Abstract

We report the design, fabrication, and measurement of high efficiency, compact 45° single air interface bends in low refractive index contrast waveguides in a low refractive index material system. Using standard microfabrication techniques, the bends are fabricated on silicon substrates using perfluorcyclobutyl (PFCB) copolymers, which feature a high glass transition temperature and low absorption loss. The measured 45° bends have a loss of 0.30±0.03dB/bend for TM polarization and 0.33±0.03dB/bend for TE polarization.

© 2004 Optical Society of America

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References

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  1. L.H. Spiekman, Y. S. O., E.G. Metaal, F.H. Groen, P. Demeester, M.K. Smit, "Ultrasmall waveguide bends: the corner mirrors of the future?" IEEE Proc. Optoelectron. 142, 61-65 (1995).
    [CrossRef]
  2. Milos Popovic, K. W., Shoji Akiyama, Hermann A. Haus, Jurgen Michel, "Air Trenches for Sharp Silica Waveguide Bends," J. Lightwave Technol. 20, 1762-1772 (2002).
    [CrossRef]
  3. Seunghyun Kim, Gregory P. Nordin., Jianhua Jiang, Jingbo Cai, "High Efficiency 90° Silica Waveguide Bend Using an Air Hole Photonic Crystal Region," IEEE Phot. Technol. Lett. 16, 1846-1848 (2004).
    [CrossRef]
  4. Lixia Li, Gregory P. Nordin, Jennifer M. English, Jianhua Jiang, "Small-area bends and beamsplitters for low-index-contrast waveguides," Opt. Express 11, 282-290 (2003).
    [CrossRef] [PubMed]
  5. Kazuhiko Ogusu, �??Transmission Characteristics of Optical Waveguide Corners,�?? Opt. Commum. 55, 149-153 (1985).
    [CrossRef]
  6. Regis Orobtchouk, Suzanne Laval, Daniel Pascal, and Alain Koster, �??Analysis of Integrated Optical Waveguide Mirrors,�?? J. Lightwave Technol. 15, 815-820 (1997).
    [CrossRef]
  7. L. Faustini, C. Coriasso, A. Stano, C. Cacciatore, and D. Campi, �??Loss Analysis and Interference Effect in Semiconductor Integrated Waveguide Turning Mirrors,�?? Photon. Technol. Lett. 8, 1355-1357 (1996).
    [CrossRef]
  8. John E. Johnson, C. L. Tang, �??Precise Determination of Turning Mirror Loss Using GaAs/AlGaAs Lasers with up to Ten 90° Intracavity Turning Mirrors,�?? Photon. Techn. Lett. 4, 24-26 (1992).
    [CrossRef]
  9. P. D. Swanson, D. B. Shire, C. L. Tang, M. A. Parker, J. S. Kimmet, and R. J. Michalak, �??Electron-Cyclotron Resonance Etching of Mirrors for Ridge-Guided Lasers,�?? Photon. Techn. Lett. 7, 605-607 (1995).
    [CrossRef]
  10. Y. Z. Tang, W. H. Wang, T. Li, and Y. L. Wang, �??Integrated Waveguide Turning Mirror in Silicon-on-Insulator,�?? Phot. Techn. Lett. 14, 68-70 (2002).
    [CrossRef]
  11. Smith, Jr., D.W.; Chen, S.; Kumar, S.; Ballato, J.; Shah, H.; Topping, C.; Foulger, �??Perfluorocyclobutyl Copolymers for Microphotonics,�?? S. Adv. Mater. 14, 1585 (2002).
    [CrossRef]
  12. Smith, Jr., D.W.; Hoeglund, A.B.; Shah, H.V.; Radler, M.J.; Langhoff, C.A., �??Perfluorocyclobutane Polymers for Optical Fibers and Dielectric Waveguides,�?? in Optical Polymers, Harmon, J.; Ed., ACS Symp. Ser. 795, Ch. 4, pp. 49-62 (2001).
    [CrossRef]
  13. John Ballato, Dennis W. Smith Jr, S. H. Foulger, �??Optical Properties of Perfluorocyclobutyl (PFCB) Polymers,�?? J. Opt. Soc. Am. B 20 1838 (2003).
    [CrossRef]

IEEE Phot. Technol. Lett. (1)

Seunghyun Kim, Gregory P. Nordin., Jianhua Jiang, Jingbo Cai, "High Efficiency 90° Silica Waveguide Bend Using an Air Hole Photonic Crystal Region," IEEE Phot. Technol. Lett. 16, 1846-1848 (2004).
[CrossRef]

IEEE Proc. Optoelectron. (1)

L.H. Spiekman, Y. S. O., E.G. Metaal, F.H. Groen, P. Demeester, M.K. Smit, "Ultrasmall waveguide bends: the corner mirrors of the future?" IEEE Proc. Optoelectron. 142, 61-65 (1995).
[CrossRef]

J. Lightwave Technol. (2)

Milos Popovic, K. W., Shoji Akiyama, Hermann A. Haus, Jurgen Michel, "Air Trenches for Sharp Silica Waveguide Bends," J. Lightwave Technol. 20, 1762-1772 (2002).
[CrossRef]

Regis Orobtchouk, Suzanne Laval, Daniel Pascal, and Alain Koster, �??Analysis of Integrated Optical Waveguide Mirrors,�?? J. Lightwave Technol. 15, 815-820 (1997).
[CrossRef]

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

Opt. Commum. (1)

Kazuhiko Ogusu, �??Transmission Characteristics of Optical Waveguide Corners,�?? Opt. Commum. 55, 149-153 (1985).
[CrossRef]

Opt. Express (1)

Optical Polymers (1)

Smith, Jr., D.W.; Hoeglund, A.B.; Shah, H.V.; Radler, M.J.; Langhoff, C.A., �??Perfluorocyclobutane Polymers for Optical Fibers and Dielectric Waveguides,�?? in Optical Polymers, Harmon, J.; Ed., ACS Symp. Ser. 795, Ch. 4, pp. 49-62 (2001).
[CrossRef]

Phot. Techn. Lett. (1)

Y. Z. Tang, W. H. Wang, T. Li, and Y. L. Wang, �??Integrated Waveguide Turning Mirror in Silicon-on-Insulator,�?? Phot. Techn. Lett. 14, 68-70 (2002).
[CrossRef]

Photon. Techn. Lett. (2)

John E. Johnson, C. L. Tang, �??Precise Determination of Turning Mirror Loss Using GaAs/AlGaAs Lasers with up to Ten 90° Intracavity Turning Mirrors,�?? Photon. Techn. Lett. 4, 24-26 (1992).
[CrossRef]

P. D. Swanson, D. B. Shire, C. L. Tang, M. A. Parker, J. S. Kimmet, and R. J. Michalak, �??Electron-Cyclotron Resonance Etching of Mirrors for Ridge-Guided Lasers,�?? Photon. Techn. Lett. 7, 605-607 (1995).
[CrossRef]

Photon. Technol. Lett. (1)

L. Faustini, C. Coriasso, A. Stano, C. Cacciatore, and D. Campi, �??Loss Analysis and Interference Effect in Semiconductor Integrated Waveguide Turning Mirrors,�?? Photon. Technol. Lett. 8, 1355-1357 (1996).
[CrossRef]

S. Adv. Mater. (1)

Smith, Jr., D.W.; Chen, S.; Kumar, S.; Ballato, J.; Shah, H.; Topping, C.; Foulger, �??Perfluorocyclobutyl Copolymers for Microphotonics,�?? S. Adv. Mater. 14, 1585 (2002).
[CrossRef]

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Figures (11)

Fig. 1.
Fig. 1.

Top view of SAIB structure for a 45° waveguide bend showing the air interface placement and choice of reference point for design.

Fig. 2.
Fig. 2.

Magnitude squared time averaged (a) magnetic field plot (TE polarization) and (b) electric field plot (TM polarization) at λ=1.55µm.

Fig. 3.
Fig. 3.

(a) Bend efficiency as a function of the position of the air interface relative to the O position. The designed position of the SAIB is zp=-0.2µm. Note that the vertical axis starts at a bend efficiency of 0.5.

Fig. 4.
Fig. 4.

(a) Cross-section SEM image showing the typical etch undercut (1.1µm as depicted by the cursor width) for an air trench.

Fig. 5.
Fig. 5.

Microscope image taken with a DIC filter through a 50x objective focused at the waveguide plane of SAIBs in good alignment.

Fig. 6.
Fig. 6.

SEM image of finished air trench bend. The rounded edges are introduced to reduce stress. The dotted line depicts the waveguide core location.

Fig. 7.
Fig. 7.

SEM image of a typical sidewall for the deep anisotropic air trench etch.

Fig. 8.
Fig. 8.

SEM image of a typical air trench sidewall.

Fig. 9.
Fig. 9.

(a) Output power as a function of moving the output fiber away from the waveguide. (b) Standard deviation for measured output power in ten different measurements.

Fig. 10.
Fig. 10.

Measurement data for a waveguide group that shows a bend efficiency of 93.4% with error bars indicating the variability introduced by measurement uncertainty. This waveguide group has an undercut compensation of 1.1µm.

Fig. 11.
Fig. 11.

Simulation and measurement data as a function of SAIB interface misplacement. The horizontal axis is the actual offset introduced into the SAIB mask to compensate for misalignment.

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