Refractive index |
| Abstract: | This study investigates the formation of two types of laser-induced periodic surface structures (LIPSS) on amorphous Ge2Sb2Te5 (GST) using terahertz free-electron laser (THz-FEL) irradiation. The THz pulses used in this study consist of a macro pulse containing 150 micro pulses, each with a duration of 2 ps. The central wavelength λ of the THz radiation is 75 μm. By exposing GST to THz-FEL pulses at fluences up to 35 J/cm2, two distinct periodic structures were observed: low spatial frequency LIPSS (LSFL) and high spatial frequency LIPSS (HSFL). The LSFL formed parallel to the laser's polarization direction with a period of approximately λ/4.5. The HSFL, with a period λ/18, formed perpendicular to the polarization near the ablation edges. The periods of the generated HSFL and LSFL are 4 μm and 16 μm, respectively, and can be observed with an optical microscope. The period of the LSFL is generally consistent with λ/n (where n is the material's refractive index), which is the approximate value expected based on previous reports in the optical region. This work contributes to a deeper understanding of LIPSS formation mechanisms under long-wavelength terahertz irradiation and suggests pathways for fine-tuned surface structuring applications using THz-FEL. [ABSTRACT FROM AUTHOR] |
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| Database: | Engineering Source |
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| Abstract: | This study investigates the formation of two types of laser-induced periodic surface structures (LIPSS) on amorphous Ge2Sb2Te5 (GST) using terahertz free-electron laser (THz-FEL) irradiation. The THz pulses used in this study consist of a macro pulse containing 150 micro pulses, each with a duration of 2 ps. The central wavelength λ of the THz radiation is 75 μm. By exposing GST to THz-FEL pulses at fluences up to 35 J/cm2, two distinct periodic structures were observed: low spatial frequency LIPSS (LSFL) and high spatial frequency LIPSS (HSFL). The LSFL formed parallel to the laser's polarization direction with a period of approximately λ/4.5. The HSFL, with a period λ/18, formed perpendicular to the polarization near the ablation edges. The periods of the generated HSFL and LSFL are 4 μm and 16 μm, respectively, and can be observed with an optical microscope. The period of the LSFL is generally consistent with λ/n (where n is the material's refractive index), which is the approximate value expected based on previous reports in the optical region. This work contributes to a deeper understanding of LIPSS formation mechanisms under long-wavelength terahertz irradiation and suggests pathways for fine-tuned surface structuring applications using THz-FEL. [ABSTRACT FROM AUTHOR] |
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| ISSN: | 09478396 |
| DOI: | 10.1007/s00339-025-08679-5 |
