Tunable Delay Lines in Silicon Photonics: Coupled Resonators and Photonic Crystals, a Comparison

A. Melloni, A. Canciamilla, C. Ferrari, F. Morichetti, Liam O'Faolain, T. F. Krauss, R. De La Rue, A. Samarelli, M. Sorel

Research output: Contribution to journalArticlepeer-review

197 Citations (Scopus)


In this paper, we report a direct comparison between coupled resonator optical waveguides (CROWs) and photonic crystal waveguides (PhCWs), which have both been exploited as tunable delay lines. The two structures were fabricated on the same silicon-on-insulator (SOI) technological platform, with the same fabrication facilities and evaluated under the same signal bit-rate conditions. We compare the frequency- and time-domain response of the two structures; the physical mechanism underlying the tuning of the delay; the main limits induced by loss, dispersion, and structural disorder; and the impact of CROW and PhCW tunable delay lines on the transmission of data stream intensity and phase modulated up to 100 Gb/s. The main result of this study is that, in the considered domain of applications, CROWs and PhCWs behave much more similarly than one would expect. At data rates around 100 Gb/s, CROWs and PhCWs can be placed in competition. Lower data rates, where longer absolute delays are required and propagation loss becomes a critical issue, are the preferred domain of CROWs fabricated with large ring resonators, while at data rates in the terabit range, PhCWs remain the leading technology.

Original languageEnglish
Pages (from-to)181-194
Number of pages14
JournalIEEE Photonics Journal
Issue number2
Publication statusPublished - Apr 2010


  • Slow light
  • delay lines
  • coupled resonators
  • rings
  • silicon photonics
  • photonic crystals
  • differential quadrature phase shift keying (DQPSK)
  • GBIT/S


Dive into the research topics of 'Tunable Delay Lines in Silicon Photonics: Coupled Resonators and Photonic Crystals, a Comparison'. Together they form a unique fingerprint.

Cite this