Abstract

A simple light-beam spot-size converter (SSC) using a microscale graded-index (GRIN)-slab tip with a hemicylindrical endface for efficient coupling between a single-mode fiber and a fine-core waveguide is reported. Numerical examples based on the finite-difference time-domain (FDTD) method have shown that the tip made of a -SiOx:H is capable of coupling a narrow field, 0.5 µm in radius at a wavelength of 1.55 µm, to a 5.3-µm radius standard single-mode fiber with a coupling loss as low as 0.07 dB. A micro GRIN slab with an index difference of as much as 34% was successfully fabricated. It has been confirmed experimentally that a GRIN slab with a hemicylindrical endface of 27-µm radii, a thickness of 33 µm, and a length of 35 µm, is capable of converting a spot radius of a single-mode fiber (5.3 µm) into a spot radius of 1.1 µm at a wavelength of 1.55 µm.

© 2005 IEEE

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  1. B. E. Little, J. S. Foresi, G. Steinmeyer, E. R. Thoen, S. T. Chu, H. A. Haus, E. P. Ippen, L. C. Kimerling and W. Greene, "Ultra-compact Si-SiO2 microring resonator optical channel dropping filters", IEEE Photon. Technol. Lett., vol. 10, no. 4, pp. 549-551, Apr. 1998.
  2. K. K. Lee, D. R. Lim, H. C. Luan, A. Agarwal, J. Foresi and L. C. Kimerling, "Effect of size and roughness on light transmission in a Si/SiO2 waveguide: Experiments and model", Appl. Phys. Lett., vol. 77, no. 11, pp. 1617-1619, Sep. 2000.
  3. A. Sakai, G. Hara and T. Baba, "Propagation characteristics of ultrahigh-Delta optical waveguide on silicon-on-insulator substrate", Jpn. J. Appl. Phys., vol. 40, no. 4B, pp. L383-L385, Apr. 2001.
  4. H. A. Haus, "High density optical integration", in Tutorial, IEEE Lasers and Electro-Optics Society, Glasgow, U.K.,Nov. 2002, pp. 389-390.
  5. T. Tsuchizawa, T. Watanabe, E. Tamechika, T. Shiji, K. Yamada, J. Takahashi, S. Uchiyama, S. Itabashi and H. Morita, "Fabrication and evaluation of submicron-square Si wire waveguides with spot size converters", in Tech. Dig., IEEE Lasers and Electro-Optics Society, Glasgow, U.K.,Nov. 2002,Paper TuU2,. pp. 287-288.
  6. T. Shoji, T. Tsuchizawa, T. Watanabe, K. Yamada and H. Morita, "Spot-size converter for low-loss coupling between 0.3-µm -square Si wire waveguides and single-mode fibers", in Tech. Dig., IEEE Lasers and Electro-Optics Society, Glasgow, U.K.,Nov. 2002,Paper TuU3,. pp. 289-290.
  7. B. Luyssaert, "2-D simulation of various compact spot-size converters", in Int. Workshop Photonic and Electromagnetic Crystal Structures, Los Angeles, CA, Oct. 2002, p. 62.
  8. D. Taillaert, W. Bogaerts and R. Baets, "Out-of-plane fiber coupler for coupling to high-index-contrast waveguides", in Int. Workshop Photonic and Electromagnetic Crystal Structures, Los Angeles, CA, Oct. 2002, p. 155.
  9. A. M. Agarwal, L. C. Kimerling, H. A. Haus, K. Wada, S. G. Johnson, C. Manoulatou, J. Michel and V. T. Nguyen, "Vertically and laterally confined 3D optical coupler", U.S. Patent Appl. Pub., No. U.S. 2003/0035633A1, Feb. 20, 2003.
  10. N. Yamaguchi, Y. Kokubun and K. Sato, "Low-loss spot-size transformer by dual tapered waveguides (DTW-SST)", J. Lightw. Technol., vol. 18, no. 4, pp. 587-594, Apr. 1990.
  11. J. Nakano, A. Ogura and K. Shiraishi, "A new scheme of the thick-film graded-index micro slab lens", presented at the Nat. Convention Record, IEICE, Tokyo, Japan,Paper C-3-133, Mar. 2002.
  12. K. Shiraishi, C. S. Tsai, H. Yoda, T. Ito and I. Tomita, "A novel spot-size converter using cylindrical micro GRIN slab tip", presented at the 9th Microoptics Conf., Tokyo, Japan,Paper H42, Oct. 2003.
  13. K. Shiraishi, C. S. Tsai, H. Yoda and K. Minagawa, "A micro GRIN-slab tip for integrated coupling between superfine-core waveguides and single-mode fibers", presented at the 5th Pacific Rim Conf. Lasers and Electro-Optics, Taipei, Taiwan, R.O.C.,Paper W2I-(8)-7, Dec. 2003.
  14. K. Shiraishi, A. Ogura and K. Matsuura, "Spotsize contraction in standard single-mode fibers by use of a GI-fiber tip with a high focusing parameter", IEEE Photon. Technol. Lett., vol. 10, no. 12, pp. 1757-1759, Dec. 1998.
  15. A. Ogura, K. Shiraishi and H. Kato, "Experimental performance of silica GIO fibers with a highly elliptic core", IEEE Photon. Technol. Lett., vol. 13, no. 6, pp. 594-596, Jun. 2001.
  16. K. Muro and K. Shiraishi, "Poly-Si/SiO2 laminated walk-off polarizer having a beam-splitting angle of more than 20°", J. Lightw. Technol., vol. 16, no. 1, pp. 127-133, Jan. 1998.

Other (16)

B. E. Little, J. S. Foresi, G. Steinmeyer, E. R. Thoen, S. T. Chu, H. A. Haus, E. P. Ippen, L. C. Kimerling and W. Greene, "Ultra-compact Si-SiO2 microring resonator optical channel dropping filters", IEEE Photon. Technol. Lett., vol. 10, no. 4, pp. 549-551, Apr. 1998.

K. K. Lee, D. R. Lim, H. C. Luan, A. Agarwal, J. Foresi and L. C. Kimerling, "Effect of size and roughness on light transmission in a Si/SiO2 waveguide: Experiments and model", Appl. Phys. Lett., vol. 77, no. 11, pp. 1617-1619, Sep. 2000.

A. Sakai, G. Hara and T. Baba, "Propagation characteristics of ultrahigh-Delta optical waveguide on silicon-on-insulator substrate", Jpn. J. Appl. Phys., vol. 40, no. 4B, pp. L383-L385, Apr. 2001.

H. A. Haus, "High density optical integration", in Tutorial, IEEE Lasers and Electro-Optics Society, Glasgow, U.K.,Nov. 2002, pp. 389-390.

T. Tsuchizawa, T. Watanabe, E. Tamechika, T. Shiji, K. Yamada, J. Takahashi, S. Uchiyama, S. Itabashi and H. Morita, "Fabrication and evaluation of submicron-square Si wire waveguides with spot size converters", in Tech. Dig., IEEE Lasers and Electro-Optics Society, Glasgow, U.K.,Nov. 2002,Paper TuU2,. pp. 287-288.

T. Shoji, T. Tsuchizawa, T. Watanabe, K. Yamada and H. Morita, "Spot-size converter for low-loss coupling between 0.3-µm -square Si wire waveguides and single-mode fibers", in Tech. Dig., IEEE Lasers and Electro-Optics Society, Glasgow, U.K.,Nov. 2002,Paper TuU3,. pp. 289-290.

B. Luyssaert, "2-D simulation of various compact spot-size converters", in Int. Workshop Photonic and Electromagnetic Crystal Structures, Los Angeles, CA, Oct. 2002, p. 62.

D. Taillaert, W. Bogaerts and R. Baets, "Out-of-plane fiber coupler for coupling to high-index-contrast waveguides", in Int. Workshop Photonic and Electromagnetic Crystal Structures, Los Angeles, CA, Oct. 2002, p. 155.

A. M. Agarwal, L. C. Kimerling, H. A. Haus, K. Wada, S. G. Johnson, C. Manoulatou, J. Michel and V. T. Nguyen, "Vertically and laterally confined 3D optical coupler", U.S. Patent Appl. Pub., No. U.S. 2003/0035633A1, Feb. 20, 2003.

N. Yamaguchi, Y. Kokubun and K. Sato, "Low-loss spot-size transformer by dual tapered waveguides (DTW-SST)", J. Lightw. Technol., vol. 18, no. 4, pp. 587-594, Apr. 1990.

J. Nakano, A. Ogura and K. Shiraishi, "A new scheme of the thick-film graded-index micro slab lens", presented at the Nat. Convention Record, IEICE, Tokyo, Japan,Paper C-3-133, Mar. 2002.

K. Shiraishi, C. S. Tsai, H. Yoda, T. Ito and I. Tomita, "A novel spot-size converter using cylindrical micro GRIN slab tip", presented at the 9th Microoptics Conf., Tokyo, Japan,Paper H42, Oct. 2003.

K. Shiraishi, C. S. Tsai, H. Yoda and K. Minagawa, "A micro GRIN-slab tip for integrated coupling between superfine-core waveguides and single-mode fibers", presented at the 5th Pacific Rim Conf. Lasers and Electro-Optics, Taipei, Taiwan, R.O.C.,Paper W2I-(8)-7, Dec. 2003.

K. Shiraishi, A. Ogura and K. Matsuura, "Spotsize contraction in standard single-mode fibers by use of a GI-fiber tip with a high focusing parameter", IEEE Photon. Technol. Lett., vol. 10, no. 12, pp. 1757-1759, Dec. 1998.

A. Ogura, K. Shiraishi and H. Kato, "Experimental performance of silica GIO fibers with a highly elliptic core", IEEE Photon. Technol. Lett., vol. 13, no. 6, pp. 594-596, Jun. 2001.

K. Muro and K. Shiraishi, "Poly-Si/SiO2 laminated walk-off polarizer having a beam-splitting angle of more than 20°", J. Lightw. Technol., vol. 16, no. 1, pp. 127-133, Jan. 1998.

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