Ultracompact tapers for light coupling into two-dimensional slab photonic-crystal waveguides in the slow light regime

Optical coupling from a strip waveguide to a two-dimensional photonic crystal (PC) slab waveguide in the slow light regime is investigated. Group-velocity mismatch between optical modes is responsible for large coupling loss. Typical devices based on a W1 PC waveguide, with strip input and output waveguides on each side, are studied using finite-difference time-domain and plane-wave expansion calculations. Compact tapers based on PC lattice parameter tuning are proposed to reduce the coupling loss. At 1.6 μm, for an optical mode with group velocity v g /c=0.054, the transmission can be enhanced from 18% without tapers to 95% with a 3.4-μm-long taper on each side of the PC.

[1]  Yurii A Vlasov,et al.  Coupling into the slow light mode in slab-type photonic crystal waveguides. , 2006, Optics letters.

[2]  Tony Reichhardt,et al.  Have NASA's scientists been the victims of excessive expectations? , 1999, Nature.

[3]  Steven G. Johnson,et al.  Block-iterative frequency-domain methods for Maxwell's equations in a planewave basis. , 2001, Optics express.

[4]  Y. Vlasov,et al.  Losses in single-mode silicon-on-insulator strip waveguides and bends. , 2004, Optics express.

[5]  Steven G. Johnson,et al.  Slow-light, band-edge waveguides for tunable time delays. , 2005, Optics express.

[6]  Thomas F. Krauss.  Slow light in photonic crystal waveguides , 2007 .

[7]  S. Selleri,et al.  Design of photonic-crystal and wire waveguide interface , 2005, Journal of Lightwave Technology.

[8]  B. Momeni,et al.  Adiabatic matching stage for coupling of light to extended Bloch modes of photonic crystals , 2005 .

[9]  L C Kimerling,et al.  Fabrication of ultralow-loss Si/SiO(2) waveguides by roughness reduction. , 2001, Optics letters.

[10]  M. Notomi,et al.  Extremely large group-velocity dispersion of line-defect waveguides in photonic crystal slabs. , 2001, Physical review letters.

[11]  A. Scherer,et al.  Coupled-resonator optical waveguide: a proposal and analysis. , 1999, Optics letters.

[12]  R. Osgood,et al.  A study of high-index-contrast 90 degree waveguide bend structures. , 2001, Optics express.

[13]  P. Dumon,et al.  Basic structures for photonic integrated circuits in Silicon-on-insulator. , 2004, Optics express.

[14]  T. Baba,et al.  Light localizations in photonic crystal line defect waveguides , 2004, IEEE Journal of Selected Topics in Quantum Electronics.

[15]  Jacob Fage-Pedersen,et al.  Photonic crystal waveguides with semi-slow light and tailored dispersion properties. , 2006, Optics express.

[16]  Wan Kuang,et al.  Dispersion characteristics of photonic crystal coupled resonator optical waveguides. , 2003, Optics express.

[17]  Rana Biswas,et al.  Impedance of photonic crystals and photonic crystal waveguides , 2004 .

[18]  J. D. Joannopoulos,et al.  Enhancement of nonlinear effects using photonic crystals , 2004, Nature materials.

[19]  Pablo Sanchis,et al.  Mode matching technique for highly efficient coupling between dielectric waveguides and planar photonic crystal circuits. , 2002, Optics express.

[20]  Ali Adibi,et al.  Investigation of physical mechanisms in coupling photonic crystal waveguiding structures. , 2004, Optics express.

[21]  Mario Martinelli,et al.  Optical Slow Wave Structures , 2003 .

[22]  Steven G. Johnson,et al.  Photonic-crystal slow-light enhancement of nonlinear phase sensitivity , 2002 .

[23]  A. Yariv,et al.  Coupled resonator optical waveguides , 2002 .

[24]  Wei Jiang,et al.  80-micron interaction length silicon photonic crystal waveguide modulator , 2005 .

[25]  Toshihiko Baba,et al.  Dispersion-controlled optical group delay device by chirped photonic crystal waveguides , 2004 .