L-shaped fiber-chip grating couplers with high directionality and low reflectivity fabricated with deep-UV lithography Journal Articles uri icon

  • Overview
  • Research
  • Identity
  • Additional Document Info
  • View All


  • Grating couplers enable position-friendly interfacing of silicon chips by optical fibers. The conventional coupler designs call upon comparatively complex architectures to afford efficient light coupling to sub-micron silicon-on-insulator (SOI) waveguides. Conversely, the blazing effect in double-etched gratings provides high coupling efficiency with reduced fabrication intricacy. In this Letter, we demonstrate for the first time, to the best of our knowledge, the realization of an ultra-directional L-shaped grating coupler, seamlessly fabricated by using 193 nm deep-ultraviolet (deep-UV) lithography. We also include a subwavelength index engineered waveguide-to-grating transition that provides an eight-fold reduction of the grating reflectivity, down to 1% (-20  dB). A measured coupling efficiency of -2.7  dB (54%) is achieved, with a bandwidth of 62 nm. These results open promising prospects for the implementation of efficient, robust, and cost-effective coupling interfaces for sub-micrometric SOI waveguides, as desired for large-volume applications in silicon photonics.


  • Benedikovic, Daniel
  • Alonso-Ramos, Carlos
  • Pérez-Galacho, Diego
  • Guerber, Sylvain
  • Vakarin, Vladyslav
  • Marcaud, Guillaume
  • Le Roux, Xavier
  • Cassan, Eric
  • Marris-Morini, Delphine
  • Cheben, Pavel
  • Boeuf, Frédéric
  • Baudot, Charles
  • Vivien, Laurent

publication date

  • September 1, 2017