Near-constant time delay response of fiber grating Sagnac loop filters

Xuwen Shu*, Donghui Zhao, Lin Zhang, Kate Sugden, Ian Bennion

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


A theoretical and experimental investigation of the time delay characteristics of fiber Bragg grating-based Sagnac loops (FBGSLs) is presented. Analytic expressions for the phase and time delay of the FBGSL have been derived and excellent agreement is found between their predictions and experimental results for configurations incorporating uniform-period and chirped-period gratings. For symmetrical grating structures, it is found that the FBGSL time delay response is similar to that of the incorporated grating; with asymmetrical gratings, the FBGSL response is quite different. It is shown that wavelength-division-multiplexing filters exhibiting near-zero dispersion characteristics can be implemented using FBGSLs.

Original languageEnglish
Pages (from-to)1127-1129
Number of pages3
JournalIEEE Photonics Technology Letters
Issue number8
Publication statusPublished - Aug 2002


  • near-constant passband time delay
  • time delay response
  • Sagnac loop
  • filters
  • fiber Bragg grating
  • optical filter


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