Abstract

We report on utilizing focused ion beam milling and selective wet-etching techniques to enlarge the optical barrier in helium ion-implanted lithium niobate single crystals. We realized a high-efficiency narrow-bandwidth photonic band filter by introducing an air cavity as the optical barrier on a waveguide portion. The air cavity was created beneath the Bragg gratings (1-D photonic crystals) to strengthen the light confinement and optical response. The experimental performance of photonic crystals with and without air cavity is presented and compared with the theoretical modeling. These photonic crystal devices with high refractive-index contrast make a further step towards ultracompact optical circuit integration and applications based on single crystals.

© 2010 Optical Society of America

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References

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  1. K. K. Wong, Properties of Lithium Niobate (Institution of Electrical Engineers, 2002).
  2. E. J. Murphy, Integrated Optical Circuits and Components: Design and Applications (CRC Press, 1999).
  3. X. Lansiaux, E. Dogheche, D. Remiens, M. Guilloux-Viry, A. Perrin, and P. Ruterana, “LiNbO3 thick films grown on sapphire by using a multistep sputtering process,” J. Appl. Phys. 90, 5274–5277 (2001).
    [CrossRef]
  4. Y. Sakashita and H. J. Segawa, “Preparation and characterization of epitaxial LiNbO3 thin films by metal-organic chemical vapor deposition,” Jpn. J. Appl. Phys. 38, 5437–5441 (1999).
    [CrossRef]
  5. Y. Jong-Gul and K. Kun, “Growth of highly textured LiNbO3 thin film on Si with MgO buffer layer through the sol-gel process,” Appl. Phys. Lett. 68, 2523–2525 (1996).
    [CrossRef]
  6. J. Son, S. S. Orlov, B. Phillips, and L. Hesselink, “Pulsed laser deposition of single phase LiNbO3 thin film waveguides,” J. Electroceram. 17, 591–595 (2006).
    [CrossRef]
  7. G. Griffel, S. Ruschin, and N. I. Croitoru, “Linear electrooptic effect in sputtered polycrystalline LiNbO3 films,” Appl. Phys. Lett. 54, 1385–1387 (1989).
    [CrossRef]
  8. L. Arizmendi, “Photonic applications of lithium niobate crystals,” Phys. Status Solidi A 201, 253–283 (2004).
    [CrossRef]
  9. Z. Zhou, X. Huang, R. Vanga, and R. Li, “Tunable photonic crystals based on ferro-electric and ferro-magnetic materials by focused ion beam,” Chin. Opt. Lett. 5, 693–695 (2007).
  10. M. R. Beghoul, B. Fougere, A. Boudrioua, C. Darraud, S. Latreche, R. Kremer, P. Moretti, and J. C. Vareille, “Photonic band gap grating in He+ -implanted lithium niobate waveguides,” Opt. Quantum Electron. 39, 333–340 (2007).
    [CrossRef]
  11. M. Levy, R. M. Osgood, Jr., R. Liu, L. E. Cross, G. S. Cargill, III, A. Kumar, and H. Bakhru, “Fabrication of single-crystal lithium niobate films by crystal ion slicing,” Appl. Phys. Lett. 73, 2293–2296 (1998).
    [CrossRef]
  12. M. Levy, A. Jalali, Z. Zhou, and N. Dissanayake, “Bandgap formation and selective suppression of Bloch states in birefringent gyrotropic Bragg waveguides,” Opt. Express 16, 13421–13430 (2008).
    [CrossRef] [PubMed]
  13. X. Huang, R. Li, H. C. Yang, and M. Levy, “Multimodal and birefringence effects in magnetic photonic crystals,” J. Magn. Magn. Mater. 300, 112–116 (2006).
    [CrossRef]
  14. R. Li, X. Huang, M. Levy, and H. C. Yang, “Photonic crystal ridge waveguides on magnetic garnet films,” Mater. Res. Soc. Symp. Proc. J1.7 Vol. 834, 65–71 (2004).
    [CrossRef]
  15. X.-Y. Huang, “Dimensional effects on the magnetic domains in planar magnetophotonic crystal waveguides,” Ph. D. thesis, (Michigan Technological University, 2007).
  16. R. Vanga, “Relaxor piezoelectric film actuators, waveguides and photonic crystals: fabrication and characterization,” Ph.D. thesis (Michigan Technological University, 2008).
  17. Z. Zhou, “Metal-oxide film and photonic structures for integrated device applications,” Ph.D thesis (Michigan Technological University, 2009).
  18. Y. Kokubun, “High index contrast optical waveguides and their applications to microring filter circuit and wavelength selective switch,” IEICE Trans. Electron. 90, 1037–1045 (2007).
    [CrossRef]

2008 (1)

2007 (3)

Z. Zhou, X. Huang, R. Vanga, and R. Li, “Tunable photonic crystals based on ferro-electric and ferro-magnetic materials by focused ion beam,” Chin. Opt. Lett. 5, 693–695 (2007).

M. R. Beghoul, B. Fougere, A. Boudrioua, C. Darraud, S. Latreche, R. Kremer, P. Moretti, and J. C. Vareille, “Photonic band gap grating in He+ -implanted lithium niobate waveguides,” Opt. Quantum Electron. 39, 333–340 (2007).
[CrossRef]

Y. Kokubun, “High index contrast optical waveguides and their applications to microring filter circuit and wavelength selective switch,” IEICE Trans. Electron. 90, 1037–1045 (2007).
[CrossRef]

2006 (2)

X. Huang, R. Li, H. C. Yang, and M. Levy, “Multimodal and birefringence effects in magnetic photonic crystals,” J. Magn. Magn. Mater. 300, 112–116 (2006).
[CrossRef]

J. Son, S. S. Orlov, B. Phillips, and L. Hesselink, “Pulsed laser deposition of single phase LiNbO3 thin film waveguides,” J. Electroceram. 17, 591–595 (2006).
[CrossRef]

2004 (2)

R. Li, X. Huang, M. Levy, and H. C. Yang, “Photonic crystal ridge waveguides on magnetic garnet films,” Mater. Res. Soc. Symp. Proc. J1.7 Vol. 834, 65–71 (2004).
[CrossRef]

L. Arizmendi, “Photonic applications of lithium niobate crystals,” Phys. Status Solidi A 201, 253–283 (2004).
[CrossRef]

2001 (1)

X. Lansiaux, E. Dogheche, D. Remiens, M. Guilloux-Viry, A. Perrin, and P. Ruterana, “LiNbO3 thick films grown on sapphire by using a multistep sputtering process,” J. Appl. Phys. 90, 5274–5277 (2001).
[CrossRef]

1999 (1)

Y. Sakashita and H. J. Segawa, “Preparation and characterization of epitaxial LiNbO3 thin films by metal-organic chemical vapor deposition,” Jpn. J. Appl. Phys. 38, 5437–5441 (1999).
[CrossRef]

1998 (1)

M. Levy, R. M. Osgood, Jr., R. Liu, L. E. Cross, G. S. Cargill, III, A. Kumar, and H. Bakhru, “Fabrication of single-crystal lithium niobate films by crystal ion slicing,” Appl. Phys. Lett. 73, 2293–2296 (1998).
[CrossRef]

1996 (1)

Y. Jong-Gul and K. Kun, “Growth of highly textured LiNbO3 thin film on Si with MgO buffer layer through the sol-gel process,” Appl. Phys. Lett. 68, 2523–2525 (1996).
[CrossRef]

1989 (1)

G. Griffel, S. Ruschin, and N. I. Croitoru, “Linear electrooptic effect in sputtered polycrystalline LiNbO3 films,” Appl. Phys. Lett. 54, 1385–1387 (1989).
[CrossRef]

Arizmendi, L.

L. Arizmendi, “Photonic applications of lithium niobate crystals,” Phys. Status Solidi A 201, 253–283 (2004).
[CrossRef]

Bakhru, H.

M. Levy, R. M. Osgood, Jr., R. Liu, L. E. Cross, G. S. Cargill, III, A. Kumar, and H. Bakhru, “Fabrication of single-crystal lithium niobate films by crystal ion slicing,” Appl. Phys. Lett. 73, 2293–2296 (1998).
[CrossRef]

Beghoul, M. R.

M. R. Beghoul, B. Fougere, A. Boudrioua, C. Darraud, S. Latreche, R. Kremer, P. Moretti, and J. C. Vareille, “Photonic band gap grating in He+ -implanted lithium niobate waveguides,” Opt. Quantum Electron. 39, 333–340 (2007).
[CrossRef]

Boudrioua, A.

M. R. Beghoul, B. Fougere, A. Boudrioua, C. Darraud, S. Latreche, R. Kremer, P. Moretti, and J. C. Vareille, “Photonic band gap grating in He+ -implanted lithium niobate waveguides,” Opt. Quantum Electron. 39, 333–340 (2007).
[CrossRef]

Cargill, G. S.

M. Levy, R. M. Osgood, Jr., R. Liu, L. E. Cross, G. S. Cargill, III, A. Kumar, and H. Bakhru, “Fabrication of single-crystal lithium niobate films by crystal ion slicing,” Appl. Phys. Lett. 73, 2293–2296 (1998).
[CrossRef]

Croitoru, N. I.

G. Griffel, S. Ruschin, and N. I. Croitoru, “Linear electrooptic effect in sputtered polycrystalline LiNbO3 films,” Appl. Phys. Lett. 54, 1385–1387 (1989).
[CrossRef]

Cross, L. E.

M. Levy, R. M. Osgood, Jr., R. Liu, L. E. Cross, G. S. Cargill, III, A. Kumar, and H. Bakhru, “Fabrication of single-crystal lithium niobate films by crystal ion slicing,” Appl. Phys. Lett. 73, 2293–2296 (1998).
[CrossRef]

Darraud, C.

M. R. Beghoul, B. Fougere, A. Boudrioua, C. Darraud, S. Latreche, R. Kremer, P. Moretti, and J. C. Vareille, “Photonic band gap grating in He+ -implanted lithium niobate waveguides,” Opt. Quantum Electron. 39, 333–340 (2007).
[CrossRef]

Dissanayake, N.

Dogheche, E.

X. Lansiaux, E. Dogheche, D. Remiens, M. Guilloux-Viry, A. Perrin, and P. Ruterana, “LiNbO3 thick films grown on sapphire by using a multistep sputtering process,” J. Appl. Phys. 90, 5274–5277 (2001).
[CrossRef]

Fougere, B.

M. R. Beghoul, B. Fougere, A. Boudrioua, C. Darraud, S. Latreche, R. Kremer, P. Moretti, and J. C. Vareille, “Photonic band gap grating in He+ -implanted lithium niobate waveguides,” Opt. Quantum Electron. 39, 333–340 (2007).
[CrossRef]

Griffel, G.

G. Griffel, S. Ruschin, and N. I. Croitoru, “Linear electrooptic effect in sputtered polycrystalline LiNbO3 films,” Appl. Phys. Lett. 54, 1385–1387 (1989).
[CrossRef]

Guilloux-Viry, M.

X. Lansiaux, E. Dogheche, D. Remiens, M. Guilloux-Viry, A. Perrin, and P. Ruterana, “LiNbO3 thick films grown on sapphire by using a multistep sputtering process,” J. Appl. Phys. 90, 5274–5277 (2001).
[CrossRef]

Hesselink, L.

J. Son, S. S. Orlov, B. Phillips, and L. Hesselink, “Pulsed laser deposition of single phase LiNbO3 thin film waveguides,” J. Electroceram. 17, 591–595 (2006).
[CrossRef]

Huang, X.

Z. Zhou, X. Huang, R. Vanga, and R. Li, “Tunable photonic crystals based on ferro-electric and ferro-magnetic materials by focused ion beam,” Chin. Opt. Lett. 5, 693–695 (2007).

X. Huang, R. Li, H. C. Yang, and M. Levy, “Multimodal and birefringence effects in magnetic photonic crystals,” J. Magn. Magn. Mater. 300, 112–116 (2006).
[CrossRef]

R. Li, X. Huang, M. Levy, and H. C. Yang, “Photonic crystal ridge waveguides on magnetic garnet films,” Mater. Res. Soc. Symp. Proc. J1.7 Vol. 834, 65–71 (2004).
[CrossRef]

Huang, X.-Y.

X.-Y. Huang, “Dimensional effects on the magnetic domains in planar magnetophotonic crystal waveguides,” Ph. D. thesis, (Michigan Technological University, 2007).

Jalali, A.

Jong-Gul, Y.

Y. Jong-Gul and K. Kun, “Growth of highly textured LiNbO3 thin film on Si with MgO buffer layer through the sol-gel process,” Appl. Phys. Lett. 68, 2523–2525 (1996).
[CrossRef]

Kokubun, Y.

Y. Kokubun, “High index contrast optical waveguides and their applications to microring filter circuit and wavelength selective switch,” IEICE Trans. Electron. 90, 1037–1045 (2007).
[CrossRef]

Kremer, R.

M. R. Beghoul, B. Fougere, A. Boudrioua, C. Darraud, S. Latreche, R. Kremer, P. Moretti, and J. C. Vareille, “Photonic band gap grating in He+ -implanted lithium niobate waveguides,” Opt. Quantum Electron. 39, 333–340 (2007).
[CrossRef]

Kumar, A.

M. Levy, R. M. Osgood, Jr., R. Liu, L. E. Cross, G. S. Cargill, III, A. Kumar, and H. Bakhru, “Fabrication of single-crystal lithium niobate films by crystal ion slicing,” Appl. Phys. Lett. 73, 2293–2296 (1998).
[CrossRef]

Kun, K.

Y. Jong-Gul and K. Kun, “Growth of highly textured LiNbO3 thin film on Si with MgO buffer layer through the sol-gel process,” Appl. Phys. Lett. 68, 2523–2525 (1996).
[CrossRef]

Lansiaux, X.

X. Lansiaux, E. Dogheche, D. Remiens, M. Guilloux-Viry, A. Perrin, and P. Ruterana, “LiNbO3 thick films grown on sapphire by using a multistep sputtering process,” J. Appl. Phys. 90, 5274–5277 (2001).
[CrossRef]

Latreche, S.

M. R. Beghoul, B. Fougere, A. Boudrioua, C. Darraud, S. Latreche, R. Kremer, P. Moretti, and J. C. Vareille, “Photonic band gap grating in He+ -implanted lithium niobate waveguides,” Opt. Quantum Electron. 39, 333–340 (2007).
[CrossRef]

Levy, M.

M. Levy, A. Jalali, Z. Zhou, and N. Dissanayake, “Bandgap formation and selective suppression of Bloch states in birefringent gyrotropic Bragg waveguides,” Opt. Express 16, 13421–13430 (2008).
[CrossRef] [PubMed]

X. Huang, R. Li, H. C. Yang, and M. Levy, “Multimodal and birefringence effects in magnetic photonic crystals,” J. Magn. Magn. Mater. 300, 112–116 (2006).
[CrossRef]

R. Li, X. Huang, M. Levy, and H. C. Yang, “Photonic crystal ridge waveguides on magnetic garnet films,” Mater. Res. Soc. Symp. Proc. J1.7 Vol. 834, 65–71 (2004).
[CrossRef]

M. Levy, R. M. Osgood, Jr., R. Liu, L. E. Cross, G. S. Cargill, III, A. Kumar, and H. Bakhru, “Fabrication of single-crystal lithium niobate films by crystal ion slicing,” Appl. Phys. Lett. 73, 2293–2296 (1998).
[CrossRef]

Li, R.

Z. Zhou, X. Huang, R. Vanga, and R. Li, “Tunable photonic crystals based on ferro-electric and ferro-magnetic materials by focused ion beam,” Chin. Opt. Lett. 5, 693–695 (2007).

X. Huang, R. Li, H. C. Yang, and M. Levy, “Multimodal and birefringence effects in magnetic photonic crystals,” J. Magn. Magn. Mater. 300, 112–116 (2006).
[CrossRef]

R. Li, X. Huang, M. Levy, and H. C. Yang, “Photonic crystal ridge waveguides on magnetic garnet films,” Mater. Res. Soc. Symp. Proc. J1.7 Vol. 834, 65–71 (2004).
[CrossRef]

Liu, R.

M. Levy, R. M. Osgood, Jr., R. Liu, L. E. Cross, G. S. Cargill, III, A. Kumar, and H. Bakhru, “Fabrication of single-crystal lithium niobate films by crystal ion slicing,” Appl. Phys. Lett. 73, 2293–2296 (1998).
[CrossRef]

Moretti, P.

M. R. Beghoul, B. Fougere, A. Boudrioua, C. Darraud, S. Latreche, R. Kremer, P. Moretti, and J. C. Vareille, “Photonic band gap grating in He+ -implanted lithium niobate waveguides,” Opt. Quantum Electron. 39, 333–340 (2007).
[CrossRef]

Murphy, E. J.

E. J. Murphy, Integrated Optical Circuits and Components: Design and Applications (CRC Press, 1999).

Orlov, S. S.

J. Son, S. S. Orlov, B. Phillips, and L. Hesselink, “Pulsed laser deposition of single phase LiNbO3 thin film waveguides,” J. Electroceram. 17, 591–595 (2006).
[CrossRef]

Osgood, R. M.

M. Levy, R. M. Osgood, Jr., R. Liu, L. E. Cross, G. S. Cargill, III, A. Kumar, and H. Bakhru, “Fabrication of single-crystal lithium niobate films by crystal ion slicing,” Appl. Phys. Lett. 73, 2293–2296 (1998).
[CrossRef]

Perrin, A.

X. Lansiaux, E. Dogheche, D. Remiens, M. Guilloux-Viry, A. Perrin, and P. Ruterana, “LiNbO3 thick films grown on sapphire by using a multistep sputtering process,” J. Appl. Phys. 90, 5274–5277 (2001).
[CrossRef]

Phillips, B.

J. Son, S. S. Orlov, B. Phillips, and L. Hesselink, “Pulsed laser deposition of single phase LiNbO3 thin film waveguides,” J. Electroceram. 17, 591–595 (2006).
[CrossRef]

Remiens, D.

X. Lansiaux, E. Dogheche, D. Remiens, M. Guilloux-Viry, A. Perrin, and P. Ruterana, “LiNbO3 thick films grown on sapphire by using a multistep sputtering process,” J. Appl. Phys. 90, 5274–5277 (2001).
[CrossRef]

Ruschin, S.

G. Griffel, S. Ruschin, and N. I. Croitoru, “Linear electrooptic effect in sputtered polycrystalline LiNbO3 films,” Appl. Phys. Lett. 54, 1385–1387 (1989).
[CrossRef]

Ruterana, P.

X. Lansiaux, E. Dogheche, D. Remiens, M. Guilloux-Viry, A. Perrin, and P. Ruterana, “LiNbO3 thick films grown on sapphire by using a multistep sputtering process,” J. Appl. Phys. 90, 5274–5277 (2001).
[CrossRef]

Sakashita, Y.

Y. Sakashita and H. J. Segawa, “Preparation and characterization of epitaxial LiNbO3 thin films by metal-organic chemical vapor deposition,” Jpn. J. Appl. Phys. 38, 5437–5441 (1999).
[CrossRef]

Segawa, H. J.

Y. Sakashita and H. J. Segawa, “Preparation and characterization of epitaxial LiNbO3 thin films by metal-organic chemical vapor deposition,” Jpn. J. Appl. Phys. 38, 5437–5441 (1999).
[CrossRef]

Son, J.

J. Son, S. S. Orlov, B. Phillips, and L. Hesselink, “Pulsed laser deposition of single phase LiNbO3 thin film waveguides,” J. Electroceram. 17, 591–595 (2006).
[CrossRef]

Vanga, R.

Z. Zhou, X. Huang, R. Vanga, and R. Li, “Tunable photonic crystals based on ferro-electric and ferro-magnetic materials by focused ion beam,” Chin. Opt. Lett. 5, 693–695 (2007).

R. Vanga, “Relaxor piezoelectric film actuators, waveguides and photonic crystals: fabrication and characterization,” Ph.D. thesis (Michigan Technological University, 2008).

Vareille, J. C.

M. R. Beghoul, B. Fougere, A. Boudrioua, C. Darraud, S. Latreche, R. Kremer, P. Moretti, and J. C. Vareille, “Photonic band gap grating in He+ -implanted lithium niobate waveguides,” Opt. Quantum Electron. 39, 333–340 (2007).
[CrossRef]

Wong, K. K.

K. K. Wong, Properties of Lithium Niobate (Institution of Electrical Engineers, 2002).

Yang, H. C.

X. Huang, R. Li, H. C. Yang, and M. Levy, “Multimodal and birefringence effects in magnetic photonic crystals,” J. Magn. Magn. Mater. 300, 112–116 (2006).
[CrossRef]

R. Li, X. Huang, M. Levy, and H. C. Yang, “Photonic crystal ridge waveguides on magnetic garnet films,” Mater. Res. Soc. Symp. Proc. J1.7 Vol. 834, 65–71 (2004).
[CrossRef]

Zhou, Z.

Appl. Phys. Lett. (3)

Y. Jong-Gul and K. Kun, “Growth of highly textured LiNbO3 thin film on Si with MgO buffer layer through the sol-gel process,” Appl. Phys. Lett. 68, 2523–2525 (1996).
[CrossRef]

G. Griffel, S. Ruschin, and N. I. Croitoru, “Linear electrooptic effect in sputtered polycrystalline LiNbO3 films,” Appl. Phys. Lett. 54, 1385–1387 (1989).
[CrossRef]

M. Levy, R. M. Osgood, Jr., R. Liu, L. E. Cross, G. S. Cargill, III, A. Kumar, and H. Bakhru, “Fabrication of single-crystal lithium niobate films by crystal ion slicing,” Appl. Phys. Lett. 73, 2293–2296 (1998).
[CrossRef]

Chin. Opt. Lett. (1)

IEICE Trans. Electron. (1)

Y. Kokubun, “High index contrast optical waveguides and their applications to microring filter circuit and wavelength selective switch,” IEICE Trans. Electron. 90, 1037–1045 (2007).
[CrossRef]

J. Appl. Phys. (1)

X. Lansiaux, E. Dogheche, D. Remiens, M. Guilloux-Viry, A. Perrin, and P. Ruterana, “LiNbO3 thick films grown on sapphire by using a multistep sputtering process,” J. Appl. Phys. 90, 5274–5277 (2001).
[CrossRef]

J. Electroceram. (1)

J. Son, S. S. Orlov, B. Phillips, and L. Hesselink, “Pulsed laser deposition of single phase LiNbO3 thin film waveguides,” J. Electroceram. 17, 591–595 (2006).
[CrossRef]

J. Magn. Magn. Mater. (1)

X. Huang, R. Li, H. C. Yang, and M. Levy, “Multimodal and birefringence effects in magnetic photonic crystals,” J. Magn. Magn. Mater. 300, 112–116 (2006).
[CrossRef]

Jpn. J. Appl. Phys. (1)

Y. Sakashita and H. J. Segawa, “Preparation and characterization of epitaxial LiNbO3 thin films by metal-organic chemical vapor deposition,” Jpn. J. Appl. Phys. 38, 5437–5441 (1999).
[CrossRef]

Mater. Res. Soc. Symp. Proc. (1)

R. Li, X. Huang, M. Levy, and H. C. Yang, “Photonic crystal ridge waveguides on magnetic garnet films,” Mater. Res. Soc. Symp. Proc. J1.7 Vol. 834, 65–71 (2004).
[CrossRef]

Opt. Express (1)

Opt. Quantum Electron. (1)

M. R. Beghoul, B. Fougere, A. Boudrioua, C. Darraud, S. Latreche, R. Kremer, P. Moretti, and J. C. Vareille, “Photonic band gap grating in He+ -implanted lithium niobate waveguides,” Opt. Quantum Electron. 39, 333–340 (2007).
[CrossRef]

Phys. Status Solidi A (1)

L. Arizmendi, “Photonic applications of lithium niobate crystals,” Phys. Status Solidi A 201, 253–283 (2004).
[CrossRef]

Other (5)

K. K. Wong, Properties of Lithium Niobate (Institution of Electrical Engineers, 2002).

E. J. Murphy, Integrated Optical Circuits and Components: Design and Applications (CRC Press, 1999).

X.-Y. Huang, “Dimensional effects on the magnetic domains in planar magnetophotonic crystal waveguides,” Ph. D. thesis, (Michigan Technological University, 2007).

R. Vanga, “Relaxor piezoelectric film actuators, waveguides and photonic crystals: fabrication and characterization,” Ph.D. thesis (Michigan Technological University, 2008).

Z. Zhou, “Metal-oxide film and photonic structures for integrated device applications,” Ph.D thesis (Michigan Technological University, 2009).

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Figures (9)

Fig. 1
Fig. 1

Schematic illustration of refractive index contrast enhancement.

Fig. 2
Fig. 2

Schematic cross-sectional illustration of the fabrication process to introduce an air cavity beneath the waveguides.

Fig. 3
Fig. 3

(a) SEM image of the top view of the sample. (b) SEM image of the window opened by FIB to generate air cavity (black line). (c) SEM image of the Bragg gratings. (d) Cross-sectional SEM image of the ridge waveguide with air cavity (black line).

Fig. 4
Fig. 4

Optical microscopy image of the Bragg gratings showing optically contrasted air cavities beneath waveguides.

Fig. 5
Fig. 5

Schematic illustration of the optical measurement setup.

Fig. 6
Fig. 6

Experimental measurement of the transmission spectrum of three samples without air cavity. The grating periods of sample A, B, and C are 354.5 nm , 359 nm , and 363 nm , correspondingly.

Fig. 7
Fig. 7

Experimental measurement of the transmission spectrum of a sample ( period = 352 nm ) with air cavity.

Fig. 8
Fig. 8

The calculated penetration depth of light waves in the substrate according to index difference between the film and the substrate.

Fig. 9
Fig. 9

The modeling results of transmission spectrum of three conditions: the index difference between the film and the substrate is 0.02, 0.05, 0.30, and 1.10.

Metrics