Abstract

A method for fabricating microlenses in polycarbonate material is reported. Using a direct-write technique based on scanning excimer laser ablation with a circular beam, we can etch an arbitrary shape in the polymer material. The beam is obtained by imaging a circular aperture onto the polymer surface, and scanning is realized by the translation stage carrying the sample, which makes successive contours with well-chosen diameters and scan velocities. Afterward, to smooth the ablated surface and release it from debris, a large beam aperture covering the full lens area is used to ablate the lens deeper into the substrate. The fabrication process and the characterization method are described, including calculation of the contour set for a desired lens shape. The optical performance is evaluated by Mach–Zehnder interferometry, showing that aberrations below λ/10 are possible for slow lenses.

© 2003 Optical Society of America

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  1. M. Gale, M. Rossi, J. Pedersen, H. Schütz, “Fabrication of continuous micro-optical elements by direct laser writing in photoresists,” Opt. Eng. 33, 3556–3566 (1994).
    [CrossRef]
  2. W. Cox, C. Guan, D. Hayes, “Microjet printing of micro-optical interconnects and sensors,” in Optoelectronic Interconnects VII; Photonics Packaging and Integration II, M. Feldman, R. Li, W. Matkin, S. Tang, eds., Proc. SPIE3952, 400–407 (2000).
    [CrossRef]
  3. X. Wang, J. R. Leger, R. H. Rediker, “Rapid fabrication of diffractive optical elements by use of image-based excimer laser ablation,” Appl. Opt. 36, 4660–4665 (1997).
    [CrossRef] [PubMed]
  4. R. Matz, H. Weber, G. Weimann, “Laser-induced dry etching of integrated InP microlenses,” Appl. Phys. A 65, 349–353 (1997).
    [CrossRef]
  5. S. Mihailov, S. Lazare, “Fabrication of refractive microlens arrays by excimer laser ablation of amorphous Teflon,” Appl. Opt. 32, 6211–6218 (1993).
    [CrossRef] [PubMed]
  6. S. Lazare, J. Lopez, J.-M. Turlet, M. Kufner, S. Kufner, P. Chavel, “Microlenses fabricated by ultraviolet excimer laser irradiation of poly(methyl methacrylate) followed by styrene diffusion,” Appl. Opt. 35, 4471–4475 (1996).
    [CrossRef] [PubMed]
  7. F. Beinhorn, J. Ihlemann, K. Luther, J. Troe, “Microlens arrays generated by UV laser irradiation of doped PMMA,” Appl. Phys. A 68, 709–713 (1999).
    [CrossRef]
  8. T. Jitsuno, K. Tokumura, N. Nakashima, M. Nakatsuka, “Laser ablative shaping of plastic optical components for phase control,” Appl. Opt. 38, 3338–3342 (1999).
    [CrossRef]
  9. M. Wakaki, Y. Komachi, G. Kanai, “Microlenses and microlens arrays formed on a glass plate by use of a CO2 laser,” Appl. Opt. 37, 627–631 (1998).
    [CrossRef]
  10. K. Naessens, P. Van Daele, R. Baets, “Laser-ablation-based technique for flexible fabrication of microlenses in polymer materials,” in Second International Symposium on Laser Precision Microfabrication, I. Miyamoto, Y. Feng Lu, K. Sugioka, J. Dubowski, eds., Proc. SPIE4426, 124–127 (2001).
    [CrossRef]
  11. K. Naessens, P. Van Daele, R. Baets, “Excimer laser ablation based microlens fabrication for optical fiber coupling purposes,” in Laser Micromachining for Optoelectronic Device Fabrication, A. Ostendorf, eds., Proc. SPIE4941, 133–139 (2002).
    [CrossRef]
  12. T. Berden, E. Kreutz, R. Poprawe, “Debris-reduced laser machining of polymeric waveguides for optoelectronic applications,” in Laser Applications in Microelectronic and Optoelectronic Manufacturing VI, M. Gower, H. Helvajian, K. Sugioka, J. Dubowski, eds., Proc. SPIE4274, 432–441 (2001).
    [CrossRef]
  13. R. Srinivasan, B. Braren, K. Casey, “Nature of incubation pulses in the ultraviolet laser ablation of polymethyl methacrylate,” J. Appl. Phys. 68, 1842–1847 (1990).
    [CrossRef]
  14. B. Hopp, M. Csete, K. Revesz, J. Vinko, Z. Bor, “Formation of the surface structure of polyethylene-therephtalate (PET) due to ArF excimer laser ablation,” Appl. Surf. Sci. 96-8, 611–616 (1996).
    [CrossRef]
  15. F. Burns, S. Cain, “The effect of pulse repetition rate on laser ablation of polyimide and poly(methyl methacrylate) based polymers,” J. Appl. Phys. 29, 1349–1355 (1996).

1999 (2)

F. Beinhorn, J. Ihlemann, K. Luther, J. Troe, “Microlens arrays generated by UV laser irradiation of doped PMMA,” Appl. Phys. A 68, 709–713 (1999).
[CrossRef]

T. Jitsuno, K. Tokumura, N. Nakashima, M. Nakatsuka, “Laser ablative shaping of plastic optical components for phase control,” Appl. Opt. 38, 3338–3342 (1999).
[CrossRef]

1998 (1)

1997 (2)

1996 (3)

B. Hopp, M. Csete, K. Revesz, J. Vinko, Z. Bor, “Formation of the surface structure of polyethylene-therephtalate (PET) due to ArF excimer laser ablation,” Appl. Surf. Sci. 96-8, 611–616 (1996).
[CrossRef]

F. Burns, S. Cain, “The effect of pulse repetition rate on laser ablation of polyimide and poly(methyl methacrylate) based polymers,” J. Appl. Phys. 29, 1349–1355 (1996).

S. Lazare, J. Lopez, J.-M. Turlet, M. Kufner, S. Kufner, P. Chavel, “Microlenses fabricated by ultraviolet excimer laser irradiation of poly(methyl methacrylate) followed by styrene diffusion,” Appl. Opt. 35, 4471–4475 (1996).
[CrossRef] [PubMed]

1994 (1)

M. Gale, M. Rossi, J. Pedersen, H. Schütz, “Fabrication of continuous micro-optical elements by direct laser writing in photoresists,” Opt. Eng. 33, 3556–3566 (1994).
[CrossRef]

1993 (1)

1990 (1)

R. Srinivasan, B. Braren, K. Casey, “Nature of incubation pulses in the ultraviolet laser ablation of polymethyl methacrylate,” J. Appl. Phys. 68, 1842–1847 (1990).
[CrossRef]

Baets, R.

K. Naessens, P. Van Daele, R. Baets, “Laser-ablation-based technique for flexible fabrication of microlenses in polymer materials,” in Second International Symposium on Laser Precision Microfabrication, I. Miyamoto, Y. Feng Lu, K. Sugioka, J. Dubowski, eds., Proc. SPIE4426, 124–127 (2001).
[CrossRef]

K. Naessens, P. Van Daele, R. Baets, “Excimer laser ablation based microlens fabrication for optical fiber coupling purposes,” in Laser Micromachining for Optoelectronic Device Fabrication, A. Ostendorf, eds., Proc. SPIE4941, 133–139 (2002).
[CrossRef]

Beinhorn, F.

F. Beinhorn, J. Ihlemann, K. Luther, J. Troe, “Microlens arrays generated by UV laser irradiation of doped PMMA,” Appl. Phys. A 68, 709–713 (1999).
[CrossRef]

Berden, T.

T. Berden, E. Kreutz, R. Poprawe, “Debris-reduced laser machining of polymeric waveguides for optoelectronic applications,” in Laser Applications in Microelectronic and Optoelectronic Manufacturing VI, M. Gower, H. Helvajian, K. Sugioka, J. Dubowski, eds., Proc. SPIE4274, 432–441 (2001).
[CrossRef]

Bor, Z.

B. Hopp, M. Csete, K. Revesz, J. Vinko, Z. Bor, “Formation of the surface structure of polyethylene-therephtalate (PET) due to ArF excimer laser ablation,” Appl. Surf. Sci. 96-8, 611–616 (1996).
[CrossRef]

Braren, B.

R. Srinivasan, B. Braren, K. Casey, “Nature of incubation pulses in the ultraviolet laser ablation of polymethyl methacrylate,” J. Appl. Phys. 68, 1842–1847 (1990).
[CrossRef]

Burns, F.

F. Burns, S. Cain, “The effect of pulse repetition rate on laser ablation of polyimide and poly(methyl methacrylate) based polymers,” J. Appl. Phys. 29, 1349–1355 (1996).

Cain, S.

F. Burns, S. Cain, “The effect of pulse repetition rate on laser ablation of polyimide and poly(methyl methacrylate) based polymers,” J. Appl. Phys. 29, 1349–1355 (1996).

Casey, K.

R. Srinivasan, B. Braren, K. Casey, “Nature of incubation pulses in the ultraviolet laser ablation of polymethyl methacrylate,” J. Appl. Phys. 68, 1842–1847 (1990).
[CrossRef]

Chavel, P.

Cox, W.

W. Cox, C. Guan, D. Hayes, “Microjet printing of micro-optical interconnects and sensors,” in Optoelectronic Interconnects VII; Photonics Packaging and Integration II, M. Feldman, R. Li, W. Matkin, S. Tang, eds., Proc. SPIE3952, 400–407 (2000).
[CrossRef]

Csete, M.

B. Hopp, M. Csete, K. Revesz, J. Vinko, Z. Bor, “Formation of the surface structure of polyethylene-therephtalate (PET) due to ArF excimer laser ablation,” Appl. Surf. Sci. 96-8, 611–616 (1996).
[CrossRef]

Gale, M.

M. Gale, M. Rossi, J. Pedersen, H. Schütz, “Fabrication of continuous micro-optical elements by direct laser writing in photoresists,” Opt. Eng. 33, 3556–3566 (1994).
[CrossRef]

Guan, C.

W. Cox, C. Guan, D. Hayes, “Microjet printing of micro-optical interconnects and sensors,” in Optoelectronic Interconnects VII; Photonics Packaging and Integration II, M. Feldman, R. Li, W. Matkin, S. Tang, eds., Proc. SPIE3952, 400–407 (2000).
[CrossRef]

Hayes, D.

W. Cox, C. Guan, D. Hayes, “Microjet printing of micro-optical interconnects and sensors,” in Optoelectronic Interconnects VII; Photonics Packaging and Integration II, M. Feldman, R. Li, W. Matkin, S. Tang, eds., Proc. SPIE3952, 400–407 (2000).
[CrossRef]

Hopp, B.

B. Hopp, M. Csete, K. Revesz, J. Vinko, Z. Bor, “Formation of the surface structure of polyethylene-therephtalate (PET) due to ArF excimer laser ablation,” Appl. Surf. Sci. 96-8, 611–616 (1996).
[CrossRef]

Ihlemann, J.

F. Beinhorn, J. Ihlemann, K. Luther, J. Troe, “Microlens arrays generated by UV laser irradiation of doped PMMA,” Appl. Phys. A 68, 709–713 (1999).
[CrossRef]

Jitsuno, T.

Kanai, G.

Komachi, Y.

Kreutz, E.

T. Berden, E. Kreutz, R. Poprawe, “Debris-reduced laser machining of polymeric waveguides for optoelectronic applications,” in Laser Applications in Microelectronic and Optoelectronic Manufacturing VI, M. Gower, H. Helvajian, K. Sugioka, J. Dubowski, eds., Proc. SPIE4274, 432–441 (2001).
[CrossRef]

Kufner, M.

Kufner, S.

Lazare, S.

Leger, J. R.

Lopez, J.

Luther, K.

F. Beinhorn, J. Ihlemann, K. Luther, J. Troe, “Microlens arrays generated by UV laser irradiation of doped PMMA,” Appl. Phys. A 68, 709–713 (1999).
[CrossRef]

Matz, R.

R. Matz, H. Weber, G. Weimann, “Laser-induced dry etching of integrated InP microlenses,” Appl. Phys. A 65, 349–353 (1997).
[CrossRef]

Mihailov, S.

Naessens, K.

K. Naessens, P. Van Daele, R. Baets, “Excimer laser ablation based microlens fabrication for optical fiber coupling purposes,” in Laser Micromachining for Optoelectronic Device Fabrication, A. Ostendorf, eds., Proc. SPIE4941, 133–139 (2002).
[CrossRef]

K. Naessens, P. Van Daele, R. Baets, “Laser-ablation-based technique for flexible fabrication of microlenses in polymer materials,” in Second International Symposium on Laser Precision Microfabrication, I. Miyamoto, Y. Feng Lu, K. Sugioka, J. Dubowski, eds., Proc. SPIE4426, 124–127 (2001).
[CrossRef]

Nakashima, N.

Nakatsuka, M.

Pedersen, J.

M. Gale, M. Rossi, J. Pedersen, H. Schütz, “Fabrication of continuous micro-optical elements by direct laser writing in photoresists,” Opt. Eng. 33, 3556–3566 (1994).
[CrossRef]

Poprawe, R.

T. Berden, E. Kreutz, R. Poprawe, “Debris-reduced laser machining of polymeric waveguides for optoelectronic applications,” in Laser Applications in Microelectronic and Optoelectronic Manufacturing VI, M. Gower, H. Helvajian, K. Sugioka, J. Dubowski, eds., Proc. SPIE4274, 432–441 (2001).
[CrossRef]

Rediker, R. H.

Revesz, K.

B. Hopp, M. Csete, K. Revesz, J. Vinko, Z. Bor, “Formation of the surface structure of polyethylene-therephtalate (PET) due to ArF excimer laser ablation,” Appl. Surf. Sci. 96-8, 611–616 (1996).
[CrossRef]

Rossi, M.

M. Gale, M. Rossi, J. Pedersen, H. Schütz, “Fabrication of continuous micro-optical elements by direct laser writing in photoresists,” Opt. Eng. 33, 3556–3566 (1994).
[CrossRef]

Schütz, H.

M. Gale, M. Rossi, J. Pedersen, H. Schütz, “Fabrication of continuous micro-optical elements by direct laser writing in photoresists,” Opt. Eng. 33, 3556–3566 (1994).
[CrossRef]

Srinivasan, R.

R. Srinivasan, B. Braren, K. Casey, “Nature of incubation pulses in the ultraviolet laser ablation of polymethyl methacrylate,” J. Appl. Phys. 68, 1842–1847 (1990).
[CrossRef]

Tokumura, K.

Troe, J.

F. Beinhorn, J. Ihlemann, K. Luther, J. Troe, “Microlens arrays generated by UV laser irradiation of doped PMMA,” Appl. Phys. A 68, 709–713 (1999).
[CrossRef]

Turlet, J.-M.

Van Daele, P.

K. Naessens, P. Van Daele, R. Baets, “Laser-ablation-based technique for flexible fabrication of microlenses in polymer materials,” in Second International Symposium on Laser Precision Microfabrication, I. Miyamoto, Y. Feng Lu, K. Sugioka, J. Dubowski, eds., Proc. SPIE4426, 124–127 (2001).
[CrossRef]

K. Naessens, P. Van Daele, R. Baets, “Excimer laser ablation based microlens fabrication for optical fiber coupling purposes,” in Laser Micromachining for Optoelectronic Device Fabrication, A. Ostendorf, eds., Proc. SPIE4941, 133–139 (2002).
[CrossRef]

Vinko, J.

B. Hopp, M. Csete, K. Revesz, J. Vinko, Z. Bor, “Formation of the surface structure of polyethylene-therephtalate (PET) due to ArF excimer laser ablation,” Appl. Surf. Sci. 96-8, 611–616 (1996).
[CrossRef]

Wakaki, M.

Wang, X.

Weber, H.

R. Matz, H. Weber, G. Weimann, “Laser-induced dry etching of integrated InP microlenses,” Appl. Phys. A 65, 349–353 (1997).
[CrossRef]

Weimann, G.

R. Matz, H. Weber, G. Weimann, “Laser-induced dry etching of integrated InP microlenses,” Appl. Phys. A 65, 349–353 (1997).
[CrossRef]

Appl. Opt. (5)

Appl. Phys. A (2)

F. Beinhorn, J. Ihlemann, K. Luther, J. Troe, “Microlens arrays generated by UV laser irradiation of doped PMMA,” Appl. Phys. A 68, 709–713 (1999).
[CrossRef]

R. Matz, H. Weber, G. Weimann, “Laser-induced dry etching of integrated InP microlenses,” Appl. Phys. A 65, 349–353 (1997).
[CrossRef]

Appl. Surf. Sci. (1)

B. Hopp, M. Csete, K. Revesz, J. Vinko, Z. Bor, “Formation of the surface structure of polyethylene-therephtalate (PET) due to ArF excimer laser ablation,” Appl. Surf. Sci. 96-8, 611–616 (1996).
[CrossRef]

J. Appl. Phys. (2)

F. Burns, S. Cain, “The effect of pulse repetition rate on laser ablation of polyimide and poly(methyl methacrylate) based polymers,” J. Appl. Phys. 29, 1349–1355 (1996).

R. Srinivasan, B. Braren, K. Casey, “Nature of incubation pulses in the ultraviolet laser ablation of polymethyl methacrylate,” J. Appl. Phys. 68, 1842–1847 (1990).
[CrossRef]

Opt. Eng. (1)

M. Gale, M. Rossi, J. Pedersen, H. Schütz, “Fabrication of continuous micro-optical elements by direct laser writing in photoresists,” Opt. Eng. 33, 3556–3566 (1994).
[CrossRef]

Other (4)

W. Cox, C. Guan, D. Hayes, “Microjet printing of micro-optical interconnects and sensors,” in Optoelectronic Interconnects VII; Photonics Packaging and Integration II, M. Feldman, R. Li, W. Matkin, S. Tang, eds., Proc. SPIE3952, 400–407 (2000).
[CrossRef]

K. Naessens, P. Van Daele, R. Baets, “Laser-ablation-based technique for flexible fabrication of microlenses in polymer materials,” in Second International Symposium on Laser Precision Microfabrication, I. Miyamoto, Y. Feng Lu, K. Sugioka, J. Dubowski, eds., Proc. SPIE4426, 124–127 (2001).
[CrossRef]

K. Naessens, P. Van Daele, R. Baets, “Excimer laser ablation based microlens fabrication for optical fiber coupling purposes,” in Laser Micromachining for Optoelectronic Device Fabrication, A. Ostendorf, eds., Proc. SPIE4941, 133–139 (2002).
[CrossRef]

T. Berden, E. Kreutz, R. Poprawe, “Debris-reduced laser machining of polymeric waveguides for optoelectronic applications,” in Laser Applications in Microelectronic and Optoelectronic Manufacturing VI, M. Gower, H. Helvajian, K. Sugioka, J. Dubowski, eds., Proc. SPIE4274, 432–441 (2001).
[CrossRef]

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Figures (14)

Fig. 1
Fig. 1

Principle of scanning contour ablation.

Fig. 2
Fig. 2

Trench fabrication with scanning contour ablation: (a) relevant parameters for calculating the trench profile, (b) trench cross section with ϕ = 100 μm, k = 5.0 μm/s, ν = 10 μm/s, and (1), D = 50 μm, (2) D = 100 μm, (3) D = 200 μm.

Fig. 3
Fig. 3

(a) Comparison between the calculated profile and measured cross section for a structure consisting of two trenches with ϕ = 100 μm, D = 40 and 80 μm, ν = 50 μm/s, d = 0.084 μm per pulse, f = 20 Hz. (b) Surface of this structure, measured with confocal microscopy.

Fig. 4
Fig. 4

Calculated rms deviation of the approximating surface according to the cw model used in the optimization algorithm and according to the discrete-pulse approach for several maximum scan velocities. Calculations are valid for a 200-μm lens with R = 250 μm and on-target beam size of 100 μm.

Fig. 5
Fig. 5

Calculated three-dimensional image of (a) a cone structure and (b) the measured profile. Contour velocity and diameter ranges are 40–150 μm/s and 25–150 μm, respectively. After the process of scanning contour ablation, the cone was driven 11 μm deeper into the material to obtain a smooth surface.

Fig. 6
Fig. 6

Ablated cavities after 20 pulses of 47 mJ/cm2 with an ArF laser.

Fig. 7
Fig. 7

Microlens with R = 800 μm in polycarbonate: surface (a) after scanning contour ablation and (b) after laser smoothing.

Fig. 8
Fig. 8

(a) Lens surface for R = 125 μm, showing the radial groove pattern. (b) SEM image of another ablated lens (200 μm in diameter), showing clearer evidence of the irregular structure at the lens rim.

Fig. 9
Fig. 9

Typical phase distribution of a wavefront, measured right above the lens for an incident spherical wavefront entering the substrate from the focal plane.

Fig. 10
Fig. 10

(a) Root-mean-square values of wavefront aberrations ΔΨ of the ablated lenses and (b) their corresponding Strehl ratios for different focal lengths.

Fig. 11
Fig. 11

(a) Root-mean-square wavefront aberrations for different etch rates, averaged over all lenses and (b) lenses with f numbers of f/5.0 or higher.

Fig. 12
Fig. 12

Root-mean-square wavefront aberrations for different pulse rates, averaged over all lenses.

Fig. 13
Fig. 13

Root-mean-square wavefront aberrations for different contour velocity ranges.

Fig. 14
Fig. 14

Nonspherical and nonconvex lens shapes: (a) concave, (b) flat-topped parabolic lens, (c) 4 × 4 lens array fabricated with an array of apertures. The lenses have a 100-μm diameter and a pitch of 150 μm and are fabricated with a 50-μm beam aperture. The fill factor is 35%.

Tables (2)

Tables Icon

Table 1 Calculated Lens Characteristics for ν Range of 40–150 μm/s, f = 20 Hz, ϕ = 100 μm, d = 0.07 μm

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Table 2 Lens Properties Ablated with Fabrication Parametersa

Equations (4)

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yr=-apr
a=πDkν, pr=1π a cosD2+4r2-ϕ24rDifD-ϕ2<r<D+ϕ21ifϕ-D2<r0ifr<D-ϕ2, r>D+ϕ2.
ε=0Φ/2Yr-i yirn2πdr,
Yr=-offset+R-R2-r21/2

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