Modification characteristics of filamentary traces induced by loosely focused picosecond laser in sapphire. Issue 10 (July 2020)

• Record Type: Journal Article
• Authors: Yan, Tianyang; Ji, Lingfei; Ma, Rui; Amina, ; Lin, Zhenyuan
• Is Part Of: Ceramics international. Volume 46:Issue 10(2020)Part B
• Page Start: 16074
• Page End: 16079
• Publication Date: 2020-07
• Subjects: Picosecond laser -- Filamentation -- Sapphire -- Modification -- Phase transition; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2020.03.159
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: The ability of loosely focused picosecond laser to induce filamentation (4.8 times the Rayleigh length) in sapphire was confirmed. The morphology and microstructure of the filamentary traces under typical pulse energy were studied, in which the colorful birefringence phenomenon and damage defects were detected in sapphire. Irreversible ceramic-like polycrystalline microstructures were formed in filamentary traces, and the phase transition from α -Al2 O3 to γ -Al2 O3 directly reflected the thermal effect of picosecond laser filamentation. According to the filamentary characteristics, a continuous filamentary channel with a uniform diameter of 33 μm and a length of 7443 μm was obtained by gradually raising the focal position. The research provides first-hand information for the high throughput micro-cutting, micro drilling and thin slicing of sapphire based on ultrafast laser non-linear effects. Highlights: The ability of loosely focused picosecond laser only focused by normal industrial focus lens with lower numerical aperture to induce filamentation in sapphire is confirmed. Two types of sapphire modification induced by picosecond laser filamentation are determined, and the microstructure, phase change and residual stress characteristics of the filamentary traces are analyzed. The irreversible ceramic-like polycrystalline microstructures and phase transition from α-Al2 O3 to γ-Al2 O3 in traces directly reflects the thermal effect of picosecond laser filamentation. Picosecond laser filamentation modification is caused by the combination of non-linear ionization and thermal effect. A continuous filamentary channel with ultra-large aspect ratio of 255 indicates a new direction of filament-induced laser processing in sapphire-like transparent materials.