Multichannel high-bandwidth coupling of ultradense silicon photonic waveguide array to standard-pitch fiber array

Fuad E. Doany, Benjamin G. Lee, Solomon Assefa, William M.J. Green, Min Yang, Clint L. Schow, Christopher V. Jahnes, Sheng Zhang, Jonathan Singer, Victor I. Kopp, Jeffrey A. Kash, Yurii A. Vlasov

Research output: Contribution to journalArticlepeer-review


A multichannel tapered coupler interfacing standard 250-μm-pitch low-numerical-aperture (NA) polarization-maintaining fiber arrays with ultradense 20-μm-pitch high-NA silicon waveguides is designed and fabricated. The coupler is based on an array of 12 dual-core glass waveguides on 250-μ m pitch that are tapered to a 20-μm pitch, simultaneously providing both pitch and spot-size conversion. At the wide end, the inner core matches the NA and mode profile of standard single-mode fiber. When drawn and tapered, the inner core "vanishes" and the outer core, surrounded by the clad, matches the NA and mode profile of the on-chip photonic waveguide. Ultradense high-efficiency coupling to an array of Si photonic waveguides is demonstrated using a 12-channel polarization-maintaining-fiber pigtailed tapered coupler. Coupling to Si waveguides is facilitated using SiON spot-size converters integrated into the Si photonic IC to provide 2-3-μm mode field diameters compatible with the tapered coupler. The tapered coupler achieves <1 dB coupling losses to photonic waveguides. Furthermore, eight-channel coupling is shown with less than -35 dB crosstalk between channels. Finally, a 640-Gb/s wavelength-division-multiplexing signal is coupled into four waveguides occupying 80μm of chip edge, providing 160-Gb/s per-channel bandwidths.

Original languageEnglish (US)
Article number5605213
Pages (from-to)475-482
Number of pages8
JournalJournal of Lightwave Technology
Issue number4
StatePublished - 2011
Externally publishedYes


  • Optical fiber couplers
  • Si photonics
  • optical waveguides
  • photonic packaging

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics


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