Abstract

Mechanisms of the femtosecond-laser-induced refractive-index change (Δn) were investigated for fused silica and a borosilicate glass. Experiments were based on two exposure situations: (a) high repetition rate and low pulse energy and (b) low repetition rate and high pulse energy. The calculated temperature rise based on model (b) was above 1000 °C, whereas for situation (a) it was negligible. The results do not support a thermal origin of the induced Δn; rather, heat may limit the magnitude of the change. Correlation between color-center formation and Δn in both glasses suggests that defects contribute substantially to the index increase. However, annealing studies have shown that the induced Δn persisted beyond the disappearance of the color centers. Analysis of the induced stress showed that densification plays a small role in this change.

© 2002 Optical Society of America

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References

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  1. K. Hirao and K. Miura, “Writing waveguides and gratings in silica and related materials by a femtosecond laser,” J. Non-Cryst. Solids 239, 91–95 (1998).
    [CrossRef]
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    [CrossRef]
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    [CrossRef]
  4. L. Sudrie, M. Franco, B. Prade, and A. Mysyrowicz, “Writing of permanent birefringent microlayers in bulk fused silica with femtosecond laser pulses,” Opt. Commun. 171, 279–284 (1999).
    [CrossRef]
  5. P. Oberson, B. Gisin, B. Huttner, and N. Gisin, “Refracted near-field measurements of refractive index and geometry of silica-on-silicon integrated optical waveguides,” Appl. Opt. 37, 7268–7272 (1998).
    [CrossRef]
  6. K. Minoshima, A. M. Kowalevicz, I. Hartl, E. P. Ippen, and J. G. Fujimoto, “Photonic device fabrication in glass by use of nonlinear materials processing with a femtosecond laser oscillator,” Opt. Lett. 26, 1516–1518 (2001).
    [CrossRef]
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    [CrossRef]
  8. M. Lenzner, J. Krugler, S. Sartania, Z. Cheng, C. Spielmann, W. Kautek, and F. Krausz, “Femtosecond optical breakdown in dielectrics,” Phys. Rev. Lett. 80, 4076–4079 (1998).
    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]

2001 (4)

2000 (1)

A. Kaiser, B. Rethfeld, M. Vicanek, and G. Simon, “Microscopic processes in dielectrics under irradiation by subpicosecond laser pulses,” Phys. Rev. B 61, 11, 437–11, 450 (2000).
[CrossRef]

1999 (2)

N. F. Borrelli, C. M. Smith, and D. C. Allan, “Excimer-laser-induced densification in binary silicate glasses,” Opt. Lett. 24, 1401–1403 (1999).
[CrossRef]

L. Sudrie, M. Franco, B. Prade, and A. Mysyrowicz, “Writing of permanent birefringent microlayers in bulk fused silica with femtosecond laser pulses,” Opt. Commun. 171, 279–284 (1999).
[CrossRef]

1998 (3)

M. Lenzner, J. Krugler, S. Sartania, Z. Cheng, C. Spielmann, W. Kautek, and F. Krausz, “Femtosecond optical breakdown in dielectrics,” Phys. Rev. Lett. 80, 4076–4079 (1998).
[CrossRef]

P. Oberson, B. Gisin, B. Huttner, and N. Gisin, “Refracted near-field measurements of refractive index and geometry of silica-on-silicon integrated optical waveguides,” Appl. Opt. 37, 7268–7272 (1998).
[CrossRef]

K. Hirao and K. Miura, “Writing waveguides and gratings in silica and related materials by a femtosecond laser,” J. Non-Cryst. Solids 239, 91–95 (1998).
[CrossRef]

1997 (2)

K. O. Hill and G. Meltz, “Fiber Bragg grating technology fundamentals and overview,” J. Lightwave Technol. 15, 1263–1267 (1997).
[CrossRef]

N. F. Borrelli, C. Smith, D. C. Allan, and T. P. Seward III, “Densification of fused silica under 193-nm excitation,” J. Opt. Soc. Am. B 14, 1606–1615 (1997).
[CrossRef]

1994 (1)

D. Du, X. Liu, G. Korn, J. Squier, and G. Mourou, “Laser-induced breakdown by impact ionization on silica with pulse widths from 7-ns to 150-fs,” Appl. Phys. Lett. 64, 3071–3073 (1994).
[CrossRef]

1965 (1)

L. V. Keldysh, “Ionization in the field of a strong em wave,” Sov. Phys. JETP 20, 1307–1314 (1965).

Allan, D. C.

Borrelli, N.

Borrelli, N. F.

Brodeur, A.

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, 1784–1794 (2001).
[CrossRef]

Chan, J.

Cheng, Z.

M. Lenzner, J. Krugler, S. Sartania, Z. Cheng, C. Spielmann, W. Kautek, and F. Krausz, “Femtosecond optical breakdown in dielectrics,” Phys. Rev. Lett. 80, 4076–4079 (1998).
[CrossRef]

Du, D.

D. Du, X. Liu, G. Korn, J. Squier, and G. Mourou, “Laser-induced breakdown by impact ionization on silica with pulse widths from 7-ns to 150-fs,” Appl. Phys. Lett. 64, 3071–3073 (1994).
[CrossRef]

Franco, M.

L. Sudrie, M. Franco, B. Prade, and A. Mysyrowicz, “Writing of permanent birefringent microlayers in bulk fused silica with femtosecond laser pulses,” Opt. Commun. 171, 279–284 (1999).
[CrossRef]

Fujimoto, J. G.

Gisin, B.

Gisin, N.

Hartl, I.

Hill, K. O.

K. O. Hill and G. Meltz, “Fiber Bragg grating technology fundamentals and overview,” J. Lightwave Technol. 15, 1263–1267 (1997).
[CrossRef]

Hirao, K.

K. Hirao and K. Miura, “Writing waveguides and gratings in silica and related materials by a femtosecond laser,” J. Non-Cryst. Solids 239, 91–95 (1998).
[CrossRef]

Huser, T.

Huttner, B.

Ippen, E. P.

Kaiser, A.

A. Kaiser, B. Rethfeld, M. Vicanek, and G. Simon, “Microscopic processes in dielectrics under irradiation by subpicosecond laser pulses,” Phys. Rev. B 61, 11, 437–11, 450 (2000).
[CrossRef]

Kautek, W.

M. Lenzner, J. Krugler, S. Sartania, Z. Cheng, C. Spielmann, W. Kautek, and F. Krausz, “Femtosecond optical breakdown in dielectrics,” Phys. Rev. Lett. 80, 4076–4079 (1998).
[CrossRef]

Keldysh, L. V.

L. V. Keldysh, “Ionization in the field of a strong em wave,” Sov. Phys. JETP 20, 1307–1314 (1965).

Korn, G.

D. Du, X. Liu, G. Korn, J. Squier, and G. Mourou, “Laser-induced breakdown by impact ionization on silica with pulse widths from 7-ns to 150-fs,” Appl. Phys. Lett. 64, 3071–3073 (1994).
[CrossRef]

Kowalevicz, A. M.

Krausz, F.

M. Lenzner, J. Krugler, S. Sartania, Z. Cheng, C. Spielmann, W. Kautek, and F. Krausz, “Femtosecond optical breakdown in dielectrics,” Phys. Rev. Lett. 80, 4076–4079 (1998).
[CrossRef]

Krol, D.

Krugler, J.

M. Lenzner, J. Krugler, S. Sartania, Z. Cheng, C. Spielmann, W. Kautek, and F. Krausz, “Femtosecond optical breakdown in dielectrics,” Phys. Rev. Lett. 80, 4076–4079 (1998).
[CrossRef]

Lenzner, M.

M. Lenzner, J. Krugler, S. Sartania, Z. Cheng, C. Spielmann, W. Kautek, and F. Krausz, “Femtosecond optical breakdown in dielectrics,” Phys. Rev. Lett. 80, 4076–4079 (1998).
[CrossRef]

Liu, X.

D. Du, X. Liu, G. Korn, J. Squier, and G. Mourou, “Laser-induced breakdown by impact ionization on silica with pulse widths from 7-ns to 150-fs,” Appl. Phys. Lett. 64, 3071–3073 (1994).
[CrossRef]

Mazur, E.

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, 1784–1794 (2001).
[CrossRef]

Meltz, G.

K. O. Hill and G. Meltz, “Fiber Bragg grating technology fundamentals and overview,” J. Lightwave Technol. 15, 1263–1267 (1997).
[CrossRef]

Minoshima, K.

Miura, K.

K. Hirao and K. Miura, “Writing waveguides and gratings in silica and related materials by a femtosecond laser,” J. Non-Cryst. Solids 239, 91–95 (1998).
[CrossRef]

Mourou, G.

D. Du, X. Liu, G. Korn, J. Squier, and G. Mourou, “Laser-induced breakdown by impact ionization on silica with pulse widths from 7-ns to 150-fs,” Appl. Phys. Lett. 64, 3071–3073 (1994).
[CrossRef]

Mysyrowicz, A.

L. Sudrie, M. Franco, B. Prade, and A. Mysyrowicz, “Writing of permanent birefringent microlayers in bulk fused silica with femtosecond laser pulses,” Opt. Commun. 171, 279–284 (1999).
[CrossRef]

Oberson, P.

Prade, B.

L. Sudrie, M. Franco, B. Prade, and A. Mysyrowicz, “Writing of permanent birefringent microlayers in bulk fused silica with femtosecond laser pulses,” Opt. Commun. 171, 279–284 (1999).
[CrossRef]

Rethfeld, B.

A. Kaiser, B. Rethfeld, M. Vicanek, and G. Simon, “Microscopic processes in dielectrics under irradiation by subpicosecond laser pulses,” Phys. Rev. B 61, 11, 437–11, 450 (2000).
[CrossRef]

Risbud, S.

Sartania, S.

M. Lenzner, J. Krugler, S. Sartania, Z. Cheng, C. Spielmann, W. Kautek, and F. Krausz, “Femtosecond optical breakdown in dielectrics,” Phys. Rev. Lett. 80, 4076–4079 (1998).
[CrossRef]

Schaffer, C. B.

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, 1784–1794 (2001).
[CrossRef]

Seward III, T. P.

Simon, G.

A. Kaiser, B. Rethfeld, M. Vicanek, and G. Simon, “Microscopic processes in dielectrics under irradiation by subpicosecond laser pulses,” Phys. Rev. B 61, 11, 437–11, 450 (2000).
[CrossRef]

Smith, C.

Smith, C. M.

Spielmann, C.

M. Lenzner, J. Krugler, S. Sartania, Z. Cheng, C. Spielmann, W. Kautek, and F. Krausz, “Femtosecond optical breakdown in dielectrics,” Phys. Rev. Lett. 80, 4076–4079 (1998).
[CrossRef]

Squier, J.

D. Du, X. Liu, G. Korn, J. Squier, and G. Mourou, “Laser-induced breakdown by impact ionization on silica with pulse widths from 7-ns to 150-fs,” Appl. Phys. Lett. 64, 3071–3073 (1994).
[CrossRef]

Streltsov, A.

Sudrie, L.

L. Sudrie, M. Franco, B. Prade, and A. Mysyrowicz, “Writing of permanent birefringent microlayers in bulk fused silica with femtosecond laser pulses,” Opt. Commun. 171, 279–284 (1999).
[CrossRef]

Vicanek, M.

A. Kaiser, B. Rethfeld, M. Vicanek, and G. Simon, “Microscopic processes in dielectrics under irradiation by subpicosecond laser pulses,” Phys. Rev. B 61, 11, 437–11, 450 (2000).
[CrossRef]

Appl. Opt. (1)

Appl. Phys. Lett. (1)

D. Du, X. Liu, G. Korn, J. Squier, and G. Mourou, “Laser-induced breakdown by impact ionization on silica with pulse widths from 7-ns to 150-fs,” Appl. Phys. Lett. 64, 3071–3073 (1994).
[CrossRef]

J. Lightwave Technol. (1)

K. O. Hill and G. Meltz, “Fiber Bragg grating technology fundamentals and overview,” J. Lightwave Technol. 15, 1263–1267 (1997).
[CrossRef]

J. Non-Cryst. Solids (1)

K. Hirao and K. Miura, “Writing waveguides and gratings in silica and related materials by a femtosecond laser,” J. Non-Cryst. Solids 239, 91–95 (1998).
[CrossRef]

J. Opt. Soc. Am. B (1)

Meas. Sci. Technol. (1)

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, 1784–1794 (2001).
[CrossRef]

Opt. Commun. (1)

L. Sudrie, M. Franco, B. Prade, and A. Mysyrowicz, “Writing of permanent birefringent microlayers in bulk fused silica with femtosecond laser pulses,” Opt. Commun. 171, 279–284 (1999).
[CrossRef]

Opt. Lett. (4)

Phys. Rev. B (1)

A. Kaiser, B. Rethfeld, M. Vicanek, and G. Simon, “Microscopic processes in dielectrics under irradiation by subpicosecond laser pulses,” Phys. Rev. B 61, 11, 437–11, 450 (2000).
[CrossRef]

Phys. Rev. Lett. (1)

M. Lenzner, J. Krugler, S. Sartania, Z. Cheng, C. Spielmann, W. Kautek, and F. Krausz, “Femtosecond optical breakdown in dielectrics,” Phys. Rev. Lett. 80, 4076–4079 (1998).
[CrossRef]

Sov. Phys. JETP (1)

L. V. Keldysh, “Ionization in the field of a strong em wave,” Sov. Phys. JETP 20, 1307–1314 (1965).

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Figures (11)

Fig. 1
Fig. 1

Typical refractive-index profile for a guiding structure written under optimal conditions.

Fig. 2
Fig. 2

Dependence of induced refractive index change in silica (Corning HPFS) on (a) translation velocity with fixed pulse energy 1 µJ and (b) laser-pulse energy with fixed velocity 10 µm/s (dashed curve, estimated temperature rise).

Fig. 3
Fig. 3

Dependence of induced refractive-index change in borosilicate glass on (a) translation velocity with 1-µJ fixed pulse energy and (b) laser-pulse energy with fixed 10-µm/s velocity (dashed curve, estimated temperature rise).

Fig. 4
Fig. 4

Light scattering from a damaged waveguide written with an excessive exposure (see text).

Fig. 5
Fig. 5

Measured nonlinear absorbance as a function of incident energy per pulse at 800 nm. Code 7890 is borosilicate.

Fig. 6
Fig. 6

Comparison of calculated (solid curve) and measured absorbed energy densities (squares) as a function of incident field strength for silica.

Fig. 7
Fig. 7

Temperature dependence of Δn of waveguides written the different protocols and wavelengths listed in the inset: ampl., amplifier.

Fig. 8
Fig. 8

Temperature dependence of the dominant color-center defect for (a) silica and (b) borosilicate glass compared with generalized induced index behavior from Fig. 7.

Fig. 9
Fig. 9

(a) Stress birefringence profiles of exposed tracks under crossed polarizers; the photograph shows the intensity pattern under crossed polarizers. (b) Measure of the birefringence along the dashed line shown in (a).

Fig. 10
Fig. 10

Calculated refractive-index change caused by compaction versus translation velocity for the measured birefringence data for two exposure levels: circles, 1 µJ; squares, 0.5 µJ.

Fig. 11
Fig. 11

Micro-Raman spectrum of exposed tracks as a function of exposure pulse energy. Traces are displaced vertically for comparison. The lowest trace is for unexposed glass; traces for exposures of 1, 2, and 4 µJ are also shown. The writing speed was 20 µm/s.

Tables (4)

Tables Icon

Table 1 Comparison of the Exposure Protocols Used in This Studya

Tables Icon

Table 2 Measured Nonlinear Absorption of Fused Silica at 800 nm

Tables Icon

Table 3 Measured Nonlinear Absorption of Borosilicate

Tables Icon

Table 4 Measured Concentration of Color Centers After Exposure

Equations (3)

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dnedt=W(I, ϖ, Δ)+ηIne,
W=σ(k)Ik,
γ=ΩmredΔeE,

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