Abstract

A simple method of manufacturing micrometer-sized polymer elements at the extremity of both single-mode and multimode optical fibers is reported. The procedure consists of depositing a drop of a liquid photopolymerizable formulation on a cleaved fiber and using the light that emerges from the fiber to induce the polymerization process. After exposure and rinsing a polymer tip is firmly attached to the fiber as an extension of the fiber core. It is shown that the tip geometry can be adjusted by the variation of basic parameters such as the geometry of the deposited drop and the conditions of drop illumination. When this process is applied to a multimode fiber three-dimensional molds of the fiber’s linearly polarized modes can be obtained. The process of polymer-tip formation was simulated by a numerical calculation that consisted of an iterative beam-propagation method in a medium whose refractive index is time varying. It is shown that this process is based on the gradual growth, just above the fiber core, of an optical waveguide in the liquid formulation. Experimental data concerning two potential uses of the tipped fibers are presented.

© 2001 Optical Society of America

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References

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  1. D. Kato, “Light coupling from a stripe-geometry GaAs diode laser into an optical fiber with a spherical end,” J. Appl. Phys. 44, 2756–2758 (1973).
    [CrossRef]
  2. H. M. Presby, A. F. Benner, C. A. Edwards, “Laser micromaching of efficient fiber microlenses,” Appl. Opt. 29, 2692–2695 (1990).
    [CrossRef] [PubMed]
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    [CrossRef] [PubMed]
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    [CrossRef] [PubMed]
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    [CrossRef]
  7. N. S. Allen, ed., Photopolymerisation and Photoimaging Science and Technology (Elsevier Applied Science, London, UK, 1989).
    [CrossRef]
  8. C. Ecoffet, A. Espanet, D. J. Lougnot, “Photopolymerization by evanescent waves: a new method to obtain nanoparts,” Adv. Mater. 10, 411–414 (1998).
    [CrossRef]
  9. A. Espanet, “Photopolymerisation par les ondes evanescentes. Application à la stéreolithographie et au stokage optique de l’information,” Ph.D. dissertation (Université de Haute Alsace, Mulhouse, France, 1998).
  10. A. Espanet, C. Ecoffet, D. J. Lougnot, “Photopolymerization by evanescent waves. II: revealing dramatic inhibiting effects of oxygen at the submicrometer scale,” J. Polym. Sci. A: Polym. Chem. 3, 2075–2085 (1999).
  11. J. P. Fouassier, E. Chesneau, “Polymérisation sous irradiation laser visible,” Makromol. Chem. 492, 245–260 (1991).
    [CrossRef]
  12. J. E. Midwinter, Optical Fibers for Transmission (Krieger, Malabar, Fla., 1992), Chap. 7.
  13. D. J. Lougnot, “Les photopolymères,” in Techniques d’Application des Photons, J.-C. André, A.-B. Vannes, eds. (DOPEE85, Paris, 1995), pp. 245–304.
  14. T. Okoshi, S. Kitazama, “The beam propagation method,” in Analysis Methods for Electromagnetic Wave Problems, E. Yamashita, ed. (Artech House, Norwood, Mass., 1990), pp. 341–369.
  15. C. Ecoffet, M. Helle, Département de Nanotechnologie et d’Instrumentation Optique, Université de Technologie de Troyes, 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex, France (private communication, 2June2000).
  16. A. S. Kewitsch, A. Yariv, “Self-focusing and self-trapping of optical beams on photopolymerization,” Opt. Lett. 21, 24–26 (1996).
    [CrossRef] [PubMed]
  17. N. Fressengeas, “Etude expérimentale et théorique de l’auto focalisation d’un faisceau laser en milieu photoréfractif: convergences spatiale et temporelle vers un soliton,” Ph.D. dissertation (University of Metz, Metz, France, 1997).
  18. M. Born, E. Wolf, eds., Principles of Optics, 6th ed. (Pergamon, New York, 1993), Chap. 13.
  19. M. A. Paesler, P. J. Moyer, Near-Field Optics (Wiley, New York, 1996).
  20. J. P. Fillard, Near-Field Optics and Nanoscopy (World Scientific, Singapore, 1996).
    [CrossRef]
  21. Ch. Lienau, A. Richter, T. Elsaesser, “Light-induced expansion of fiber tips in near-field scanning optical microscopy,” Appl. Phys. Lett. 63, 325–327 (1996).
    [CrossRef]

1999 (1)

A. Espanet, C. Ecoffet, D. J. Lougnot, “Photopolymerization by evanescent waves. II: revealing dramatic inhibiting effects of oxygen at the submicrometer scale,” J. Polym. Sci. A: Polym. Chem. 3, 2075–2085 (1999).

1998 (1)

C. Ecoffet, A. Espanet, D. J. Lougnot, “Photopolymerization by evanescent waves: a new method to obtain nanoparts,” Adv. Mater. 10, 411–414 (1998).
[CrossRef]

1996 (2)

A. S. Kewitsch, A. Yariv, “Self-focusing and self-trapping of optical beams on photopolymerization,” Opt. Lett. 21, 24–26 (1996).
[CrossRef] [PubMed]

Ch. Lienau, A. Richter, T. Elsaesser, “Light-induced expansion of fiber tips in near-field scanning optical microscopy,” Appl. Phys. Lett. 63, 325–327 (1996).
[CrossRef]

1991 (1)

J. P. Fouassier, E. Chesneau, “Polymérisation sous irradiation laser visible,” Makromol. Chem. 492, 245–260 (1991).
[CrossRef]

1990 (1)

1985 (1)

1982 (1)

1980 (1)

1974 (1)

1973 (1)

D. Kato, “Light coupling from a stripe-geometry GaAs diode laser into an optical fiber with a spherical end,” J. Appl. Phys. 44, 2756–2758 (1973).
[CrossRef]

Barnes, F. S.

Bear, P. D.

Benner, A. F.

Chesneau, E.

J. P. Fouassier, E. Chesneau, “Polymérisation sous irradiation laser visible,” Makromol. Chem. 492, 245–260 (1991).
[CrossRef]

Cohen, L. G.

Ecoffet, C.

A. Espanet, C. Ecoffet, D. J. Lougnot, “Photopolymerization by evanescent waves. II: revealing dramatic inhibiting effects of oxygen at the submicrometer scale,” J. Polym. Sci. A: Polym. Chem. 3, 2075–2085 (1999).

C. Ecoffet, A. Espanet, D. J. Lougnot, “Photopolymerization by evanescent waves: a new method to obtain nanoparts,” Adv. Mater. 10, 411–414 (1998).
[CrossRef]

C. Ecoffet, M. Helle, Département de Nanotechnologie et d’Instrumentation Optique, Université de Technologie de Troyes, 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex, France (private communication, 2June2000).

Edwards, C. A.

Eisenstein, G.

Elsaesser, T.

Ch. Lienau, A. Richter, T. Elsaesser, “Light-induced expansion of fiber tips in near-field scanning optical microscopy,” Appl. Phys. Lett. 63, 325–327 (1996).
[CrossRef]

Espanet, A.

A. Espanet, C. Ecoffet, D. J. Lougnot, “Photopolymerization by evanescent waves. II: revealing dramatic inhibiting effects of oxygen at the submicrometer scale,” J. Polym. Sci. A: Polym. Chem. 3, 2075–2085 (1999).

C. Ecoffet, A. Espanet, D. J. Lougnot, “Photopolymerization by evanescent waves: a new method to obtain nanoparts,” Adv. Mater. 10, 411–414 (1998).
[CrossRef]

A. Espanet, “Photopolymerisation par les ondes evanescentes. Application à la stéreolithographie et au stokage optique de l’information,” Ph.D. dissertation (Université de Haute Alsace, Mulhouse, France, 1998).

Fillard, J. P.

J. P. Fillard, Near-Field Optics and Nanoscopy (World Scientific, Singapore, 1996).
[CrossRef]

Fouassier, J. P.

J. P. Fouassier, E. Chesneau, “Polymérisation sous irradiation laser visible,” Makromol. Chem. 492, 245–260 (1991).
[CrossRef]

Fressengeas, N.

N. Fressengeas, “Etude expérimentale et théorique de l’auto focalisation d’un faisceau laser en milieu photoréfractif: convergences spatiale et temporelle vers un soliton,” Ph.D. dissertation (University of Metz, Metz, France, 1997).

Helle, M.

C. Ecoffet, M. Helle, Département de Nanotechnologie et d’Instrumentation Optique, Université de Technologie de Troyes, 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex, France (private communication, 2June2000).

Kato, D.

D. Kato, “Light coupling from a stripe-geometry GaAs diode laser into an optical fiber with a spherical end,” J. Appl. Phys. 44, 2756–2758 (1973).
[CrossRef]

Kewitsch, A. S.

Kitazama, S.

T. Okoshi, S. Kitazama, “The beam propagation method,” in Analysis Methods for Electromagnetic Wave Problems, E. Yamashita, ed. (Artech House, Norwood, Mass., 1990), pp. 341–369.

Lee, K. S.

Lienau, Ch.

Ch. Lienau, A. Richter, T. Elsaesser, “Light-induced expansion of fiber tips in near-field scanning optical microscopy,” Appl. Phys. Lett. 63, 325–327 (1996).
[CrossRef]

Lougnot, D. J.

A. Espanet, C. Ecoffet, D. J. Lougnot, “Photopolymerization by evanescent waves. II: revealing dramatic inhibiting effects of oxygen at the submicrometer scale,” J. Polym. Sci. A: Polym. Chem. 3, 2075–2085 (1999).

C. Ecoffet, A. Espanet, D. J. Lougnot, “Photopolymerization by evanescent waves: a new method to obtain nanoparts,” Adv. Mater. 10, 411–414 (1998).
[CrossRef]

D. J. Lougnot, “Les photopolymères,” in Techniques d’Application des Photons, J.-C. André, A.-B. Vannes, eds. (DOPEE85, Paris, 1995), pp. 245–304.

Midwinter, J. E.

J. E. Midwinter, Optical Fibers for Transmission (Krieger, Malabar, Fla., 1992), Chap. 7.

Moyer, P. J.

M. A. Paesler, P. J. Moyer, Near-Field Optics (Wiley, New York, 1996).

Okoshi, T.

T. Okoshi, S. Kitazama, “The beam propagation method,” in Analysis Methods for Electromagnetic Wave Problems, E. Yamashita, ed. (Artech House, Norwood, Mass., 1990), pp. 341–369.

Paesler, M. A.

M. A. Paesler, P. J. Moyer, Near-Field Optics (Wiley, New York, 1996).

Presby, H. M.

Richter, A.

Ch. Lienau, A. Richter, T. Elsaesser, “Light-induced expansion of fiber tips in near-field scanning optical microscopy,” Appl. Phys. Lett. 63, 325–327 (1996).
[CrossRef]

Schneider, M. V.

Vitello, D.

Yariv, A.

Adv. Mater. (1)

C. Ecoffet, A. Espanet, D. J. Lougnot, “Photopolymerization by evanescent waves: a new method to obtain nanoparts,” Adv. Mater. 10, 411–414 (1998).
[CrossRef]

Appl. Opt. (5)

Appl. Phys. Lett. (1)

Ch. Lienau, A. Richter, T. Elsaesser, “Light-induced expansion of fiber tips in near-field scanning optical microscopy,” Appl. Phys. Lett. 63, 325–327 (1996).
[CrossRef]

J. Appl. Phys. (1)

D. Kato, “Light coupling from a stripe-geometry GaAs diode laser into an optical fiber with a spherical end,” J. Appl. Phys. 44, 2756–2758 (1973).
[CrossRef]

J. Polym. Sci. A: Polym. Chem. (1)

A. Espanet, C. Ecoffet, D. J. Lougnot, “Photopolymerization by evanescent waves. II: revealing dramatic inhibiting effects of oxygen at the submicrometer scale,” J. Polym. Sci. A: Polym. Chem. 3, 2075–2085 (1999).

Makromol. Chem. (1)

J. P. Fouassier, E. Chesneau, “Polymérisation sous irradiation laser visible,” Makromol. Chem. 492, 245–260 (1991).
[CrossRef]

Opt. Lett. (1)

Other (10)

N. Fressengeas, “Etude expérimentale et théorique de l’auto focalisation d’un faisceau laser en milieu photoréfractif: convergences spatiale et temporelle vers un soliton,” Ph.D. dissertation (University of Metz, Metz, France, 1997).

M. Born, E. Wolf, eds., Principles of Optics, 6th ed. (Pergamon, New York, 1993), Chap. 13.

M. A. Paesler, P. J. Moyer, Near-Field Optics (Wiley, New York, 1996).

J. P. Fillard, Near-Field Optics and Nanoscopy (World Scientific, Singapore, 1996).
[CrossRef]

A. Espanet, “Photopolymerisation par les ondes evanescentes. Application à la stéreolithographie et au stokage optique de l’information,” Ph.D. dissertation (Université de Haute Alsace, Mulhouse, France, 1998).

J. E. Midwinter, Optical Fibers for Transmission (Krieger, Malabar, Fla., 1992), Chap. 7.

D. J. Lougnot, “Les photopolymères,” in Techniques d’Application des Photons, J.-C. André, A.-B. Vannes, eds. (DOPEE85, Paris, 1995), pp. 245–304.

T. Okoshi, S. Kitazama, “The beam propagation method,” in Analysis Methods for Electromagnetic Wave Problems, E. Yamashita, ed. (Artech House, Norwood, Mass., 1990), pp. 341–369.

C. Ecoffet, M. Helle, Département de Nanotechnologie et d’Instrumentation Optique, Université de Technologie de Troyes, 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex, France (private communication, 2June2000).

N. S. Allen, ed., Photopolymerisation and Photoimaging Science and Technology (Elsevier Applied Science, London, UK, 1989).
[CrossRef]

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Figures (19)

Fig. 1
Fig. 1

Reticulation rate of the formulation plotted versus the absorbed energy. E th is the threshold energy (when it is achieved polymerization starts), and n is the refractive index of the formulation.

Fig. 2
Fig. 2

Experimental arrangement for exposing a drop of photopolymerizable formulation that is deposited over the core of an optical fiber.

Fig. 3
Fig. 3

Electron micrographs of the polymer tip that is formed over the core of a single-mode optical fiber. (a) A 150 µm × 118 µm image: the cleaved fiber surface of the polymer tip whose base coincides with the fiber core. (b) A 5.6 µm × 4.7 µm image showing the tip’s extremity.

Fig. 4
Fig. 4

Electron micrographs of the extremities of four tipped fibers that were fabricated with various exposure times: (a) 2 s, (b) 45 s, (c) 60 s, (d) 90 s.

Fig. 5
Fig. 5

Electron micrograph of (a), (b), (c) the extremities of three tipped fibers fabricated under the same exposure times as for Fig. 4(a).

Fig. 6
Fig. 6

Electron micrograph of a 2-µm-thick microlens fabricated over the fiber core.

Fig. 7
Fig. 7

Fabrication of the 3-D polymer molds of the LP modes of a multimode optical fiber. The objects are fabricated just over the fiber core. (a) Theoretical intensity distribution of the LP11 mode, (b) electron micrograph of the fabricated mold of the LP11 mode, (c) theoretical intensity distribution of the LP21 mode, (d) electron micrograph of the fabricated mold of the LP21 mode.

Fig. 8
Fig. 8

Numerical simulation of the formation of a polymer tip at the extremity of a single-mode fiber. The modification of the refractive index of the medium during tip formation is not taken into account. t, exposure time (arbitrary units).

Fig. 9
Fig. 9

Electron micrograph of a long-tip fiber that was obtained by the dipping of the fiber into a thick layer of the formulation.

Fig. 10
Fig. 10

Principle of the numerical calculation that permits the simulation of tip formation. See text for details.

Fig. 11
Fig. 11

Two-dimensional geometry of the calculation described in Fig. 10.

Fig. 12
Fig. 12

Threshold energy E th of the reticulation plotted versus the distance z from the fiber end. The formulation–air interface is at z = 30 µm.

Fig. 13
Fig. 13

Results of the calculation described in Fig. 10. Column 1 represents the refractive-index distribution plotted as a function of the exposure time t. The black outline represents the theoretical shape of the polymerized part if the modification of the refractive index is neglected. Column 2 shows the received energy Er. The white outlines correspond to the isoenergetic lines Er = 1 and Er = 10. These outlines are also represented in gray in column 1. If the threshold energy E th is not a function of the distance to the interface, i.e., if oxygen diffusion is neglected, the shape of the obtained tip must fit within the white outlines shown in column 2. Column 3 represents the instantaneous field intensity within the material, i.e., the result of the calculation of the beam propagation through the refractive-index distribution represented in column 1.

Fig. 14
Fig. 14

Electron micrograph of a polymer tip fabricated over the core of a single-mode fiber. The tip body shows a node, as predicted by the numerical results of Fig. 13.

Fig. 15
Fig. 15

Schematic of the visual observation of the light emerging from the tipped fiber.

Fig. 16
Fig. 16

Diagram of one use of the single-mode tipped fiber: imaging a laser diode in operation. The image is formed by SNOM of the tip above the laser diode parallel to the crystal’s output facet.

Fig. 17
Fig. 17

Results of the experiment depicted in Fig. 16. Shown are 8 µm × 8 µm optical images of the laser diode working in spontaneous-emission mode for various tip-to-diode distances: (a) ∼2.5 µm, (b) ∼1 µm, (c) ∼0.1 µm.

Fig. 18
Fig. 18

Diagram of one use of the LP21-mode tipped fiber: selective mode coupling. The tip is illuminated by a slightly converging Gaussian beam. The intensity distribution at the fiber output is recorded by a CCD camera. The tilt (θ x , θ y ) of the fiber can be adjusted.

Fig. 19
Fig. 19

Results of the experiment depicted in Fig. 18. The images reveal that the LP21 mode was easily and selectively coupled into the multimode fiber. Each image corresponds to a fiber tilt (θ x , θ y ) with respect to the incident beam. (a) Image obtained for optimal tilt: the coupling is strong. (b), (c) Images obtained with nonoptimal tilts: the coupling efficiency is not strong, but the LP21 mode is maintained.

Equations (11)

Equations on this page are rendered with MathJax. Learn more.

V=2πaNAλ0,
W0r=A exp-rw2,
w=λ0πNA.
Ix, y, z  Wx, y, zW*x, y, z,
Eabs=KWx, y, zW*x, y, zt,
Eth=KA2tth.
Eabs/Eth=Wx, y, zW*x, y, zA2ttth.
Er=0t |Wx, z, t|2dt,
FEr=dnEr=dnmax1-expEth-Erp,  ErEth,
Ethz=1-3 loge1-zd,  zd.
η= E1E2dxdy2 |E1|2dxdy  |E2|2dxdy,

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