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Optical Materials Express

Optical Materials Express

  • Editor: David J. Hagan
  • Vol. 1, Iss. 5 — Sep. 1, 2011
  • pp: 832–844
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Role of the 1D optical filamentation process in the writing of first order fiber Bragg gratings with femtosecond pulses at 800nm [Invited]

Martin Bernier, Stephan Gagnon, and Réal Vallée  »View Author Affiliations


Optical Materials Express, Vol. 1, Issue 5, pp. 832-844 (2011)
http://dx.doi.org/10.1364/OME.1.000832


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Abstract

The role of the optical filamentation of ultra-short infrared pulses at 800nm in the inscription of highly reflective and low loss fundamental order fiber Bragg gratings is investigated. The onset of the filamentation process is first evidenced through the observation of the spectra of both supercontinuum generation and plasma emission as well as through the precise measurement of the plasma-induced refractive index change. Typical samples of FBG obtained with this approach are presented.

© 2011 OSA

1. Introduction

The fabrication of fiber Bragg gratings (FBGs) based on the use of ultraviolet (UV) exposure either holographically [1

1. G. Meltz, W. W. Morey, and W. H. Glenn, “Formation of Bragg gratings in optical fibers by a transverse holographic method,” Opt. Lett. 14(15), 823–825 (1989). [CrossRef] [PubMed]

] or through a phase mask [2

2. K. O. Hill, B. Malo, F. Bilodeau, D. C. Johnson, and J. Albert, “Bragg gratings fabricated in monomode photosensitive optical fiber by UV exposure through a phase mask,” Appl. Phys. Lett. 62(10), 1035–1037 (1993). [CrossRef]

] has significantly evolved during the two last decades. The underlying physical process relies on the activation of a resonant defect associated with the presence of germanium in the fiber core. More recently, refractive index modifications of a different type (i.e. non-resonant) have been produced in various transparent materials based on the use of intense infrared femtosecond pulses. This approach has shown great promise for the fabrication of versatile photonic structures, such as waveguides, couplers, and gratings, in two or three dimensions [3

3. K. M. Davis, K. Miura, N. Sugimoto, and K. Hirao, “Writing waveguides in glass with a femtosecond laser,” Opt. Lett. 21(21), 1729–1731 (1996). [CrossRef] [PubMed]

,4

4. L. Sudrie, M. Franco, B. Prade, and A. Mysyrowicz, “Study of damage in fused silica induced by ultra-short IR laser pulses,” Opt. Commun. 191(3-6), 333–339 (2001). [CrossRef]

]. For instance, long period gratings were fabricated by focusing infrared pulses in single mode fibers using the point-by-point (PbP) irradiation technique [5

5. Y. Kondo, K. Nouchi, T. Mitsuyu, M. Watanabe, P. G. Kazansky, and K. Hirao, “Fabrication of long-period fiber gratings by focused irradiation of infrared femtosecond laser pulses,” Opt. Lett. 24(10), 646–648 (1999). [CrossRef] [PubMed]

]. Index changes as high as 6 x 10−3 were achieved in standard Ge-doped telecom fibers [6

6. E. Fertein, C. Przygodzki, H. Delbarre, A. Hidayat, M. Douay, and P. Niay, “Refractive-index changes of standard telecommunication fiber through exposure to femtosecond laser pulses at 810cm,” Appl. Opt. 40(21), 3506–3508 (2001). [CrossRef] [PubMed]

]. This technique was further developed and the writing of FBGs was also demonstrated [7

7. A. Martinez, M. Dubov, I. Khrushchev, and I. Bennion, “Direct writing of fiber Bragg gratings by femtosecond laser,” Electron. Lett. 40(19), 1170–1172 (2004). [CrossRef]

]. An alternative approach based on the interference of ultrashort pulses was developed to inscribe periodic structures in glass through a precise control of the interference pattern. Surface relief holographic gratings were first recorded on silica glass by interfering two infrared femtosecond pulsed beams [8

8. K. I. Kawamura, N. Sarukura, M. Hirano, and S. Hosono, “Holographic encoding of fine-pitched micrograting structures in amorphous SiO2 thin films on silicon by a single femtosecond laser pulse,” Appl. Phys. Lett. 78(8), 1038–1040 (2001). [CrossRef]

]. The use of a phase-mask was further demonstrated to be an efficient and robust method to write FBGs using 266nm [9

9. A. Dragomir, D. N. Nikogosyan, K. A. Zagorulko, P. G. Kryukov, and E. M. Dianov, “Inscription of fiber Bragg gratings by ultraviolet femtosecond radiation,” Opt. Lett. 28(22), 2171–2173 (2003). [CrossRef] [PubMed]

], 400nm [10

10. M. Bernier, R. Vallée, B. Morasse, C. Desrosiers, A. Saliminia, and Y. Sheng, “Ytterbium fiber laser based on first-order fiber Bragg gratings written with 400 nm femtosecond pulses and a phase-mask,” Opt. Express 17(21), 18887–18893 (2009). [CrossRef] [PubMed]

] and 800nm [11

11. S. J. Mihailov, C. W. Smelser, P. Lu, R. B. Walker, D. Grobnic, H. Ding, G. Henderson, and J. Unruh, “Fiber bragg gratings made with a phase mask and 800-nm femtosecond radiation,” Opt. Lett. 28(12), 995–997 (2003). [CrossRef] [PubMed]

] femtosecond pulses. Some interesting properties of this approach were demonstrated such as the capability of writing FBGs in various transparent materials such as pure and germanium-doped silica, phosphate, sapphire, lithium niobate, borosilicate [12

12. S. J. Mihailov, D. Grobnic, C. W. Smelser, P. Lu, R. B. Walker, and H. Ding, “Induced Bragg gratings in optical fibers and waveguides using an ultrafast infrared laser and a phase mask,” Laser Chem. 2008, 416251 (2008). [CrossRef]

], doped and undoped fluoride [13

13. M. Bernier, D. Faucher, R. Vallée, A. Saliminia, G. Androz, Y. Sheng, and S. L. Chin, “Bragg gratings photoinduced in ZBLAN fibers by femtosecond pulses at 800 nm,” Opt. Lett. 32(5), 454–456 (2007). [CrossRef] [PubMed]

], germanate, tellurite [14

14. R. Suo, J. Lousteau, H. Li, X. Jiang, K. Zhou, L. Zhang, W. N. MacPherson, H. T. Bookey, J. S. Barton, A. K. Kar, A. Jha, and I. Bennion, “Fiber Bragg gratings inscribed using 800nm femtosecond laser and a phase mask in single- and multi-core mid-IR glass fibers,” Opt. Express 17(9), 7540–7548 (2009). [CrossRef] [PubMed]

] and more recently in ytterbium-doped silica [10

10. M. Bernier, R. Vallée, B. Morasse, C. Desrosiers, A. Saliminia, and Y. Sheng, “Ytterbium fiber laser based on first-order fiber Bragg gratings written with 400 nm femtosecond pulses and a phase-mask,” Opt. Express 17(21), 18887–18893 (2009). [CrossRef] [PubMed]

] for high-power fiber laser purposes. The high refractive index modulation (up to 5x10−3) resulting from this approach allowed the writing of high-reflectivity (95%) ultrabroadband (310 nm) FBGs in standard silica fibers [15

15. M. Bernier, Y. Sheng, and R. Vallée, “Ultrabroadband fiber Bragg gratings written with a highly chirped phase mask and infrared femtosecond pulses,” Opt. Express 17(5), 3285–3290 (2009). [CrossRef] [PubMed]

]. FBGs of type I associated with glass densification and type II associated with induced damage were fabricated in silica fiber using the phase-mask technique and infrared femtosecond pulses under different input beam energies [16

16. C. W. Smelser, S. J. Mihailov, and D. Grobnic, “Formation of Type I-IR and Type II-IR gratings with an ultrafast IR laser and a phase mask,” Opt. Express 13(14), 5377–5386 (2005). [CrossRef] [PubMed]

].

In parallel to this, the optical filamentation of intense femtosecond pulses has attracted a lot of interest in the scientific community. The possibility of self-guiding a laser beam in air confined at a scale of 80 µm over 20 meters was first demonstrated by Braun et al [17

17. A. Braun, G. Korn, X. Liu, D. Du, J. Squier, and G. Mourou, “Self-channeling of high-peak-power femtosecond laser pulses in air,” Opt. Lett. 20(1), 73–75 (1995). [CrossRef] [PubMed]

] and was explained by a balance between Kerr self-focusing and defocusing by laser-induced electron plasma. It was further proposed that such phenomenon could be interpreted as the result of a moving focus along the filament [18

18. A. Brodeur, C. Y. Chien, F. A. Ilkov, S. L. Chin, O. G. Kosareva, and V. P. Kandidov, “Moving focus in the propagation of ultrashort laser pulses in air,” Opt. Lett. 22(5), 304–306 (1997). [CrossRef] [PubMed]

]. The emission of white light intimately associated with the filamentation process was also interpreted as the result of nonlinear effects that cause the conical emission of light [19

19. O. G. Kosareva, V. P. Kandidov, A. Brodeur, C. Y. Chien, and S. L. Chin, “Conical emission from laser plasma interactions in the filamentation of powerful ultrashort laser pulses in air,” Opt. Lett. 22(17), 1332–1334 (1997). [CrossRef] [PubMed]

]. The filamentation of infrared femtosecond pulses in condensed matter was also investigated. The self-guided propagation of the beam was first observed in fused silica [20

20. S. Tzortzakis, L. Bergé, A. Couairon, M. Franco, B. Prade, and A. Mysyrowicz, “Breakup and fusion of self-guided femtosecond light pulses in air,” Phys. Rev. Lett. 86(24), 5470–5473 (2001). [CrossRef] [PubMed]

] and the resulting plasma-channel was associated with a permanent refractive index modification of type I inside of the bulk silica [21

21. K. Yamada, W. Watanabe, T. Toma, K. Itoh, and J. Nishii, “In situ observation of photoinduced refractive-index changes in filaments formed in glasses by femtosecond laser pulses,” Opt. Lett. 26(1), 19–21 (2001). [CrossRef] [PubMed]

]. It was further reported that depending on the focusing conditions and the input beam energy, different regimes can take place. Accordingly, a filamentation regime resulting in a smooth refractive index modification (type I) is likely to occur for loose focusing conditions whereas damage is generally induced inside of the bulk (type II) for tight focusing [22

22. N. T. Nguyen, A. Saliminia, W. Liu, S. L. Chin, and R. Vallée, “Optical breakdown versus filamentation in fused silica by use of femtosecond infrared laser pulses,” Opt. Lett. 28(17), 1591–1593 (2003). [CrossRef] [PubMed]

]. A detailed description of the filamentation process and its consequences on optical media was also reported [23

23. S. L. Chin, S. A. Hosseini, W. Liu, Q. Luo, F. Theberge, N. Aközbek, A. Becker, V. P. Kandidov, O. G. Kosareva, and H. Schroeder, “The propagation of powerful femtosecond laser pulses in optical media: physics, applications, and new challenges,” Can. J. Phys. 83(9), 863–905 (2005). [CrossRef]

]. When the input pulse power is sufficiently large compared to the critical power for self-focusing, the multi-filamentation process takes place resulting in a generally erratic spatial distribution of the filaments. However, it was found that the input beam ellipticity could affect the positioning of each filament [24

24. A. Dubietis, G. Tamosauskas, G. Fibich, and B. Ilan, “Multiple filamentation induced by input-beam ellipticity,” Opt. Lett. 29(10), 1126–1128 (2004). [CrossRef] [PubMed]

] so that the use of a highly elliptical input beam could lead to the formation of a quasi-periodic arrangement of the filaments [25

25. D. Majus, V. Jukna, G. Valiulis, and A. Dubietis, “Generation of periodic filament arrays by self-focusing of highly elliptical ultrashort pulsed laser beams,” Phys. Rev. A 79(3), 033843 (2009). [CrossRef]

]. Based on this idea, it was shown that the multi-filamentation process could be precisely controlled by superimposing an interference pattern to the elliptical input beam with the use of a 1-D diffractive element. In this manner permanent refractive index modifications were induced in fused silica blocks with a perfectly controlled pitch size of 47 µm [26

26. J. P. Bérubé, R. Vallée, M. Bernier, O. G. Kosareva, N. Panov, V. Kandidov, and S. L. Chin, “Self and forced periodic arrangement of multiple filaments in glass,” Opt. Express 18(3), 1801–1819 (2010). [CrossRef] [PubMed]

].

In this paper, we demonstrate that the multi-filamentation of a highly elliptical focused beam can be precisely controlled in a periodic fashion using an interference pattern of short period (~0.5 µm). Loose focusing (i.e. f = 112mm) of ultrashort (34 fs) infrared femtosecond pulses at 1kHz in conjunction with a phase-mask will be shown to produce low loss and high-reflectivity first-order FBGs at 1.55 µm in standard SMF28 fibers as well as in fluoride fibers.

2. Experiment

A Ti-sapphire regenerative amplifier system (Coherent, model Legend-HE) that produced pulses with 3.5 mJ of energy at 1 kHz repetition rate with a central wavelength of λ = 806 nm was used. Temporal width of the Fourier-transform limited pulses was measured to be ~34 fs. The pulse width was enlarged to ~60 fs due to the group velocity dispersion when passing through the beam steering optical components. The laser beam was enlarged to ~8.5 mm x 20 mm size (at 1/e2) thanks to a cylindrical telescope. The beam was then focused using a cylindrical lens with a focal length of 112 mm through a uniform silica phase mask onto the fiber positioned along the focal line and in close proximity to the phase mask. The uniform phase mask with a pitch of 1070nm was fabricated by holographic lithography on a UV-grade fused silica substrate. The zero order of diffraction at 800 nm for polarization perpendicular to the grooves is 14%. Such a bad zero-order nullification is hindered by the group velocity walk-off effect [27

27. C. W. Smelser, D. Grobnic, and S. J. Mihailov, “Generation of pure two-beam interference grating structures in an optical fiber with a femtosecond infrared source and a phase mask,” Opt. Lett. 29(15), 1730–1732 (2004). [CrossRef] [PubMed]

] that spatially separates the zero from the ± 1 orders after a short propagation distance of the fs laser pulses beyond the phase-mask. A pure two beam interference pattern can be obtained after a propagation of about 50-75 μm from the phase-mask. We place the fiber at 125 μm from the phase mask to ensure that the walk-off condition is respected. Based on Gaussian beam optics, the width of the focal spot is 2w ~1.27f λ/2w0 ~14 μm, where λ is the wavelength, f is the focal length, and w0 represents the input beam radius (8.5mm at 1/e2) perpendicular to the fiber axis. Figure 1
Fig. 1 Sketch of the experimental setup used to write FBGs.
shows the sketch of the experimental setup used to write the FBGs.

Transmission and reflection spectra were measured in real-time using a broadband ASE light source together with an optical circulator and spectrum analyzer. After exposure, the fibers were cut through the center of the gratings and an optical fiber analyzer (NR-9200HR, EXFO) operating at 657 nm based on the refracted-near-field (RNF) technique was utilized to measure the cross-sectional (i.e. across the cleaved end-face) index profile averaged over a depth of approximately 1200 grating periods. The variation of refractive index modulation as a function of the annealing temperature was also measured using a specially designed fiber optic oven (ASP-500C).

3. Analysis of the Filamentation Process in a Coreless Fiber

3.1 Spectra Emitted during Filamentation Process

Two distinct types of light emission are associated with the filamentation process in condensed matter: supercontinuum generation which is almost collinear with the pump pulse and plasma emission [22

22. N. T. Nguyen, A. Saliminia, W. Liu, S. L. Chin, and R. Vallée, “Optical breakdown versus filamentation in fused silica by use of femtosecond infrared laser pulses,” Opt. Lett. 28(17), 1591–1593 (2003). [CrossRef] [PubMed]

] which results from electron recombination within the filament. These two types of light emission were thus analyzed as a function of the input pulse energy. Supercontinuum light emission was monitored along beam propagation using both a camera and a screen whereas plasma emission was detected from the light guided through the coreless fiberoptic. In both cases an optical spectrum analyzer OSA (Ando AQ-6315A) was used to monitor the spectra. Figure 2
Fig. 2 Far-field images of the supercontinuum (generated along the ± 1 diffracted orders) resulting from the filamentation process for input pulse energies of (a) 0.25mJ, (b) 0.5mJ, (c) 1.0mJ and (d) 1.75mJ.
presents the far-field images of the two diffracted beams after their propagation through the 200 µm diameter fiber. Note that a pump rejection filter (absorbing from 750nm to 900nm) was introduced in order to observe only the new frequencies generated by the nonlinear processes. Starting at pulse energies of 0.5 mJ the two diffracted beams (corresponding to orders ± 1 of the phase mask) take the form of a rather typical although distorted conical emission.

3.2 Direct Observation of the filaments

The dc refractive index change induced by the periodic filaments was characterized using a refracted near-field based instrument (EXFO, NR-9200HR) allowing a spatial resolution of 0.4 µm and a refractive index change resolution of about 5x10−5. Prior to measurement the 200 µm diameter coreless fiber was cleaved in the middle of its exposed region. The measurement performed on the resulting cleaved facet then provides the dc refractive index change averaged over a depth of ~600 µm (i.e. ~1200 grating periods). Two sets of measurements were carried out: 1) as a function of input pulse energy for a fixed exposure time; 2) as a function of exposure time for fixed input pulse energy. Figure 4
Fig. 4 Cross section traces of dc refractive index changes inscribed in the 200 µm diameter fiber and cleaved in the middle of the FBG after 60 s exposure and for input pulse energies ranging between 0.25mJ and 2.0 mJ.
presents the results obtained for different input pulse energies at 60 s exposure. A relatively short filament is first observed (marked with a red arrow which also indicates laser propagation direction) for a pulse energy of 0.5mJ. The filament rapidly lengthens while the energy per pulse is increased until a splitting occurs for E≥1.0mJ. A closer view of the bifurcated filament obtained for E = 1.0mJ is shown on Fig. 5(a)
Fig. 5 (a) Three dimensional view of the trace of the refractive index change at 1.0mJ for 30 s. (b) Filament transverse profile corresponding to position where the dc refractive index change is maximal (i.e. at 50 µm from the input fiber face) for a pulse energy of 1.0mJ and 30s exposure.
.

One first notes that a maximum refractive index change of the order of 2x10−3 is reached prior to the trace splitting. Two asymmetrical branches result from the splitting, with one bearing a significantly reduced refractive index change. Clearly, the trace left by the femtosecond pulse arises from an asymmetrical spatial splitting. At this point, the precise mechanism leading to such pulse break-up is not fully understood. Clearly though, the overall extent of the trace is of the order of 100µm, for the case shown here, whereas its width appears to remain essentially constant throughout the entire propagation distance, therefore evidencing the filamentary nature of the process. In fact, the filament width is always of the order of 1µm and does not appear to vary much, neither along the filament nor as a function of the pulse energy or exposure time. Figure 5(b) shows a typical transverse profile of a filament obtained for 30s exposure at 1.0mJ.

We have performed an exhaustive analysis of the filament parameters for various inscription conditions. The maximum dc refractive index change as well as the filament length are shown on Fig. 6
Fig. 6 (a) Maximum dc refractive index change and, (b) filament length as a function of the input pulse energy for an exposure time of 60s. (c) Maximum dc refractive index change and, (d) filament length as a function of exposure for 1.0 mJ pulse energy.
.

4. Filamentation in a Core Fiber

We have thus exposed standard SMF28 fibers under similar inscription conditions. Prior to exposure, the focus was precisely positioned with respect to the fiber core. We exposed SMF28 fiber samples to different input pulse energies and measured the induced dc refractive index change in the same manner as described for the coreless fiber case. Figure 7
Fig. 7 Refractive index profiles of hydrogen-free SMF28 fibers exposed at pulse energies of 0.5, 1.25 and 2.0mJ for an exposure time of 20s. The laser pulse is arriving from the left.
shows the photo-induced refractive index variations for input energies of 0.5, 1.25 and 2.0 mJ. Note that the size of the elliptical beam incident on the cylindrical focusing lens was slightly smaller than that used in the coreless fiber case (i.e 5mm X 7.5mm). A relatively short filament is first observed for a pulse energy of 0.5mJ. Now this filament is not positioned so as to overlap with the fiber core so that it does not actually contribute to the inscription of an FBG but simply to a periodic modulation of the refractive index within the cladding. (Note that since the core and the cladding are both photosensitive to intense femtosecond pulses (as opposed to the UV radiation case) the threshold of the underlying photosensitive process does not necessarily correspond to the experimentally observed onset of FBG writing.) For a pulse energy of 1.25mJ the filament length is of the order of 70 µm but is barely touching the core. At 2.0mJ multi-filamentation is taking place at the fiber’s rear surface but one of the sub-filaments is subsequently hitting the core and vanishing soon after. Now it was observed that the fiber samples are weakened when the filament reaches the glass surface so that we can conclude that, for the current focusing geometry, energy per pulse should remain of the order of 1mJ in agreement with the results previously obtained for the coreless fiber. A corollary to this is that the filament propagation is affected by the core which contributes to reduce its length. This phenomenon is actually enhanced in the case of a hydrogen-loaded core as shown on Fig. 8
Fig. 8 Contour plot of the dc refractive index change of a hydrogen-loaded SMF28 fiber exposed at a pulse energy of 1.4 mJ for 60s.
.

One sees that upon crossing the fiber core the filament is not only broadened but essentially stopped by it. The presence of germanium in the fiber core would most likely explain this behavior. Accordingly, one notes that the refractive index change is of the order of 10x10−3 in the core area whereas it is limited to 5x10−3 in the cladding supporting the idea that both glass densification and color centers are contributing to the femtosecond pulse-induced photosensitive process.

5. Analysis

6. FBGs In Silica and Fluoride Fibers based on the Filamentation Process

Maximum refractive index modulations of 2.7x10−3 and 5.5x10−3 are obtained in hydrogen-free and hydrogen-loaded fibers respectively. One can observe that the maximum refractive index modulation (ac component) in hydrogen-free SMF28 fiber is close to the maximum dc refractive index change obtained under the same exposure conditions in pure silica fibers (cf. Fig. 6(c)). We also proceeded to a thermal annealing of FBGs inscribed in both hydrogen-loaded and hydrogen-free fiber using a fiber optic oven up to 500°C. The annealing curves are presented at Fig. 12
Fig. 12 Variation of index modulation as a function of annealing temperature for gratings written in H2-free and H2-loaded fibers with an initial non-saturated refractive index modulation of about 5x10−4. The fibers were annealed for 30 min. at each temperature.
. The normalized refractive index modulation (inferred from the FBG transmission spectrum) corresponding to the H2-loaded case shows a rapid drop for temperatures up to 300°C whereas, beyond this temperature, the two curves decrease with the same slope. This would indicate that a fraction of about 40% of the refractive index change in the H2-loaded case arises from color centers. Also note that 80% of the index modulation remains at 500°C in the unloaded case which is consistent with glass densification pertaining to Type I grating.

In order to inscribe improved quality FBGs, the length of the exposure beam was increased from 20mm to 50mm and the corresponding input beam energy was consequently increased from 1.0mJ to 2.5mJ in order to maintain the same writing conditions. The FBG exposure length was limited to L = 25mm (over a total length of 50mm at 1/e2) with a calibrated slit to obtain an almost uniform intensity profile in order to obtain a uniform FBG spectral shape.

Figure 13(a)
Fig. 13 (a) Reflection and transmission spectra for an unsaturated FBG written in a hydrogen-free SMF28 fiber at 2.5mJ, a length of 25mm and an exposure time of 10 s. (b) Transmission spectrum for an FBG written in a 2000ppm Tm3+-doped ZBLAN fiber at 2.5mJ, a length of 25mm and an exposure time of 20 s.
shows the reflection and transmission spectra of an unsaturated FBG written in a hydrogen-free SMF28 fiber for an exposure time of 10s and input pulse energy of 2.5mJ. An FBG was also inscribed under the same exposure conditions in a 2000ppm Tm3+-doped ZBLAN fiber for 20s. The corresponding transmission spectrum is presented in Fig. 13(b).

The gray losses of these two −50dB reflectivity FBGs are lower than 0.02dB and 0.35 dB for the silica and the fluoride fibers respectively. Also note that, as a direct consequence of the photosensitivity of the cladding to femtosecond pulses, cladding-mode losses remain very low with less than 1.0dB and 0.5dB for the silica and the fluoride fibers respectively. The preceding results represent quite well the huge potential of femtosecond pulses in the filamentation regime to write high quality first-order FBGs in various materials.

7. Conclusion

We have provided a new physical insight on the 1D filamentation process allowing for the inscription of high quality first-order FBGs with femtosecond pulses and a phase mask. Average photo-induced dc and ac refractive index changes of the order of 5x10−3 were shown to arise from this process. The validity of the approach is illustrated with the inscription of −50dB FBGs in both silica and fluoride glass fibers.

Acknowledgments

This research was supported by the Canadian Institute for Photonic Innovations (CIPI), the Fonds Quebecois de la Recherche sur la Nature et les Technologies (FQNRT), the Natural Science and Engineering Research Council of Canada (NSERC) and the Canada Foundation for Innovation (CFI). The authors would also like to thank Prof. See Leang Chin for helpful discussions, Martin Laprise and Michael Dallaire for technical support.

References and links

1.

G. Meltz, W. W. Morey, and W. H. Glenn, “Formation of Bragg gratings in optical fibers by a transverse holographic method,” Opt. Lett. 14(15), 823–825 (1989). [CrossRef] [PubMed]

2.

K. O. Hill, B. Malo, F. Bilodeau, D. C. Johnson, and J. Albert, “Bragg gratings fabricated in monomode photosensitive optical fiber by UV exposure through a phase mask,” Appl. Phys. Lett. 62(10), 1035–1037 (1993). [CrossRef]

3.

K. M. Davis, K. Miura, N. Sugimoto, and K. Hirao, “Writing waveguides in glass with a femtosecond laser,” Opt. Lett. 21(21), 1729–1731 (1996). [CrossRef] [PubMed]

4.

L. Sudrie, M. Franco, B. Prade, and A. Mysyrowicz, “Study of damage in fused silica induced by ultra-short IR laser pulses,” Opt. Commun. 191(3-6), 333–339 (2001). [CrossRef]

5.

Y. Kondo, K. Nouchi, T. Mitsuyu, M. Watanabe, P. G. Kazansky, and K. Hirao, “Fabrication of long-period fiber gratings by focused irradiation of infrared femtosecond laser pulses,” Opt. Lett. 24(10), 646–648 (1999). [CrossRef] [PubMed]

6.

E. Fertein, C. Przygodzki, H. Delbarre, A. Hidayat, M. Douay, and P. Niay, “Refractive-index changes of standard telecommunication fiber through exposure to femtosecond laser pulses at 810cm,” Appl. Opt. 40(21), 3506–3508 (2001). [CrossRef] [PubMed]

7.

A. Martinez, M. Dubov, I. Khrushchev, and I. Bennion, “Direct writing of fiber Bragg gratings by femtosecond laser,” Electron. Lett. 40(19), 1170–1172 (2004). [CrossRef]

8.

K. I. Kawamura, N. Sarukura, M. Hirano, and S. Hosono, “Holographic encoding of fine-pitched micrograting structures in amorphous SiO2 thin films on silicon by a single femtosecond laser pulse,” Appl. Phys. Lett. 78(8), 1038–1040 (2001). [CrossRef]

9.

A. Dragomir, D. N. Nikogosyan, K. A. Zagorulko, P. G. Kryukov, and E. M. Dianov, “Inscription of fiber Bragg gratings by ultraviolet femtosecond radiation,” Opt. Lett. 28(22), 2171–2173 (2003). [CrossRef] [PubMed]

10.

M. Bernier, R. Vallée, B. Morasse, C. Desrosiers, A. Saliminia, and Y. Sheng, “Ytterbium fiber laser based on first-order fiber Bragg gratings written with 400 nm femtosecond pulses and a phase-mask,” Opt. Express 17(21), 18887–18893 (2009). [CrossRef] [PubMed]

11.

S. J. Mihailov, C. W. Smelser, P. Lu, R. B. Walker, D. Grobnic, H. Ding, G. Henderson, and J. Unruh, “Fiber bragg gratings made with a phase mask and 800-nm femtosecond radiation,” Opt. Lett. 28(12), 995–997 (2003). [CrossRef] [PubMed]

12.

S. J. Mihailov, D. Grobnic, C. W. Smelser, P. Lu, R. B. Walker, and H. Ding, “Induced Bragg gratings in optical fibers and waveguides using an ultrafast infrared laser and a phase mask,” Laser Chem. 2008, 416251 (2008). [CrossRef]

13.

M. Bernier, D. Faucher, R. Vallée, A. Saliminia, G. Androz, Y. Sheng, and S. L. Chin, “Bragg gratings photoinduced in ZBLAN fibers by femtosecond pulses at 800 nm,” Opt. Lett. 32(5), 454–456 (2007). [CrossRef] [PubMed]

14.

R. Suo, J. Lousteau, H. Li, X. Jiang, K. Zhou, L. Zhang, W. N. MacPherson, H. T. Bookey, J. S. Barton, A. K. Kar, A. Jha, and I. Bennion, “Fiber Bragg gratings inscribed using 800nm femtosecond laser and a phase mask in single- and multi-core mid-IR glass fibers,” Opt. Express 17(9), 7540–7548 (2009). [CrossRef] [PubMed]

15.

M. Bernier, Y. Sheng, and R. Vallée, “Ultrabroadband fiber Bragg gratings written with a highly chirped phase mask and infrared femtosecond pulses,” Opt. Express 17(5), 3285–3290 (2009). [CrossRef] [PubMed]

16.

C. W. Smelser, S. J. Mihailov, and D. Grobnic, “Formation of Type I-IR and Type II-IR gratings with an ultrafast IR laser and a phase mask,” Opt. Express 13(14), 5377–5386 (2005). [CrossRef] [PubMed]

17.

A. Braun, G. Korn, X. Liu, D. Du, J. Squier, and G. Mourou, “Self-channeling of high-peak-power femtosecond laser pulses in air,” Opt. Lett. 20(1), 73–75 (1995). [CrossRef] [PubMed]

18.

A. Brodeur, C. Y. Chien, F. A. Ilkov, S. L. Chin, O. G. Kosareva, and V. P. Kandidov, “Moving focus in the propagation of ultrashort laser pulses in air,” Opt. Lett. 22(5), 304–306 (1997). [CrossRef] [PubMed]

19.

O. G. Kosareva, V. P. Kandidov, A. Brodeur, C. Y. Chien, and S. L. Chin, “Conical emission from laser plasma interactions in the filamentation of powerful ultrashort laser pulses in air,” Opt. Lett. 22(17), 1332–1334 (1997). [CrossRef] [PubMed]

20.

S. Tzortzakis, L. Bergé, A. Couairon, M. Franco, B. Prade, and A. Mysyrowicz, “Breakup and fusion of self-guided femtosecond light pulses in air,” Phys. Rev. Lett. 86(24), 5470–5473 (2001). [CrossRef] [PubMed]

21.

K. Yamada, W. Watanabe, T. Toma, K. Itoh, and J. Nishii, “In situ observation of photoinduced refractive-index changes in filaments formed in glasses by femtosecond laser pulses,” Opt. Lett. 26(1), 19–21 (2001). [CrossRef] [PubMed]

22.

N. T. Nguyen, A. Saliminia, W. Liu, S. L. Chin, and R. Vallée, “Optical breakdown versus filamentation in fused silica by use of femtosecond infrared laser pulses,” Opt. Lett. 28(17), 1591–1593 (2003). [CrossRef] [PubMed]

23.

S. L. Chin, S. A. Hosseini, W. Liu, Q. Luo, F. Theberge, N. Aközbek, A. Becker, V. P. Kandidov, O. G. Kosareva, and H. Schroeder, “The propagation of powerful femtosecond laser pulses in optical media: physics, applications, and new challenges,” Can. J. Phys. 83(9), 863–905 (2005). [CrossRef]

24.

A. Dubietis, G. Tamosauskas, G. Fibich, and B. Ilan, “Multiple filamentation induced by input-beam ellipticity,” Opt. Lett. 29(10), 1126–1128 (2004). [CrossRef] [PubMed]

25.

D. Majus, V. Jukna, G. Valiulis, and A. Dubietis, “Generation of periodic filament arrays by self-focusing of highly elliptical ultrashort pulsed laser beams,” Phys. Rev. A 79(3), 033843 (2009). [CrossRef]

26.

J. P. Bérubé, R. Vallée, M. Bernier, O. G. Kosareva, N. Panov, V. Kandidov, and S. L. Chin, “Self and forced periodic arrangement of multiple filaments in glass,” Opt. Express 18(3), 1801–1819 (2010). [CrossRef] [PubMed]

27.

C. W. Smelser, D. Grobnic, and S. J. Mihailov, “Generation of pure two-beam interference grating structures in an optical fiber with a femtosecond infrared source and a phase mask,” Opt. Lett. 29(15), 1730–1732 (2004). [CrossRef] [PubMed]

28.

A. Brodeur and S. L. Chin, “Ultrafast white-light continuum generation and self-focusing in transparent condensed media,” J. Opt. Soc. Am. B 16(4), 637–650 (1999). [CrossRef]

29.

H. B. Sun, S. Juodkazis, M. Watanabe, S. Matsuo, H. Misawa, and J. Nishii, “Generation and recombination of defects in vitreous silica induced by irradiation with a near-infrared femtosecond laser,” J. Phys. Chem. B 104(15), 3450–3455 (2000). [CrossRef]

30.

W. Liu, S. Petit, A. Becker, N. Aközbek, C. M. Bowden, and S. L. Chin, “Intensity clamping of a femtosecond laser pulse in condensed matter,” Opt. Commun. 202(1-3), 189–197 (2002). [CrossRef]

31.

A. Barthelemy, S. Maneuf, and C. Froehly, “Soliton propagation and self-trapping of laser beams by a Kerr optical nonlinearity,” Opt. Commun. 55(3), 201–206 (1985). [CrossRef]

32.

G. P. Agrawal, Applications of Nonlinear Fiber Optics (Academic Press, 2001).

OCIS Codes
(190.7110) Nonlinear optics : Ultrafast nonlinear optics
(230.1480) Optical devices : Bragg reflectors
(060.3738) Fiber optics and optical communications : Fiber Bragg gratings, photosensitivity

ToC Category:
Laser Materials Processing

History
Original Manuscript: June 28, 2011
Revised Manuscript: July 28, 2011
Manuscript Accepted: July 29, 2011
Published: August 3, 2011

Virtual Issues
Femtosecond Direct Laser Writing and Structuring of Materials (2011) Optical Materials Express

Citation
Martin Bernier, Stephan Gagnon, and Réal Vallée, "Role of the 1D optical filamentation process in the writing of first order fiber Bragg gratings with femtosecond pulses at 800nm [Invited]," Opt. Mater. Express 1, 832-844 (2011)
http://www.opticsinfobase.org/ome/abstract.cfm?URI=ome-1-5-832


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References

  1. G. Meltz, W. W. Morey, and W. H. Glenn, “Formation of Bragg gratings in optical fibers by a transverse holographic method,” Opt. Lett. 14(15), 823–825 (1989). [CrossRef] [PubMed]
  2. K. O. Hill, B. Malo, F. Bilodeau, D. C. Johnson, and J. Albert, “Bragg gratings fabricated in monomode photosensitive optical fiber by UV exposure through a phase mask,” Appl. Phys. Lett. 62(10), 1035–1037 (1993). [CrossRef]
  3. K. M. Davis, K. Miura, N. Sugimoto, and K. Hirao, “Writing waveguides in glass with a femtosecond laser,” Opt. Lett. 21(21), 1729–1731 (1996). [CrossRef] [PubMed]
  4. L. Sudrie, M. Franco, B. Prade, and A. Mysyrowicz, “Study of damage in fused silica induced by ultra-short IR laser pulses,” Opt. Commun. 191(3-6), 333–339 (2001). [CrossRef]
  5. Y. Kondo, K. Nouchi, T. Mitsuyu, M. Watanabe, P. G. Kazansky, and K. Hirao, “Fabrication of long-period fiber gratings by focused irradiation of infrared femtosecond laser pulses,” Opt. Lett. 24(10), 646–648 (1999). [CrossRef] [PubMed]
  6. E. Fertein, C. Przygodzki, H. Delbarre, A. Hidayat, M. Douay, and P. Niay, “Refractive-index changes of standard telecommunication fiber through exposure to femtosecond laser pulses at 810cm,” Appl. Opt. 40(21), 3506–3508 (2001). [CrossRef] [PubMed]
  7. A. Martinez, M. Dubov, I. Khrushchev, and I. Bennion, “Direct writing of fiber Bragg gratings by femtosecond laser,” Electron. Lett. 40(19), 1170–1172 (2004). [CrossRef]
  8. K. I. Kawamura, N. Sarukura, M. Hirano, and S. Hosono, “Holographic encoding of fine-pitched micrograting structures in amorphous SiO2 thin films on silicon by a single femtosecond laser pulse,” Appl. Phys. Lett. 78(8), 1038–1040 (2001). [CrossRef]
  9. A. Dragomir, D. N. Nikogosyan, K. A. Zagorulko, P. G. Kryukov, and E. M. Dianov, “Inscription of fiber Bragg gratings by ultraviolet femtosecond radiation,” Opt. Lett. 28(22), 2171–2173 (2003). [CrossRef] [PubMed]
  10. M. Bernier, R. Vallée, B. Morasse, C. Desrosiers, A. Saliminia, and Y. Sheng, “Ytterbium fiber laser based on first-order fiber Bragg gratings written with 400 nm femtosecond pulses and a phase-mask,” Opt. Express 17(21), 18887–18893 (2009). [CrossRef] [PubMed]
  11. S. J. Mihailov, C. W. Smelser, P. Lu, R. B. Walker, D. Grobnic, H. Ding, G. Henderson, and J. Unruh, “Fiber bragg gratings made with a phase mask and 800-nm femtosecond radiation,” Opt. Lett. 28(12), 995–997 (2003). [CrossRef] [PubMed]
  12. S. J. Mihailov, D. Grobnic, C. W. Smelser, P. Lu, R. B. Walker, and H. Ding, “Induced Bragg gratings in optical fibers and waveguides using an ultrafast infrared laser and a phase mask,” Laser Chem. 2008, 416251 (2008). [CrossRef]
  13. M. Bernier, D. Faucher, R. Vallée, A. Saliminia, G. Androz, Y. Sheng, and S. L. Chin, “Bragg gratings photoinduced in ZBLAN fibers by femtosecond pulses at 800 nm,” Opt. Lett. 32(5), 454–456 (2007). [CrossRef] [PubMed]
  14. R. Suo, J. Lousteau, H. Li, X. Jiang, K. Zhou, L. Zhang, W. N. MacPherson, H. T. Bookey, J. S. Barton, A. K. Kar, A. Jha, and I. Bennion, “Fiber Bragg gratings inscribed using 800nm femtosecond laser and a phase mask in single- and multi-core mid-IR glass fibers,” Opt. Express 17(9), 7540–7548 (2009). [CrossRef] [PubMed]
  15. M. Bernier, Y. Sheng, and R. Vallée, “Ultrabroadband fiber Bragg gratings written with a highly chirped phase mask and infrared femtosecond pulses,” Opt. Express 17(5), 3285–3290 (2009). [CrossRef] [PubMed]
  16. C. W. Smelser, S. J. Mihailov, and D. Grobnic, “Formation of Type I-IR and Type II-IR gratings with an ultrafast IR laser and a phase mask,” Opt. Express 13(14), 5377–5386 (2005). [CrossRef] [PubMed]
  17. A. Braun, G. Korn, X. Liu, D. Du, J. Squier, and G. Mourou, “Self-channeling of high-peak-power femtosecond laser pulses in air,” Opt. Lett. 20(1), 73–75 (1995). [CrossRef] [PubMed]
  18. A. Brodeur, C. Y. Chien, F. A. Ilkov, S. L. Chin, O. G. Kosareva, and V. P. Kandidov, “Moving focus in the propagation of ultrashort laser pulses in air,” Opt. Lett. 22(5), 304–306 (1997). [CrossRef] [PubMed]
  19. O. G. Kosareva, V. P. Kandidov, A. Brodeur, C. Y. Chien, and S. L. Chin, “Conical emission from laser plasma interactions in the filamentation of powerful ultrashort laser pulses in air,” Opt. Lett. 22(17), 1332–1334 (1997). [CrossRef] [PubMed]
  20. S. Tzortzakis, L. Bergé, A. Couairon, M. Franco, B. Prade, and A. Mysyrowicz, “Breakup and fusion of self-guided femtosecond light pulses in air,” Phys. Rev. Lett. 86(24), 5470–5473 (2001). [CrossRef] [PubMed]
  21. K. Yamada, W. Watanabe, T. Toma, K. Itoh, and J. Nishii, “In situ observation of photoinduced refractive-index changes in filaments formed in glasses by femtosecond laser pulses,” Opt. Lett. 26(1), 19–21 (2001). [CrossRef] [PubMed]
  22. N. T. Nguyen, A. Saliminia, W. Liu, S. L. Chin, and R. Vallée, “Optical breakdown versus filamentation in fused silica by use of femtosecond infrared laser pulses,” Opt. Lett. 28(17), 1591–1593 (2003). [CrossRef] [PubMed]
  23. S. L. Chin, S. A. Hosseini, W. Liu, Q. Luo, F. Theberge, N. Aközbek, A. Becker, V. P. Kandidov, O. G. Kosareva, and H. Schroeder, “The propagation of powerful femtosecond laser pulses in optical media: physics, applications, and new challenges,” Can. J. Phys. 83(9), 863–905 (2005). [CrossRef]
  24. A. Dubietis, G. Tamosauskas, G. Fibich, and B. Ilan, “Multiple filamentation induced by input-beam ellipticity,” Opt. Lett. 29(10), 1126–1128 (2004). [CrossRef] [PubMed]
  25. D. Majus, V. Jukna, G. Valiulis, and A. Dubietis, “Generation of periodic filament arrays by self-focusing of highly elliptical ultrashort pulsed laser beams,” Phys. Rev. A 79(3), 033843 (2009). [CrossRef]
  26. J. P. Bérubé, R. Vallée, M. Bernier, O. G. Kosareva, N. Panov, V. Kandidov, and S. L. Chin, “Self and forced periodic arrangement of multiple filaments in glass,” Opt. Express 18(3), 1801–1819 (2010). [CrossRef] [PubMed]
  27. C. W. Smelser, D. Grobnic, and S. J. Mihailov, “Generation of pure two-beam interference grating structures in an optical fiber with a femtosecond infrared source and a phase mask,” Opt. Lett. 29(15), 1730–1732 (2004). [CrossRef] [PubMed]
  28. A. Brodeur and S. L. Chin, “Ultrafast white-light continuum generation and self-focusing in transparent condensed media,” J. Opt. Soc. Am. B 16(4), 637–650 (1999). [CrossRef]
  29. H. B. Sun, S. Juodkazis, M. Watanabe, S. Matsuo, H. Misawa, and J. Nishii, “Generation and recombination of defects in vitreous silica induced by irradiation with a near-infrared femtosecond laser,” J. Phys. Chem. B 104(15), 3450–3455 (2000). [CrossRef]
  30. W. Liu, S. Petit, A. Becker, N. Aközbek, C. M. Bowden, and S. L. Chin, “Intensity clamping of a femtosecond laser pulse in condensed matter,” Opt. Commun. 202(1-3), 189–197 (2002). [CrossRef]
  31. A. Barthelemy, S. Maneuf, and C. Froehly, “Soliton propagation and self-trapping of laser beams by a Kerr optical nonlinearity,” Opt. Commun. 55(3), 201–206 (1985). [CrossRef]
  32. G. P. Agrawal, Applications of Nonlinear Fiber Optics (Academic Press, 2001).

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