We demonstrate the realization of sub-surface channels in sapphire prepared by ultraviolet picosecond laser irradiation and subsequent selective wet etching. By optimizing the pulse energy and the separation between individual laser pulses, an optimization of channel length can be achieved with an aspect ratio as high as 3200. Due to strong variation in channel length, further investigation was done to improve the reproducibility. By multiple irradiations the standard deviation of the channel length could be reduced to 2.2%. The achieved channel length together with the high reproducibility and the use of a commercial picosecond laser system makes the process attractive for industrial application.

© 2011 OSA

1. H. Sun, F. He, Z. Zhou, Y. Cheng, Z. Xu, K. Sugioka, and K. Midorikawa, “Fabrication of microfluidic optical waveguides on glass chips with femtosecond laser pulses,” Opt. Lett.32(11), 1536–1538 (2007). [CrossRef] [PubMed]
2. K. C. Vishnubhatla, J. Clark, G. Lanzani, R. Ramponi, R. Osellame, and T. Virgili, “Ultrafast optofluidic gain switch based on conjugated polymer in femtosecond laser fabricated microchannels,” Appl. Phys. Lett.94(4), 041123 (2009). [CrossRef]
3. C. Dongre, J. van Weerd, G. A. J. Besselink, R. M. Vazquez, R. Osellame, G. Cerullo, R. van Weeghel, H. H. van den Vlekkert, H. J. W. M. Hoekstra, and M. Pollnau, “Modulation-frequency encoded multi-color fluorescent DNA analysis in an optofluidic chip,” Lab Chip11(4), 679–683 (2011). [CrossRef] [PubMed]
4. K. C. Vishnubhatla, R. Osellame, G. Lanzani, R. Ramponi, and T. Virgili, “Organic random laser in an optofluidic chip fabricated by femtosecond laser,” Proc. SPIE7586, 75850E, 75850E-6 (2010). [CrossRef]
5. D. Wortmann, J. Gottmann, N. Brandt, and H. Horn-Solle, “Micro- and nanostructures inside sapphire by fs-laser irradiation and selective etching,” Opt. Express16(3), 1517–1522 (2008). [CrossRef] [PubMed]
6. M. Hörstmann-Jungemann, J. Gottmann, and M. Keggenhoff, “3D-Microstructuring of Sapphire using fs-Laser Irradiation and Selective Etching,” J. Laser. Micro/Nanoeng.5(2), 145–149 (2010). [CrossRef]
7. S. Matsuo, K. Tokumi, T. Tomita, and S. Hashimoto, “Three-dimensional residue-free volume removal inside sapphire by high-temperature etching after irradiation of femtosecond laser pulses,” Laser Chem.2008, 892721 (2008). [CrossRef]
8. S. Juodkazis, K. Nishimura, H. Misawa, T. Ebisui, R. Waki, S. Matsuo, and T. Okada, “Control over the Crystalline State of Sapphire,” Adv. Mater. (Deerfield Beach Fla.)18(11), 1361–1364 (2006). [CrossRef]
9. S. Juodkazis, Y. Tabuchi, T. Ebisui, S. Matsuo, and H. Misawa, “Anisotropic etching of dielectrics exposed by high intensity femtosecond pulses,” Proc. SPIE5850, 59–66 (2005). [CrossRef]
10. E. R. Dobrovinskaya, L. A. Lytvynov, and V. Pishchik, Sapphire (Springer, 2009).
11. H. Misawa, S. Juodkazis, 3D Laser Microfabrication: Principles and Applications (Wiley-VCH Verlag GmbH & Co. KGaA, 2006).
12. C. B. Schaffer, A. Brodeur, and E. Mazur, “Laser-induced breakdown and damage in bulk transparent materials induced by tightly focused femtosecond laser pulses,” Meas. Sci. Technol.12(11), 1784–1794 (2001). [CrossRef]
13. V. Mizeikis, S. Kimura, N. V. Surovtsev, V. Jarutis, A. Saito, H. Misawa, and S. Juodkazis, “Formation of amorphous sapphire by a femtosecond laser pulse induced micro-explosion,” Appl. Surf. Sci.255(24), 9745–9749 (2009). [CrossRef]
14. X. C. Wang, G. C. Lim, H. Y. Zheng, F. L. Ng, W. Liu, and S. J. Chua, “Femtosecond pulse laser ablation of sapphire in ambient air,” Appl. Surf. Sci.228(1-4), 221–226 (2004). [CrossRef]
15. D. Ashkenasi, A. Rosenfeld, H. Varel, M. Wähmer, and E. E. B. Campbell, “Laser processing of sapphire with picosecond and sub-picosecond pulses,” Appl. Surf. Sci.120(1-2), 65–80 (1997). [CrossRef]
16. M. Hörstmann-Jungemann, J. Gottmann, and D. Wortmann, “Nano- and Microstructuring of SiO2 and Sapphire with Fs-laser Induced Selective Etching,” J. Laser Micro/Nanoeng.4(2), 135–140 (2009). [CrossRef]
17. V. R. Bhardwaj, E. Simova, P. P. Rajeev, C. Hnatovsky, R. S. Taylor, D. M. Rayner, and P. B. Corkum, “Optically produced arrays of planar nanostructures inside fused silica,” Phys. Rev. Lett.96(5), 057404 (2006). [CrossRef] [PubMed]
18. C. Hnatovsky, R. S. Taylor, E. Simova, V. R. Bhardwaj, D. M. Rayner, and P. B. Corkum, “Polarization-selective etching in femtosecond laser-assisted microfluidic channel fabrication in fused silica,” Opt. Lett.30(14), 1867–1869 (2005). [CrossRef] [PubMed]

Adv. Mater. (Deerfield Beach Fla.)

• S. Juodkazis, K. Nishimura, H. Misawa, T. Ebisui, R. Waki, S. Matsuo, and T. Okada, “Control over the Crystalline State of Sapphire,” Adv. Mater. (Deerfield Beach Fla.)18(11), 1361–1364 (2006). [CrossRef]

Appl. Phys. Lett.

• K. C. Vishnubhatla, J. Clark, G. Lanzani, R. Ramponi, R. Osellame, and T. Virgili, “Ultrafast optofluidic gain switch based on conjugated polymer in femtosecond laser fabricated microchannels,” Appl. Phys. Lett.94(4), 041123 (2009). [CrossRef]

Appl. Surf. Sci.

• V. Mizeikis, S. Kimura, N. V. Surovtsev, V. Jarutis, A. Saito, H. Misawa, and S. Juodkazis, “Formation of amorphous sapphire by a femtosecond laser pulse induced micro-explosion,” Appl. Surf. Sci.255(24), 9745–9749 (2009). [CrossRef]
• X. C. Wang, G. C. Lim, H. Y. Zheng, F. L. Ng, W. Liu, and S. J. Chua, “Femtosecond pulse laser ablation of sapphire in ambient air,” Appl. Surf. Sci.228(1-4), 221–226 (2004). [CrossRef]
• D. Ashkenasi, A. Rosenfeld, H. Varel, M. Wähmer, and E. E. B. Campbell, “Laser processing of sapphire with picosecond and sub-picosecond pulses,” Appl. Surf. Sci.120(1-2), 65–80 (1997). [CrossRef]

J. Laser Micro/Nanoeng.

• M. Hörstmann-Jungemann, J. Gottmann, and D. Wortmann, “Nano- and Microstructuring of SiO2 and Sapphire with Fs-laser Induced Selective Etching,” J. Laser Micro/Nanoeng.4(2), 135–140 (2009). [CrossRef]

J. Laser. Micro/Nanoeng.

• M. Hörstmann-Jungemann, J. Gottmann, and M. Keggenhoff, “3D-Microstructuring of Sapphire using fs-Laser Irradiation and Selective Etching,” J. Laser. Micro/Nanoeng.5(2), 145–149 (2010). [CrossRef]

Lab Chip

• C. Dongre, J. van Weerd, G. A. J. Besselink, R. M. Vazquez, R. Osellame, G. Cerullo, R. van Weeghel, H. H. van den Vlekkert, H. J. W. M. Hoekstra, and M. Pollnau, “Modulation-frequency encoded multi-color fluorescent DNA analysis in an optofluidic chip,” Lab Chip11(4), 679–683 (2011). [CrossRef] [PubMed]

Laser Chem.

• S. Matsuo, K. Tokumi, T. Tomita, and S. Hashimoto, “Three-dimensional residue-free volume removal inside sapphire by high-temperature etching after irradiation of femtosecond laser pulses,” Laser Chem.2008, 892721 (2008). [CrossRef]

Meas. Sci. Technol.

• C. B. Schaffer, A. Brodeur, and E. Mazur, “Laser-induced breakdown and damage in bulk transparent materials induced by tightly focused femtosecond laser pulses,” Meas. Sci. Technol.12(11), 1784–1794 (2001). [CrossRef]

Opt. Express

• D. Wortmann, J. Gottmann, N. Brandt, and H. Horn-Solle, “Micro- and nanostructures inside sapphire by fs-laser irradiation and selective etching,” Opt. Express16(3), 1517–1522 (2008). [CrossRef] [PubMed]

Opt. Lett.

• H. Sun, F. He, Z. Zhou, Y. Cheng, Z. Xu, K. Sugioka, and K. Midorikawa, “Fabrication of microfluidic optical waveguides on glass chips with femtosecond laser pulses,” Opt. Lett.32(11), 1536–1538 (2007). [CrossRef] [PubMed]
• C. Hnatovsky, R. S. Taylor, E. Simova, V. R. Bhardwaj, D. M. Rayner, and P. B. Corkum, “Polarization-selective etching in femtosecond laser-assisted microfluidic channel fabrication in fused silica,” Opt. Lett.30(14), 1867–1869 (2005). [CrossRef] [PubMed]

Phys. Rev. Lett.

• V. R. Bhardwaj, E. Simova, P. P. Rajeev, C. Hnatovsky, R. S. Taylor, D. M. Rayner, and P. B. Corkum, “Optically produced arrays of planar nanostructures inside fused silica,” Phys. Rev. Lett.96(5), 057404 (2006). [CrossRef] [PubMed]

Proc. SPIE

• K. C. Vishnubhatla, R. Osellame, G. Lanzani, R. Ramponi, and T. Virgili, “Organic random laser in an optofluidic chip fabricated by femtosecond laser,” Proc. SPIE7586, 75850E, 75850E-6 (2010). [CrossRef]
• S. Juodkazis, Y. Tabuchi, T. Ebisui, S. Matsuo, and H. Misawa, “Anisotropic etching of dielectrics exposed by high intensity femtosecond pulses,” Proc. SPIE5850, 59–66 (2005). [CrossRef]

Other

• E. R. Dobrovinskaya, L. A. Lytvynov, and V. Pishchik, Sapphire (Springer, 2009).
• H. Misawa, S. Juodkazis, 3D Laser Microfabrication: Principles and Applications (Wiley-VCH Verlag GmbH & Co. KGaA, 2006).

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