With high hardness, high thermal and chemical stability and excellent optical performance, hard materials exhibit great potential applications in various fields, especially in harsh conditions. Femtosecond laser ablation has the capability to fabricate three-dimensional micro/nanostructures in hard materials. However, the low efficiency, low precision and high surface roughness are the main stumbling blocks for femtosecond laser processing of hard materials. So far, etching-assisted femtosecond laser modification has demonstrated to be the efficient strategy to solve the above problems when processing hard materials, including wet etching and dry etching. In this review, femtosecond laser modification that would influence the etching selectivity is introduced. The fundamental and recent applications of the two kinds of etching assisted femtosecond laser modification technologies are summarized. In addition, the challenges and application prospects of these technologies are discussed.
[Opto-Electron Adv, 2019, 2(9)]Etching-assisted femtosecond laser modification of hard materials
First published at:Sep 20, 2019
1. Kang I S, Kim J S, Kang M C, Lee K Y. Tool condition and machined surface monitoring for micro-lens array fabrication in mechanical machining. J Mater Process Tech 201, 585–589 (2008).
2. Toros A, Kiss M, Graziosi T, Sattari H, Gallo P et al. Precision micro-mechanical components in single crystal diamond by deep reactive ion etching. Microsyst Nanoeng 4, 12 (2018).
3. Chen T H, Fardel R, Arnold C B. Ultrafast z-scanning for high-efficiency laser micro-machining. Light Sci Appl 7, 17181 (2018).
4. Wang J N, Liu Y Q, Zhang Y L, Feng J, Wang H et al. Wearable superhydrophobic elastomer skin with switchable wettability. Adv Funct Mater 28, 1800625 (2018).
5. Brasselet E, Malinauskas M, ?ukauskas A, Juodkazis S. Photopolymerized microscopic vortex beam generators: Precise delivery of optical orbital angular momentum. Appl Phys Lett 97, 211108 (2010).
6. Jiang L, Wang A D, Li B, Cui T H, Lu Y F. Electrons dynamics control by shaping femtosecond laser pulses in mi-cro/nanofabrication: modeling, method, measurement and application. Light Sci Appl 7, 17134 (2018).
7. Travitzky N, Bonet A, Dermeik B, Fey T, Filbert-Demut I et al. Additive Manufacturing of Ceramic-Based Materials. Adv Eng Mater 16, 729–754 (2014).
8. Liao Y, Ni J L, Qiao L L, Huang M, Bellouard Y et al. High-fidelity visualization of formation of volume nanogratings in porous glass by femtosecond laser irradiation. Optica 2, 329–334 (2015).
9. Zhang Q M, Yu H Y, Barbiero M, Wang B K, Gu M. Artificial neural networks enabled by nanophotonics. Light Sci Appl 8, 42 (2019).
10. Xie X Z, Zhou C X, Wei X, Hu W, Ren Q L. Laser machining of transparent brittle materials: from machining strategies to applications. Opto-Electron Adv 2, 180017 (2019).
11. Jiang H B, Zhang Y L, Liu Y, Fu X Y, Li Y F et al. Bioinspired few-layer graphene prepared by chemical vapor deposition on femtosecond laser-structured Cu foil. Laser Photonics Rev 10, 441–450 (2016).
12. Xu B, Du W Q, Li J W, Hu Y L, Yang L et al. High efficiency integration of three-dimensional functional microdevices inside a microfluidic chip by using femtosecond laser multifoci parallel microfabrication. Sci Rep 6, 19989 (2016).
13. Xu B, Hu W J, Du W Q, Hu Y L, Zhang C C et al. Arch-like microsorters with multi-modal and clogging-improved filtering functions by using femtosecond laser multifocal parallel microfabrication. Opt Express 25, 16739–16753 (2017).
14. Xu B, Shi Y, Lao Z X, Ni J C, Li G Q et al. Real-time two-photon lithography in controlled flow to create a single-microparticle array and particle-cluster array for optofluidic imaging. Lab Chip 18, 442–450 (2018).
15. Serien D, Sugioka K. Fabrication of three-dimensional proteinaceous micro- and nano-structures by femtosecond laser cross-linking. Opto-Electron Adv 1, 180008 (2018).
16. Pham T A, Kim D P, Lim T W, Park S H, Yang D Y et al. Three-dimensional SiCN ceramic microstructures via nano-stereolithography of inorganic polymer photoresists. Adv Funct Mater 16, 1235–1241 (2006).
17. Cao Y Y, Takeyasu N, Tanaka T, Duan X M, Kawata S. 3D metallic nanostructure fabrication by surfactant-assisted multiphoton-induced reduction. Small 5, 1144–1148 (2009).
18. Lan B, Hong M H, Ye K D, Wang Z B, Chong T C. Laser microfabrication of glass substrates by pocket scanning. In Fourth International Symposium on Laser Precision Micro-fabrication (SPIE, 2003). https://doi.org/10.1117/12.540725.
19. Hong M H, Sugioka K, Wu D J, Wong L L, Lu Y F et al. La-ser-induced-plasma-assisted ablation for glass microfabrication. In International Symposium on Photonics and Applications (SPIE, 2001). https://doi.org/10.1117/12.446603.
20. Huang Z Q, Hong M H, Tiaw K S, Lin Q Y. Quality glass pro-cessing by laser induced backside wet etching. J Laser Micro Nanoen 2, 194–199 (2007).
21. Zhou Y, Hong M H, Fuh J Y H, Lu L, Luk’yanchuk B S et al. Direct femtosecond laser nanopatterning of glass substrate by particle-assisted near-field enhancement. Appl Phys Lett 88, 023110 (2006).
22. Malinauskas M, ?ukauskas A, Hasegawa S, Hayasaki Y, Mizeikis V et al. Ultrafast laser processing of materials: from science to industry. Light Sci Appl 5, e16133 (2016).
23. Smith M J, Winkler M, Sher M J, Lin Y T, Mazur E et al. The effects of a thin film dopant precursor on the structure and properties of femtosecond-laser irradiated silicon. Appl Phys A 105, 795–800 (2011).
24. Mao S S, Quéré F, Guizard S, Mao X, Russo R E et al. Dynamics of femtosecond laser interactions with dielectrics. Appl Phys A 79, 1695–1709 (2004).
25. Ams M, Marshall G D, Dekker P, Dubov M, Mezentsev V K et al. Investigation of ultrafast laser--photonic material interactions: challenges for directly written glass photonics. IEEE J Sel Top Quant Electr 14, 1370–1381 (2008).
26. Sugioka K, Cheng Y. Ultrafast lasers—reliable tools for ad-vanced materials processing. Light Sci Appl 3, e149 (2014).
27. Davis K M, Miura K, Sugimoto N, Hirao K. Writing waveguides in glass with a femtosecond laser. Opt Lett 21, 1729–1731 (1996).
28. Taylor R, Hnatovsky C, Simova E. Applications of femtosecond laser induced self-organized planar nanocracks inside fused silica glass. Laser Photonics Rev 2, 26–46 (2008).
29. Beresna M, Gecevi?ius M, Kazansky P G. Ultrafast laser direct writing and nanostructuring in transparent materials. Adv Opt Photonics 6, 293–339 (2014).
30. Chan J W, Huser T, Risbud S, Krol D M. Structural changes in fused silica after exposure to focused femtosecond laser pulses. Opt Lett 26, 1726–1728 (2001).
31. Ponader C W, Schroeder J F, Streltsov A M. Origin of the refractive-index increase in laser-written waveguides in glasses. J Appl Phys 103, 063516 (2008).
32. Zoubir A, Rivero C, Grodsky R, Richardson K, Richardson M et al. Laser-induced defects in fused silica by femtosecond IR irradiation. Phys Rev B 73, 224117 (2006).
33. Sun H B, Juodkazis S, Watanabe M, Matsuo S, Misawa H et al. Generation and recombination of defects in vitreous silica in-duced by irradiation with a near-infrared femtosecond laser. J Phys Chem B 104, 3450–3455 (2000).
34. Gui L, Xu B, Chong T C. Microstructure in lithium niobate by use of focused femtosecond laser pulses. IEEE Photonic Tech Lett 16, 1337–1339 (2004).
35. Rodenas A, Kar A K. High-contrast step-index waveguides in borate nonlinear laser crystals by 3D laser writing. Opt Express 19, 17820–17833 (2011).
36. Liu J R, Zhang Z Y, Flueraru C, Liu X P, Chang S D et al. Waveguide shaping and writing in fused silica using a femto-second laser. IEEE J Sel Top Quant 10, 169–173 (2004).
37. Nejadmalayeri A H, Herman P R, Burghoff J, Will M, Nolte S et al. Inscription of optical waveguides in crystalline silicon by mid-infrared femtosecond laser pulses. Opt Lett 30, 964–966 (2005).
38. Calmano T, Siebenmorgen J, Hellmig O, Petermann K, Huber G. Nd: YAG waveguide laser with 1.3 W output power, fabricated by direct femtosecond laser writing. Appl Phys B 100, 131–135 (2010).
39. Li Q K, Lu Y M, Hua J G, Yu Y H, Wang L et al. Multilevel phase-type diffractive lens embedded in sapphire. Opt Lett 42, 3832–3835 (2017).
40. Tian Z N, Hua J G, Yu F, Yu Y H, Liu H et al. Aplanatic zone plate embedded in sapphire. IEEE Photonic Tech Lett 30, 509–512 (2018).
41. Bhardwaj V R, Simova E, Corkum P B, Rayner D M, Hnatovsky C et al. Femtosecond laser-induced refractive index modification in multicomponent glasses. J Appl Phys 97, 083102 (2005).
42. Flamini F, Magrini L, Rab A S, Spagnolo N, D'Ambrosio V et al. Thermally reconfigurable quantum photonic circuits at telecom wavelength by femtosecond laser micromachining. Light Sci Appl 4, e354 (2015).
43. Gu M, Li X P, Cao Y Y. Optical storage arrays: a perspective for future big data storage. Light Sci Appl 3, e177 (2014).
44. Wei D Z, Wang C W, Wang H J, Hu X P, Wei D et al. Experi-mental demonstration of a three-dimensional lithium niobate nonlinear photonic crystal. Nat Photonics 12, 596–600 (2018).
45. Sundaram S K, Mazur E. Inducing and probing non-thermal transitions in semiconductors using femtosecond laser pulses. Nat Mater 1, 217–224 (2002).
46. Juodkazis S, Nishimura K, Tanaka S, Misawa H, Gamaly E G et al. Laser-induced microexplosion confined in the bulk of a sapphire crystal: evidence of multimegabar pressures. Phys Rev Lett 96, 166101 (2006).
47. Gamaly E G, Juodkazis S, Nishimura K, Misawa H, Lu-ther-Davies B et al. Laser-matter interaction in the bulk of a transparent solid: Confined microexplosion and void formation. Phys Rev B 73, 214101 (2006).
48. Wuttig M, Yamada N. Phase-change materials for rewriteable data storage. Nat Mater 6, 824–832 (2007).
49. Lian C, Zhang S B, Meng S. Ab initio evidence for nonthermal characteristics in ultrafast laser melting. Phys Rev B 94, 184310 (2016).
50. Hegedüs J, Elliott S R. Microscopic origin of the fast crystallization ability of Ge–Sb–Te phase-change memory materials. Nat Mater 7, 399–405 (2008).
51. Bonse J, Baudach S, Krüger J, Kautek W, Lenzner M. Femtosecond laser ablation of silicon–modification thresholds and morphology. Appl Phys A 74, 19–25 (2014).
52. Becker M F, Buckman A B, Walser R M, Lépine T, Georges P et al. Femtosecond laser excitation of the semiconductor‐metal phase transition in VO2. Appl Phys Lett 65, 1507–1509 (1994).
53. Ma H L, Yang J Y, Dai Y, Zhang Y B, Lu B et al. Raman study of phase transformation of TiO2 rutile single crystal irradiated by infrared femtosecond laser. Appl Surf Sci 253, 7497–7500 (2007).
54. Vailionis A, Gamaly E G, Mizeikis V, Yang W G, Rode A V et al. Evidence of superdense aluminium synthesized by ultrafast microexplosion. Nat Commun 2, 445 (2011).
55. Chen N K, Han D, Li X B, Liu F, Bang J et al. Giant lattice expansion by quantum stress and universal atomic forces in semiconductors under instant ultrafast laser excitation. Phys Chem Chem Phys 19, 24735–24741 (2017).
56. Lin Y, Hong M H, Chong T C, Lim C S, Chen G X et al. Ultra-fast-laser-induced parallel phase-change nanolithography. Appl Phys Lett 89, 041108 (2006).
57. Juodkazis S, Nishimura K, Misawa H, Ebisui T, Waki R et al. Control over the crystalline state of sapphire. Adv Mater 18, 1361–1364 (2006).
58. Miotello A, Bonelli M, De Marchi G, Mattei G, Mazzoldi P et al. Formation of silver nanoclusters by excimer–laser interaction in silver-exchanged soda-lime glass. Appl Phys Lett 79, 2456 (2001).
59. Liu X Q, Chen Q D, Wang R, Wang L, Yu X L et al. Simultaneous femtosecond laser doping and surface texturing for implanting applications. Adv Mater Interfaces 2, 1500058 (2015).
60. El Hamzaoui H, Bernard R, Chahadih A, Chassagneux F, Bois L et al. Room temperature direct space-selective growth of gold nanoparticles inside a silica matrix based on a femtosecond laser irradiation. Mater Lett 64, 1279–1282 (2010).
61. Marquestaut N, Petit Y, Royon A, Mounaix P, Cardinal T et al. Three-dimensional silver nanoparticle formation using femto-second laser irradiation in phosphate glasses: analogy with photography. Adv Funct Mater 24, 5824–5832 (2014).
62. Li C, Shi X, Si J H, Chen F, Chen T et al. Photoinduced multiple microchannels inside silicon produced by a femtosecond laser. Appl Phys B 98, 377–381 (2010).
63. Liu X Q, Yu L, Ma Z C, Chen Q D. Silicon three-dimensional structures fabricated by femtosecond laser modification with dry etching. Appl Opt 56, 2157–2161 (2017).
64. Ma Y C, Wang L, Guan K M, Jiang T, Cao X W et al. Sili-con-based suspended structure fabricated by femtosecond laser direct writing and wet etching. IEEE Photonic Tech Lett 28, 1605–1608 (2016).
65. Deutsch T F, Fan J C C, Ehrlich D J, Turner G W, Chapman R L et al. Efficient GaAs solar cells formed by UV laser chemical doping. Appl Phys Lett 40, 722–724 (1982).
66. Sheehy M A, Tull B R, Friend C M, Mazur E. Chalcogen doping of silicon via intense femtosecond-laser irradiation. Mater Sci Eng B 137, 289–294 (2007).
67. Smith M J, Sher M J, Franta B, Lin Y T, Mazur E et al. Improving dopant incorporation during femtosecond-laser doping of Si with a Se thin-film dopant precursor. Appl Phys A 114, 1009–1016 (2014).
68. Paiè P, Bragheri F, Vazquez R M, Osellame R. Straightforward 3D hydrodynamic focusing in femtosecond laser fabricated microfluidic channels. Lab Chip 14, 1826–1833 (2014).
69. Wu D, Xu J, Niu L G, Wu S Z, Midorikawa K et al. In-channel integration of designable microoptical devices using flat scaf-fold-supported femtosecond-laser microfabrication for cou-pling-free optofluidic cell counting. Light Sci Appl 4, e228 (2015).
70. Marcinkevi?ius A, Juodkazis S, Watanabe M, Miwa M, Matsuo S et al. Femtosecond laser-assisted three-dimensional microfabrication in silica. Opt Lett 26, 277–279 (2001).
71. Gottmann J, Hermans M, Repiev N, Ortmann J. Selective laser-induced etching of 3D precision quartz glass components for microfluidic applications—up-scaling of complexity and speed. Micromachines 8, 110 (2017).
72. Cao X W, Chen Q D, Fan H, Zhang L, Juodkazis S et al. Liquid-assisted femtosecond laser precision-machining of silica. Nanomaterials 8, 287 (2018).
73. Kiyama S, Matsuo S, Hashimoto S, Morihira Y. Examination of etching agent and etching mechanism on femotosecond laser microfabrication of channels inside vitreous silica substrates. J Phys Chem C 113, 11560–11566 (2009).
74. Wang Z, Jiang L, Li X W, Wang A D, Yao Z L et al. High-throughput microchannel fabrication in fused silica by temporally shaped femtosecond laser Bessel-beam-assisted chemical etching. Opt Lett 43, 98–101 (2018).
75. Juodkazis S, Nishi Y, Misawa H. Femtosecond laser-assisted formation of channels in sapphire using KOH solution. Phys Status Solidi Rapid Res Lett 2, 275–277 (2008).
76. Hongo T, Sugioka K, Niino H, Cheng Y, Masuda M et al. Investigation of photoreaction mechanism of photosensitive glass by femtosecond laser. J Appl Phys 97, 063517 (2005).
77. Masuda M, Sugioka K, Cheng Y, Aoki N, Kawachi M et al. 3-D microstructuring inside photosensitive glass by femtosecond laser excitation. Appl Phys A 76, 857–860 (2003).
78. Sugioka K, Cheng Y. Integrated microchips for biological analysis fabricated by femtosecond laser direct writing. MRS Bull 36, 1020–1027 (2011).
79. Cheng Y, Sugioka K, Midorikawa K. Microfabrication of 3D hollow structures embedded in glass by femtosecond laser for Lab-on-a-chip applications. Appl Surf Sci 248, 172–176 (2005).
80. Hu Y L, Rao S L, Wu S Z, Wei P F, Qiu W X et al. All-Glass 3D optofluidic microchip with built-in tunable microlens fabricated by femtosecond laser-assisted etching. Adv Opt Mater 6, 1701299 (2018).
81. Wang C W, Yang L, Zhang C C, Rao S L, Wang Y L et al. Multilayered skyscraper microchips fabricated by hybrid "all-in-one" femtosecond laser processing. Microsyst Nanoeng 5, 17 (2019).
82. Hnatovsky C, Taylor R S, Simova E, Rajeev P P, Rayner D M et al. Fabrication of microchannels in glass using focused femto-second laser radiation and selective chemical etching. Appl Phys A 84, 47–61 (2006).
83. Bellouard Y, Said A, Dugan M, Bado P. Fabrication of high-aspect ratio, micro-fluidic channels and tunnels using femtosecond laser pulses and chemical etching. Opt Express 12, 2120–2129 (2004).
84. Wortmann D, Gottmann J, Brandt N, Horn-Solle H. Micro- and nanostructures inside sapphire by fs-laser irradiation and selective etching. Opt Express 16, 1517–1522 (2008).
85. Mazilu M, Juodkazis S, Ebisui T, Matsuo S, Misawa H. Structural characterization of shock-affected sapphire. Appl Phys A 86, 197–200 (2007).
86. Choudhury D, Rodenas A, Paterson L, Díaz F, Jaque D et al. Three-dimensional microstructuring of yttrium aluminum garnet crystals for laser active optofluidic applications. Appl Phys Lett 103, 041101 (2013).
87. Bressel L, De Ligny D, Sonneville C, Martinez V, Mizeikis V et al. Femtosecond laser induced density changes in GeO2 and SiO2 glasses: fictive temperature effect [Invited]. Opt Mater Express 1, 605–613 (2011).
88. Juodkazis S, Yamasaki K, Mizeikis V, Matsuo S, Misawa H. Formation of embedded patterns in glasses using femtosecond irradiation. Appl Phys A 79, 1549–1553 (2004).
89. Ródenas A, Gu M, Corrielli G, Paiè P, John S et al. Three-dimensional femtosecond laser nanolithography of crystals. Nat Photonics 13, 105–109 (2019).
90. Tokel O, Turnali A, Makey G, Elahi P, Colakoglu T et al. In-chip microstructures and photonic devices fabricated by nonlinear laser lithography deep inside silicon. Nat Photonics 11, 639–645 (2017).
91. Li X W, Xie Q, Jiang L, Han W N, Wang Q S et al. Controllable Si (100) micro/nanostructures by chemical-etching-assisted femtosecond laser single-pulse irradiation. Appl Phys Lett 110, 181907 (2017).
92. Shan C, Chen F, Yang Q, Li Y Y, Bian H et al. High-level integration of three-dimensional microcoils array in fused silica. Opt Lett 40, 4050–4053 (2015).
93. Bian H, Shan C, Liu K Y, Chen F, Yang Q et al. A miniaturized Rogowski current transducer with wide bandwidth and fast re-sponse. J Micromech Microeng 26, 115015 (2016).
94. Bian H, Liu H W, Chen F, Yang Q, Qu P B et al. Versatile route to gapless microlens arrays using laser-tunable wet-etched curved surfaces. Opt Express 20, 12939–12948 (2012).
95. Deng Z F, Chen F, Yang Q, Bian H, Du G Q et al. Dragon-fly-eye-inspired artificial compound eyes with sophisticated im-aging. Adv Funct Mater 26, 1995–2001 (2016).
96. Sima F, Sugioka K, Vázquez R M, Osellame R, Kelemen L et al. Three-dimensional femtosecond laser processing for lab-on-a-chip applications. Nanophotonics 7, 97 (2018).
97. Liu X Q, Chen Q D, Guan K M, Ma Z C, Yu Y H et al. Dry-etching-assisted femtosecond laser machining. Laser Photonics Rev 11, 1600115 (2017).
98. Hsu Y P, Chang S J, Su Y K, Sheu J K, Kuo C H et al. ICP etching of sapphire substrates. Opt Mater 27, 1171–1174 (2005).
99. Cao X W, Lu Y M, Fan H, Xia H, Zhang L et al. Wet-etching-assisted femtosecond laser holographic processing of a sapphire concave microlens array. Appl Opt 57, 9604–9608 (2018).
100. Liu X Q, Yang S N, Yu L, Chen Q D, Zhang Y L et al. Rapid engraving of artificial compound eyes from curved sapphire substrate. Adv Funct Mater 29, 1900037 (2019).
101. Liu X Q, Yu L, Yang S N, Chen Q D, Wang L et al. Optical nanofabrication of concave microlens arrays. Laser Photonics Rev 13, 1800272 (2019).
102. Gomez S, Jun Belen R, Kiehlbauch M, Aydil E S. Etching of high aspect ratio structures in Si using SF6/O2 plasma. J Vac Sci Technol A 22, 606–615 (2004).
103. Lallement L, Gosse C, Cardinaud C, Peignon-Fernandez M C, Rhallabi A. Etching studies of silica glasses in SF6/Ar inductively coupled plasmas: Implications for microfluidic devices fabrication. J Vac Sci Technol A 28, 277–286 (2010).
104. Liu X Q, Yu L, Chen Q D, Sun H B. Mask-free construction of three-dimensional silicon structures by dry etching assisted gray-scale femtosecond laser direct writing. Appl Phys Lett 110, 091602 (2017).
105. Lim T W, Son Y, Jeong Y J, Yang D Y, Kong H J et al. Three-dimensionally crossing manifold micro-mixer for fast mixing in a short channel length. Lab Chip 11, 100–103 (2011).
106. Gissibl T, Thiele S, Herkommer A, Giessen H. Two-photon direct laser writing of ultracompact multi-lens objectives. Nat Photonics 10, 554–560 (2016).
107. Liu X Q, Yang S N, Sun Y L, Yu L, Bai B F et al. Ultra-smooth micro-optical components of various geometries. Opt Lett 44, 2454–2457 (2019).
108. Vogelaar L, Nijdam W, Van Wolferen H A G M, De Ridder R M, Segerink F B et al. Large area photonic crystal slabs for visible light with waveguiding defect structures: fabrication with focused ion beam assisted laser interference lithography. Adv Mater 13, 1551–1554 (2001).
109. Liu C H, Hong M H, Cheung H W, Zhang F, Huang Z Q et al. Bimetallic structure fabricated by laser interference lithography for tuning surface plasmon resonance. Opt Express 16, 10701–10709 (2008).
110. Yang D, Liu L, Gong Q H, Li Y. Rapid two-photon polymerization of an arbitrary 3D microstructure with 3D focal field engineering. Macromol Rapid Commun 40, 1900041 (2019).
111. Ni J C, Wang C W, Zhang C C, Hu Y L, Yang L et al. Three-dimensional chiral microstructures fabricated by struc-tured optical vortices in isotropic material. Light Sci Appl 6, e17011 (2017).
112. He F, Xu H, Cheng Y, Ni J L, Xiong H et al. Fabrication of microfluidic channels with a circular cross section using spatiotemporally focused femtosecond laser pulses. Opt Lett 35, 1106–1108 (2010).
113. Lin J T, Xu Y X, Song J X, Zeng B, He F et al. Low-threshold whispering-gallery-mode microlasers fabricated in a Nd: glass substrate by three-dimensional femtosecond laser microm-achining. Opt Lett 38, 1458–1460 (2013).
114. Kammel R, Ackermann R, Thomas J, G?tte J, Skupin S et al. Enhancing precision in fs-laser material processing by simultaneous spatial and temporal focusing. Light Sci Appl 3, e169 (2014).
This work was supported by the National Key Research and Development Program of China and National Natural Science Foundation of China (NSFC) under Grants 2017YFB1104300, 61590930, 61825502, 61805098, and 61960206003
Get Citation: Liu X -Q, Bai B -F, Chen Q -D, Sun H -B. Etching-assisted femtosecond laser modification of hard materials. Opto-Electron Adv 2, 190021 (2019).
Next: [Opto-Electron Adv, 2019, 2(10)]Recent improvement of silicon absorption in opto-electric devices