Silicon Based 1 × M Wavelength Selective Switch Using Arrayed Waveguide Gratings with Fold-Back Waveguides

Fumi Nakamura, Hideaki Asakura, Keijiro Suzuki, Ken Tanizawa, Minoru Ohtsuka, Nobuyuki Yokoyama, Kazuyuki Matsumaro, Miyoshi Seki, Kazuhiro Ikeda, Shu Namiki, Hitoshi Kawashima, Hiroyuki Tsuda

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


The design of a novel 1 × M fold-back type wavelength selective switch (WSS), which has fewer waveguide crossings than a conventional integrated WSS, is reported. The WSS is composed of interleavers, 1 × M optical switches, and arrayed waveguide gratings (AWGs). Switches are combined with AWGs by fold-back waveguides, and each AWG works as both a demultiplexer and multiplexer thus avoiding center wavelength mismatch caused by fabrication errors. Waveguide crossings cause excess crosstalk and loss in lightwave circuits. By using a fold-back architecture the number of crossings can be reduced to less than half that of a conventional design. We discuss the operating principle, the design method, and the scalability of the fold-back type WSS. Furthermore, the switching operation of a 200-GHz spacing, 20-channel, 1 × 2 silicon WSS in a fold-back configuration on a 5 mm × 10 mm SOI chip is demonstrated. This has 15 waveguide crossings in a path, of which six are additional crossings with monitor waveguides. The average insertion loss and average extinction ratio are 29.6 dB and 10.9 dB, respectively.

Original languageEnglish
Article number9311797
Pages (from-to)2413-2420
Number of pages8
JournalJournal of Lightwave Technology
Issue number8
Publication statusPublished - 2021 Apr 15
Externally publishedYes


  • Arrayed waveguide grating
  • optical networking
  • waveguide crossing
  • wavelength division multiplexing
  • wavelength selective switch

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics


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