Abstract

Very smooth relief microstructures were fabricated in X-cut Lithium Niobate by using an improved ion implantation-assisted wet etching technique. The substrates were implanted with 5 MeV Cu ions at a fluence of 1 × 10<sup>15</sup> cm<sup>-2</sup> through a masking layer. Three kinds of layers were patterned and tested: Au, positive photoresist and SU-8 negative photoresist. The damaged regions were then etched with a HF solution at a rate of 100 nm/s. The process can be repeated to obtain higher aspect ratios. The relief structures fabricated with this technology are presented and discussed. In order to explore a possible application of our technique optical waveguides were created in the best quality structures by means of a multi-step carbon ion implantation process with ten different energies followed by an annealing at 280°C for 30 minutes. In this way a step-like enhanced extraordinary refractive index profile was obtained inside the ridges extending from surface to a depth of 2.75 <i>μm</i>. Optical characterization @ 660 nm of the waveguides yielded a propagation loss of 0.23 ± 0.09 dB/cm. The very good results of the best structures make them very promising for integrated optics and acousto/opto-fluidics.

© 2013 IEEE

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  1. K. K. Wong, Properties of Lithium Niobate (IEE INSPEC, 2002).
  2. J. Friend, L. Y. Yeo, "Microscale acoustofluidics: Microfluidics driven via acoustics and ultrasonics," Rev. Mod. Phys. 83, 647-704 (2011).
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  7. N. Courjal, B. Guichardaz, G. Ulliac, J. Y. Rauch, B. Sadani, H. H. Lu, M. P. Bernal, "High aspect ratio lithium niobate ridge waveguides fabricated by optical grade dicing," J. Phys. D: Appl. Phys. 44, 305101-305107 (2011).
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  13. D. M. Gill, D. Jacobson, C. A. White, C. D. W. Jones, Y. Shi, W. J. Minford, A. Harris, "Ridged LiNbO3 modulators fabricated by a novel oxygen-ion implant/wet-etch technique," J. Lightw. Technol. 22, 887-894 (2004).
  14. M. Bianconi, G. G. Bentini, M. Chiarini, P. De Nicola, G. B. Montanari, A. Nubile, S. Sugliani, "Defect engineering and micromachining of lithium niobate by ion implantation," Nucl. Instrum. Meth. B 267, 2839-2845 (2009).
  15. M. Bianconi, G. G. Bentini, M. Chiarini, P. De Nicola, G. B. Montanari, A. Menin, A. Nubile, S. Sugliani, "Simulation of damage induced by ion implantation in lithium niobate," Nucl. Instrum. Meth. B 268, 3452-3457 (2010).
  16. G. B. Montanari, P. De Nicola, S. Sugliani, A. Menin, A. Parini, A. Nubile, G. Bellanca, M. Chiarini, M. Bianconi, G. G. Bentini, "Step-index optical waveguide produced by multi-step ion implantation in LiNbO3," Opt. Exp. 20, 4444-4453 (2012).
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2012 (1)

G. B. Montanari, P. De Nicola, S. Sugliani, A. Menin, A. Parini, A. Nubile, G. Bellanca, M. Chiarini, M. Bianconi, G. G. Bentini, "Step-index optical waveguide produced by multi-step ion implantation in LiNbO3," Opt. Exp. 20, 4444-4453 (2012).

2011 (3)

J. Friend, L. Y. Yeo, "Microscale acoustofluidics: Microfluidics driven via acoustics and ultrasonics," Rev. Mod. Phys. 83, 647-704 (2011).

G. Ulliac, B. Guichardaz, J.-Y. Rauch, S. Queste, S. Benchabane, N. Courjal, "Ultra-smooth LiNbO3 micro and nano structures for photonic applications," Microelectron. Eng. 88, 2417-2419 (2011).

N. Courjal, B. Guichardaz, G. Ulliac, J. Y. Rauch, B. Sadani, H. H. Lu, M. P. Bernal, "High aspect ratio lithium niobate ridge waveguides fabricated by optical grade dicing," J. Phys. D: Appl. Phys. 44, 305101-305107 (2011).

2010 (4)

C. L. Sones, P. Ganguly, Y. J. Ying, Soergel, R. W. Eason, S. Mailis, "Poling-inhibited ridge waveguides in lithium niobate crystals," Appl. Phys. Lett. 97, 151112-151114 (2010).

H. Hu, R. Ricken, W. Sohler, "Low-loss ridge waveguides on lithium niobate fabricated by local diffusion doping with titanium," Appl. Phys. B 98, 677-679 (2010).

M. Bianconi, G. G. Bentini, M. Chiarini, P. De Nicola, G. B. Montanari, A. Menin, A. Nubile, S. Sugliani, "Simulation of damage induced by ion implantation in lithium niobate," Nucl. Instrum. Meth. B 268, 3452-3457 (2010).

G. Si, E. J. Teo, A. A. Bettiol, J. Teng, A. J. Danner, "Suspended slab and photonic crystal waveguides in lithium niobate," IEEE J. Vac. Sci. Technol. B 28, 316-320 (2010).

2009 (2)

H. Hu, R. Ricken, W. Sohler, "Lithium niobate photonic wires," Opt. Exp. 17, 24261-24268 (2009).

M. Bianconi, G. G. Bentini, M. Chiarini, P. De Nicola, G. B. Montanari, A. Nubile, S. Sugliani, "Defect engineering and micromachining of lithium niobate by ion implantation," Nucl. Instrum. Meth. B 267, 2839-2845 (2009).

2008 (1)

Z. Ren, P. J. Heard, J. M. Marshall, P. A. Thomas, S. Yu, "Etching characteristics of LiNbO3 in reactive ion etching and inductively coupled plasma," J. Appl. Phys. 103, 034109-034116 (2008).

2007 (1)

D. W. Ward, E. R. Statz, K. A. Nelson, "Fabrication of polaritonic structures in LiNbO3 and LiTaO3 using femtosecond laser machining," Appl. Phys. A 86, 49-54 (2007).

2006 (1)

D. Psaltis, S. R. Quake, C. Yang, "Developing optofluidic technology through the fusion of microfluidics and optics," Nature 442, 381-386 (2006).

2004 (2)

T. J. Wang, C. F. Huang, W. S. Wang, P. K. Wei, "A novel wet-etching method using electric field-assisted proton exchange in LiNbO3," J. Lightw. Technol. 22, 1764-1771 (2004).

D. M. Gill, D. Jacobson, C. A. White, C. D. W. Jones, Y. Shi, W. J. Minford, A. Harris, "Ridged LiNbO3 modulators fabricated by a novel oxygen-ion implant/wet-etch technique," J. Lightw. Technol. 22, 887-894 (2004).

Appl. Phys. A (1)

D. W. Ward, E. R. Statz, K. A. Nelson, "Fabrication of polaritonic structures in LiNbO3 and LiTaO3 using femtosecond laser machining," Appl. Phys. A 86, 49-54 (2007).

Appl. Phys. B (1)

H. Hu, R. Ricken, W. Sohler, "Low-loss ridge waveguides on lithium niobate fabricated by local diffusion doping with titanium," Appl. Phys. B 98, 677-679 (2010).

Appl. Phys. Lett. (1)

C. L. Sones, P. Ganguly, Y. J. Ying, Soergel, R. W. Eason, S. Mailis, "Poling-inhibited ridge waveguides in lithium niobate crystals," Appl. Phys. Lett. 97, 151112-151114 (2010).

IEEE J. Vac. Sci. Technol. B (1)

G. Si, E. J. Teo, A. A. Bettiol, J. Teng, A. J. Danner, "Suspended slab and photonic crystal waveguides in lithium niobate," IEEE J. Vac. Sci. Technol. B 28, 316-320 (2010).

J. Appl. Phys. (1)

Z. Ren, P. J. Heard, J. M. Marshall, P. A. Thomas, S. Yu, "Etching characteristics of LiNbO3 in reactive ion etching and inductively coupled plasma," J. Appl. Phys. 103, 034109-034116 (2008).

J. Lightw. Technol. (2)

D. M. Gill, D. Jacobson, C. A. White, C. D. W. Jones, Y. Shi, W. J. Minford, A. Harris, "Ridged LiNbO3 modulators fabricated by a novel oxygen-ion implant/wet-etch technique," J. Lightw. Technol. 22, 887-894 (2004).

T. J. Wang, C. F. Huang, W. S. Wang, P. K. Wei, "A novel wet-etching method using electric field-assisted proton exchange in LiNbO3," J. Lightw. Technol. 22, 1764-1771 (2004).

J. Phys. D: Appl. Phys. (1)

N. Courjal, B. Guichardaz, G. Ulliac, J. Y. Rauch, B. Sadani, H. H. Lu, M. P. Bernal, "High aspect ratio lithium niobate ridge waveguides fabricated by optical grade dicing," J. Phys. D: Appl. Phys. 44, 305101-305107 (2011).

Microelectron. Eng. (1)

G. Ulliac, B. Guichardaz, J.-Y. Rauch, S. Queste, S. Benchabane, N. Courjal, "Ultra-smooth LiNbO3 micro and nano structures for photonic applications," Microelectron. Eng. 88, 2417-2419 (2011).

Nature (1)

D. Psaltis, S. R. Quake, C. Yang, "Developing optofluidic technology through the fusion of microfluidics and optics," Nature 442, 381-386 (2006).

Nucl. Instrum. Meth. B (2)

M. Bianconi, G. G. Bentini, M. Chiarini, P. De Nicola, G. B. Montanari, A. Nubile, S. Sugliani, "Defect engineering and micromachining of lithium niobate by ion implantation," Nucl. Instrum. Meth. B 267, 2839-2845 (2009).

M. Bianconi, G. G. Bentini, M. Chiarini, P. De Nicola, G. B. Montanari, A. Menin, A. Nubile, S. Sugliani, "Simulation of damage induced by ion implantation in lithium niobate," Nucl. Instrum. Meth. B 268, 3452-3457 (2010).

Opt. Exp. (2)

G. B. Montanari, P. De Nicola, S. Sugliani, A. Menin, A. Parini, A. Nubile, G. Bellanca, M. Chiarini, M. Bianconi, G. G. Bentini, "Step-index optical waveguide produced by multi-step ion implantation in LiNbO3," Opt. Exp. 20, 4444-4453 (2012).

H. Hu, R. Ricken, W. Sohler, "Lithium niobate photonic wires," Opt. Exp. 17, 24261-24268 (2009).

Rev. Mod. Phys. (1)

J. Friend, L. Y. Yeo, "Microscale acoustofluidics: Microfluidics driven via acoustics and ultrasonics," Rev. Mod. Phys. 83, 647-704 (2011).

Other (4)

K. K. Wong, Properties of Lithium Niobate (IEE INSPEC, 2002).

J. F. Ziegler, J. P. Biersack, M. D. Ziegler, (1985)The Stopping and Ranges of Ions in Solids. http://www.srim.org.

MicroChem Corp.SU-8 Negative Epoxy Series Resists, Data Sheets, http://www.microchem.com/Prod-SU8_KMPR.htm.

G. B. Montanari, Optical Microring Resonators Based on Ion-Implanted LiNbO3 Ridge Waveguides Ph.D. dissertation DEIS Univ. BolognaBolognaItaly (2010).

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