Coupled-resonator optical waveguides: Q-factor and disorder influence

Jure Grgic, Enrico Campaioli, Søren Raza, Paolo Bassi, N. Asger Mortensen

Research output: Contribution to journalJournal articleResearchpeer-review


Coupled resonator optical waveguides (CROW) can significantly reduce light propagation pulse velocity due to pronounced dispersion properties. A number of interesting applications have been proposed to benefit from such slow-light propagation. Unfortunately, the inevitable presence of disorder, imperfections, and a finite Q value may heavily affect the otherwise attractive properties of CROWs. We show how finite a Q factor limits the maximum attainable group delay time; the group index is limited by Q, but equally important the feasible device length is itself also limited by damping resulting from a finite Q. Adding the additional effects of disorder to this picture, limitations become even more severe due to destructive interference phenomena, eventually in the form of Anderson localization. Simple analytical considerations demonstrate that the maximum attainable delay time in CROWs is limited by the intrinsic photon lifetime of a single resonator.
Original languageEnglish
JournalOptical and Quantum Electronics
Issue number8
Pages (from-to)511-519
Publication statusPublished - 2011


  • Group delay
  • Coupled-resonator optical waveguide (CROW)
  • Slow light
  • Photonic crystal waveguides


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