Etched Waveguide Grating Variable 1 2 Splitter/Combiner and Waveguide Coupler
ABSTRACT We propose and test a silicon waveguide grating which serves dual functions: as a 1 times 2 variable integrated beam splitter/combiner and as an out-of plane diffractive element for coupling light between a single-mode optical fiber and a 500-nm-wide silicon-on-insulator waveguide. An integrated Mach-Zehnder interferometer made with this novel functional element had over 20-dB extinction ratio. The splitting ratio can be tuned by changing the launch position of the optical fiber. The grating coupler had over 36% coupling efficiency and a 1-dB spectral bandwidth of 37 nm.
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ABSTRACT: We review our recent work on chirped waveguide gratings for efficient coupling between standard single mode optical fibers and silicon photonic wire waveguides. The use of a linear chirp in grating period reduces the second order Bragg reflection from the waveguide gratings and increases the coupling efficiency for perfectly vertical optical fibers. Measurement results obtained from devices fabricated using deep UV lithography yielded coupling efficiencies of over 34%. Techniques to further improve the coupling efficiency will be discussed. The use of chirped waveguide gratings for low cost photonic packaging and the application of waveguide gratings for splitting/combining light will also be presented.01/2009;
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ABSTRACT: Simulation and experimental results of grating couplers composed of arrays of nanoholes are presented. The use of an array of holes instead of a conventional waveguide grating provides an additional degree of freedom in the design of the coupler, thus enabling fabrication using the same photolithography mask and etching process as used for the silicon-on-insulator (SOI) waveguides. A grating coupler with coupling efficiency as high as 34% for coupling between the TE mode of the silicon nanophotonic wire waveguide and a single-mode optical fiber and with 3-dB bandwidth of 40 nm was fabricated. A theoretical model is presented, and 3-D finite-difference time-domain simulations are used to optimize the coupler design.IEEE Photonics Journal 10/2009; · 2.36 Impact Factor