Abstract

We present a full description of the design and fabrication of a compact laterally tapered spotsize converter (SSC) that provides both low-loss coupling and large fabrication tolerances. The SSC is based on a laterally tapered waveguide with a narrow core width that can be fabricated simply by using the usual fabrication process. We discuss the design concept of the SSC in detail and provide a simple design procedure with which to obtain the optimum SSC design parameters. We also investigate the fiber misalignment tolerance and mode field diameter of the SSC and confirm that it is suitable for integration with large-scale optical devices. Furthermore, we examine the performance of the SSC for higher refractive index difference (Delta) of 2.0% and 2.5% with a smaller bending radius. We fabricated the 2-mm-long SSC using 1.5%-, 2.0%-, and 2.5%-Delta silica-based planar lightwave circuits. This enabled us to reduce the single-mode fiber coupling loss to 0.4 dB at a single waveguide junction with a low polarization-dependent loss of 0.05 dB regardless of the Delta; values, while providing a core width fabrication tolerance of ±0.3 µm and an endface position tolerance of ±0.2 mm.

© 2004 IEEE

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  1. A. Himeno, K. Kato and T. Miya, "Silica-based planar lightwave circuits", IEEE J. Select. Topics Quantum Electron., vol. 4, pp. 913-924, Nov.-Dec. 1998.
  2. Y. Hibino, "High contrast waveguide devices", in Proc. OFC , 2001, pp. WB1-1-WB1-3.
  3. Y. Hida, Y. Hibino, T. Kitoh, Y. Inoue, M. Itoh, T. Shibata, A. Sugita and A. Himeno, "400-channel arrayed-waveguide grating with 25 GHz spacing using 1.5%-Delta waveguides on 6-inch Si wafer", Electron. Lett., vol. 37, pp. 576-577, 2001.
  4. I. Moerman, P. P. Van Daele and P. M. Demeester, "A review of fabrication technologies for the monolithic integration of tapers with III-V semiconductor devices", IEEE J. Select. Topics Quantum Electron., vol. 3, pp. 1308-1320, 1997.
  5. M. Ishii, Y. Hibino, Y. Hida, A. Kaneko, M. Itoh, T. Goh, A. Sugita, T. Saida, A. Himeno and Y. Ohmori, "Low-loss and compact silica-based 16 channel arrayed-waveguide grating multiplexer module with higher index difference", in Proc. ECOC, 2000, pp. 212- 213.
  6. R. Zengerle, O. Leminger, W. Weiershausen, K. Faltin and B. Hübner, "Laterally tapered InP-InGaAsP waveguides for low-loss chip-to-fiber butt coupling: A comparison of different configurations", IEEE Photon. Technol. Lett., vol. 7, pp. 532-534, May 1995.
  7. M. Ishii, A. Takagi, Y. Hida, M. Itoh, S. Kamei, T. Saida, Y. Hibino, A. Sugita and T. Kitagawa, "Low-loss fiber-pigtailed 256 channel arrayed-waveguide grating multiplexer using cascaded laterally-tapered waveguides", Electron. Lett., vol. 37, pp. 1401-1402, 2001.
  8. O. Mitomi, K. Kasaya, Y. Tohmori, Y. Suzaki, H. Fukano, Y. Sakai, M. Okamoto and S. Matsumoto, "Optical spot-size converters for low-loss coupling between fibers and optoelectronic semiconductor devices", J. Lightwave Technol., vol. 14, pp. 1714-1720, July 1996.
  9. T. Bakke, C. T. Sullivan and S. D. Mukherjee, "Vertically tapered core polymeric optical spot-size transformer", Electron. Lett., vol. 37, pp. 1475-1476, 2001.
  10. Z. Weissman and A. Hardy, "Modes of periodically segmented waveguides", J. Lightwave Technol., vol. 11, pp. 1831-1838, Nov. 1993 .
  11. M. M. Spühler, B. J. Offrein, G.-L. Bona, R. Germann, I. Massarek and D. Erni, "A very short planar silica spot-size converter using a nonperiodic segmented waveguide", J. Lightwave Technol., vol. 16, pp. 1680-1685, Sept. 1998 .
  12. N. Yamaguchi, Y. Kokubun and K. Sato, "Low-loss spot-size transformer by dual tapered waveguides (DTW-SST)", J. Lightwave Technol., vol. 8, pp. 587-594, Apr. 1990.
  13. H. Yanagawa, T. Shimizu, S. Nakamura and I. Ohyama, "Index-and-dimensional taper and its application to photonic devices", J. Lightwave Technol., vol. 10, pp. 587-592, May 1992.
  14. M. Itoh, T. Saida, Y. Hida, M. Ishii, Y. Inoue, Y. Hibino and A. Sugita, "Large reduction of singlemode-fiber coupling loss in 1.5% Delta planar lightwave circuits using spot-size converters", Electron. Lett., vol. 38, pp. 72-74, 2002.
  15. M. Itoh, T. Saida, Y. Hida, M. Ishii, Y. Inoue, Y. Hibino and A. Sugita, "Low-loss 1.5% Delta arrayed waveguide grating with spot-size converters", in Proc. ECOC, 2001, pp. 8-9.
  16. K. Kasaya, O. Mitomi, M. Naganuma, Y. Kondo and Y. Noguchi, "A simple laterally tapered waveguide for low-loss coupling to single-mode fibers", IEEE Photon. Technol. Lett., vol. 5, pp. 345-347, Mar. 1993.
  17. T. Mizuno, T. Kitoh, T. Saida, Y. Inoue, M. Itoh, T. Shibata, Y. Hibino and Y. Hida, "Low-loss 1.5%-Delta arrayed waveguide grating with narrow laterally tapered spotsize converter", Electron. Lett., vol. 37, pp. 1452-1454, 2001.
  18. T. Mizuno, T. Kitoh, M. Ishii, Y. Inoue, T. Saida, M. Itoh, T. Shibata and Y. Hibino, "Compact and low-loss arrayed waveguide grating module with tolerance-relaxed spot-size converter", IEEE Photon. Technol. Lett., vol. 15, pp. 239-241, Feb. 2003.
  19. J. C. Chen and S. Jüngling, "Computation of higher-order waveguide modes by imaginary-distance beam propagation method", Opt. Quantum Electron., vol. 26, pp. S199-S205, 1994.
  20. K. Okamoto, Fundamentals of Optical Waveguides, New York: Academic, 2000, ch. 9.
  21. A. Sugita, A. Kaneko, K. Okamoto, M. Itoh, A. Himeno and Y. Ohmori, "Very low insertion loss arrayed-waveguide grating with vertically tapered waveguides", IEEE Photon. Technol. Lett., vol. 12, pp. 1180-1182, Sept. 2000.
  22. R. Kasahara, M. Itoh, Y. Hida, T. Saida, Y. Inoue and Y. Hibino, "Birefringence compensated silica-based waveguide with undercladding ridge", Electron. Lett., vol. 38, pp. 1178-1179, 2002.
  23. M. Ishii, Y. Hibino, F. Hanawa, H. Nakagome and K. Kato, "Packaging and environmental stability of thermally controlled arrayed-waveguide grating multiplexer module with thermoelectric device", J. Lightwave Technol., vol. 16, pp. 258-264, Feb. 1998 .

J. Lightwave Technol.

Z. Weissman and A. Hardy, "Modes of periodically segmented waveguides", J. Lightwave Technol., vol. 11, pp. 1831-1838, Nov. 1993 .

N. Yamaguchi, Y. Kokubun and K. Sato, "Low-loss spot-size transformer by dual tapered waveguides (DTW-SST)", J. Lightwave Technol., vol. 8, pp. 587-594, Apr. 1990.

H. Yanagawa, T. Shimizu, S. Nakamura and I. Ohyama, "Index-and-dimensional taper and its application to photonic devices", J. Lightwave Technol., vol. 10, pp. 587-592, May 1992.

O. Mitomi, K. Kasaya, Y. Tohmori, Y. Suzaki, H. Fukano, Y. Sakai, M. Okamoto and S. Matsumoto, "Optical spot-size converters for low-loss coupling between fibers and optoelectronic semiconductor devices", J. Lightwave Technol., vol. 14, pp. 1714-1720, July 1996.

M. Ishii, Y. Hibino, F. Hanawa, H. Nakagome and K. Kato, "Packaging and environmental stability of thermally controlled arrayed-waveguide grating multiplexer module with thermoelectric device", J. Lightwave Technol., vol. 16, pp. 258-264, Feb. 1998 .

M. M. Spühler, B. J. Offrein, G.-L. Bona, R. Germann, I. Massarek and D. Erni, "A very short planar silica spot-size converter using a nonperiodic segmented waveguide", J. Lightwave Technol., vol. 16, pp. 1680-1685, Sept. 1998 .

Other

T. Bakke, C. T. Sullivan and S. D. Mukherjee, "Vertically tapered core polymeric optical spot-size transformer", Electron. Lett., vol. 37, pp. 1475-1476, 2001.

A. Himeno, K. Kato and T. Miya, "Silica-based planar lightwave circuits", IEEE J. Select. Topics Quantum Electron., vol. 4, pp. 913-924, Nov.-Dec. 1998.

Y. Hibino, "High contrast waveguide devices", in Proc. OFC , 2001, pp. WB1-1-WB1-3.

Y. Hida, Y. Hibino, T. Kitoh, Y. Inoue, M. Itoh, T. Shibata, A. Sugita and A. Himeno, "400-channel arrayed-waveguide grating with 25 GHz spacing using 1.5%-Delta waveguides on 6-inch Si wafer", Electron. Lett., vol. 37, pp. 576-577, 2001.

I. Moerman, P. P. Van Daele and P. M. Demeester, "A review of fabrication technologies for the monolithic integration of tapers with III-V semiconductor devices", IEEE J. Select. Topics Quantum Electron., vol. 3, pp. 1308-1320, 1997.

M. Ishii, Y. Hibino, Y. Hida, A. Kaneko, M. Itoh, T. Goh, A. Sugita, T. Saida, A. Himeno and Y. Ohmori, "Low-loss and compact silica-based 16 channel arrayed-waveguide grating multiplexer module with higher index difference", in Proc. ECOC, 2000, pp. 212- 213.

R. Zengerle, O. Leminger, W. Weiershausen, K. Faltin and B. Hübner, "Laterally tapered InP-InGaAsP waveguides for low-loss chip-to-fiber butt coupling: A comparison of different configurations", IEEE Photon. Technol. Lett., vol. 7, pp. 532-534, May 1995.

M. Ishii, A. Takagi, Y. Hida, M. Itoh, S. Kamei, T. Saida, Y. Hibino, A. Sugita and T. Kitagawa, "Low-loss fiber-pigtailed 256 channel arrayed-waveguide grating multiplexer using cascaded laterally-tapered waveguides", Electron. Lett., vol. 37, pp. 1401-1402, 2001.

M. Itoh, T. Saida, Y. Hida, M. Ishii, Y. Inoue, Y. Hibino and A. Sugita, "Large reduction of singlemode-fiber coupling loss in 1.5% Delta planar lightwave circuits using spot-size converters", Electron. Lett., vol. 38, pp. 72-74, 2002.

M. Itoh, T. Saida, Y. Hida, M. Ishii, Y. Inoue, Y. Hibino and A. Sugita, "Low-loss 1.5% Delta arrayed waveguide grating with spot-size converters", in Proc. ECOC, 2001, pp. 8-9.

K. Kasaya, O. Mitomi, M. Naganuma, Y. Kondo and Y. Noguchi, "A simple laterally tapered waveguide for low-loss coupling to single-mode fibers", IEEE Photon. Technol. Lett., vol. 5, pp. 345-347, Mar. 1993.

T. Mizuno, T. Kitoh, T. Saida, Y. Inoue, M. Itoh, T. Shibata, Y. Hibino and Y. Hida, "Low-loss 1.5%-Delta arrayed waveguide grating with narrow laterally tapered spotsize converter", Electron. Lett., vol. 37, pp. 1452-1454, 2001.

T. Mizuno, T. Kitoh, M. Ishii, Y. Inoue, T. Saida, M. Itoh, T. Shibata and Y. Hibino, "Compact and low-loss arrayed waveguide grating module with tolerance-relaxed spot-size converter", IEEE Photon. Technol. Lett., vol. 15, pp. 239-241, Feb. 2003.

J. C. Chen and S. Jüngling, "Computation of higher-order waveguide modes by imaginary-distance beam propagation method", Opt. Quantum Electron., vol. 26, pp. S199-S205, 1994.

K. Okamoto, Fundamentals of Optical Waveguides, New York: Academic, 2000, ch. 9.

A. Sugita, A. Kaneko, K. Okamoto, M. Itoh, A. Himeno and Y. Ohmori, "Very low insertion loss arrayed-waveguide grating with vertically tapered waveguides", IEEE Photon. Technol. Lett., vol. 12, pp. 1180-1182, Sept. 2000.

R. Kasahara, M. Itoh, Y. Hida, T. Saida, Y. Inoue and Y. Hibino, "Birefringence compensated silica-based waveguide with undercladding ridge", Electron. Lett., vol. 38, pp. 1178-1179, 2002.

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