Currently, laser-induced structural modifications in optical materials have been an active field of research. In this paper, we reported structural modifications in the bulk of sapphire due to picosecond (ps) laser filamentation and analyzed the ionization dynamics of the filamentation. Numerical simulations uncovered that the high-intensity ps laser pulses generate plasma through multi-photon and avalanche ionizations that leads to the creation of two distinct types of structural changes in the material. The experimental bulk modifications consist of a void like structures surrounded by cracks which are followed by a submicrometer filamentary track. By increasing laser energy, the length of the damage and filamentary track appeared to increase. In addition, the transverse diameter of the damage zone increased due to the electron plasma produced by avalanche ionizations, but no increase in the filamentary zone diameter was observed with increasing laser energy.
Ionization behavior and dynamics of picosecond laser filamentation in sapphire
1. Ahmed F, Ahsan M S, Lee M S, Jun M B G. Near-field modification of femtosecond laser beam to enhance single-shot pulse filamentation in glass medium. Appl Phys A 114, 1161–1165 (2014).
2. Lanier T E, Gulley J R. Nonlinear space-time focusing and filamentation of annular femtosecond pulses in dielectrics. J Opt Soc Am B 33, 292–301 (2016).
3. Masselin P, le Coq D, Bychkov E, Lépine E, Lin C et al. Laser filamentation in chalcogenide glass. Proc SPIE 7993, 79931B (2011).
4. Yang Q, Ji L F, Xu B, Yan T Y, Wang W H et al. Picosecond laser microfabrication of infrared antireflective functional sur-face on As2Se3 glass. Opto-Electron Eng 44, 1200–1209 (2017).
5. Zhou R, Lin S D, Ding Y, Yang H, Ong K et al. Enhancement of laser ablation via interacting spatial double–pulse effect. Opto-Electron Adv 1, 180014 (2018).
6. Couairon A, Mysyrowicz A. Femtosecond filamentation in transparent media. Phys Rep 441, 47–189 (2007).
7. Galinis J, Tamo?auskas G, Gra?ulevi?iūt? I, Keblyt? V, Jukna V et al. Filamentation and supercontinuum generation in sol-id-state dielectric media with picosecond laser pulses. Phys Rev A 92, 1–5 (2015).
8. Liu Z, Lu X, Liu Q, Sun S, Li L et al. Ultraviolet conical emission produced by high-power femtosecond laser pulse in transparent media. Appl Phys B 108, 493–500 (2012).
9. Durand M, Jarnac A, Houard A, Liu Y, Grabielle S et al. Self-guided propagation of ultrashort laser pulses in the anomalous dispersion region of transparent solids: a new regime of filamentation. Phys Rev Lett 110, 115003 (2013).
10. Javaux Léger C, Mishchik K, Dematteo-Caulier O, Skupin S, Chimier B et al. Effects of burst mode on transparent materials processing. Proc SPIE 9351, 93510M (2015).
11. Ji L F, Amina, Yan T Y, Wang W H, Wang T R et al. Research progress of ultrafast laser industrial applications based on filamentation. Opto-Electron Eng 44, 851–861 (2017).
12. Gulley J R, Liao J X, Lanier T E. Plasma generation by ultrashort multi-chromatic pulses during nonlinear propagation. Proc SPIE 8972, 89720T (2014).
13. Gulley J R, Lanier T E. Model for ultrashort laser pulse-induced ionization dynamics in transparent solids. Phys Rev B 90, 155119 (2014).
14. Stuart B C, Feit M D, Herman S, Rubenchik A M, Shore B W et al. Optical ablation by high-power short-pulse lasers. J Opt Soc Am B 13, 459–468 (1996).
15. Ferris C. Theoretical modeling of laser-induced absorption phenomena in optical materials (University of Nebraska, Lin-coln, Nebraska, 2014).
16. Wang C W, Zhao Q Z, Qian J, Li Y B, Wang G D et al. Propagation of focused ultrashort pulse laser during micromachining of sapphire. Proc SPIE 9532, 95320O (2015).
17. Benayas A, Jaque D, McMillen B, Chen K P. Thermal stability of microstructural and optical modifications induced in sapphire by ultrafast laser filamentation. J Appl Phys 107, 033522 (2010).
18. DeSalvo R, Said A A, Hagan D J, Van Stryland E W, Sheik-Bahae M. Infrared to ultraviolet measurements of two-photon absorption and n2 in wide bandgap solids. IEEE J Quantum Electron 32, 1324–1333 (1996).
19. Arola E. Theoretical studies on multiphoton absorption of ultrashort laser pulses in sapphire. IEEE J Quantum Electron 50, 709–720 (2014).
20. Liu J M. Simple technique for measurements of pulsed Gaussian-beam spot sizes. Opt Express 7, 196–198 (1982).
21. Keldysh L V. Ionization in the field of a strong electromagnetic wave. Sov Phys JETP 20, 1307–1314 (1965).
22. Papazoglou D G, Zergioti I, Tzortzakis S, Sgouros G, Maravelias G et al. Sub-picosecond ultraviolet laser filamentation-induced bulk modifications in fused silica. Appl Phys A 81, 241–244 (2005).
23. Lotti A. Pulse shaping and ultrashort laser pulse filamentation for applications in extreme nonlinear optics (University of Insubria, Insubria, 2012).
24. Couairon A, Sudrie L, Franco M, Prade B, Mysyrowicz A. Filamentation and damage in fused silica induced by tightly focused femtosecond laser pulses. Phys Rev B 71, 125435 (2005).
25. Wu M T, Guo B, Zhao Q L, Fan R W, Dong Z W et al. The influence of the focus position on laser machining and laser micro-structuring monocrystalline diamond surface. Opt Lasers Eng 105, 60–67 (2018).
26. Saliminia A, Nguyen N T, Chin S L, Vallée R. The influence of self-focusing and filamentation on refractive index modifications in fused silica using intense femtosecond pulses. Opt Commun 241, 529–538 (2004).
27. Liao M S, Gao W Q, Cheng T L, Duan Z C, Xue X J et al. Filamentation and supercontinuum generation in tellurite glass. Proc SPIE 8621, 86211O (2013).
National Natural Science Foundation of China (51575013, 51275011) and National Key R & D Program of China (2018 YFB1107500)
引用本文： Amina, Ji L F, Yan T Y, Ma R. Ionization behavior and dynamics of picosecond laser filamentation in sapphire. Opto-Electron Adv 2, 190003 (2019).
上一篇：Enhanced organic solar cell performance: Multiple surface plasmon resonance and incorporation of silver nanodisks into a grating-structure electrode
Crafting Interior Holes on Chemically Strengthened Thin Glass Based on Ultrafast Laser Ablation and Thermo-Shock Crack Propagations
Sensors and Actuators A: Physical, 2019