Two dimensional silicon waveguide chirped grating couplers for vertical optical fibers

• Published in: Optics communications Vol. 283; no. 10; pp. 2146 - 2149
• Main Authors: Chen, Xia, Li, Chao, Tsang, Hon Ki
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.05.2010; Elsevier
• Subjects: Coupler; Couplers; Diffraction gratings; Etching; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Gratings (spectra); Integrated optics; Nanostructure; Optical elements, devices, and systems; Optical fibers; Optical waveguides and coupleurs; Optics; Physics; Silicon; Silicon-on-insulator; Wave optics; Wave propagation, transmission and absorption; Waveguide grating; Waveguides; Integrated optics; Coupler; Waveguide grating; Silicon-on-insulator; Optical fibers; Nanophotonics; Electromagnetic wave propagation; Silicon; Optical waveguides
• DOI: 10.1016/j.optcom.2010.01.059
• ISSN: 0030-4018

Shallow etched two dimensional gratings for coupling light between silicon-on-insulator nanophotonic waveguides and vertical optical fibers were designed and experimentally characterized. We show that the large second order back reflection could be suppressed effectively by applying a linear chirp in the grating period for two dimensional grating couplers. The total coupling efficiency from an optical fiber to two orthogonal silicon waveguides is independent of the input polarization. An almost linear relationship between the average effective index of the grating region and the fill factor for 1D grating is obtained and verified. We also show that the average effective index for the two dimensional grating is similar to the one dimensional grating with the same fill factor in the light propagation direction, when the fill factor of the etched holes was larger than 0.5.