Chinese Optics Letters, Vol. 5, Issue 10, 577 (2007)
Subwavelength-diameter silica wire for light in-coupling to silicon-based waveguide
Ziyang Zhang1, Min Qiu1,*, Ulf Andersson2, and Limin Tong3
- 1Department of Microelectronics and Applied Physics, Royal Institute of Technology (KTH), Electrum 229, 164 40 Kista, Sweden
- 2Center for Parallel Computers, Royal Institute of Technology (KTH), 100 44 Stockholm, Sweden
- 3Department of Optical Engineering, Zhejiang University, Hangzhou 310027
Coupling between subwavelength-diameter silica wires and silicon-based waveguides is studied using the parallel three-dimensional (3D) finite-different time-domain method. Conventional butt-coupling to a silica-substrated silicon wire waveguide gives above 40% transmission at the wavelength range from 1300 to 1750 nm with good robustness against axial misalignments. Slow light can be generated by counter-directional coupling between a silica wire and a two-dimensional (2D) silicon photonic crystal slab waveguide. Through dispersion-band engineering, 82% transmission is achieved over a coupling distance of 50 lattice constants. The group velocity is estimated as 1/35 of the light speed in vacuum.