Device for concatenation of phase-shifted long-period grating and its application as gain-flattening fiber filter

Yinian Zhu, Beatrys M. Lacquet, Pieter L. Swart, Stephanus J. Spammer, Ping Shum, Chao Lu

Research output: Journal article publicationJournal articleAcademic researchpeer-review

6 Citations (Scopus)


The transmission characteristics of phase-shifted long-period gratings (LPGs) are simulated theoretically using coupled-mode theory and the fundamental-matrix method. A phase-shifted LPG device cascaded with another uniform LPG can be used to flatten the gain spectrum of an erbium-doped fiber amplifier (EDFA) with three gain peaks. The results of all simulations have shown that a broadband amplifier with a 0.7-dB peak-to-peak gain variation over 36 nm can be realized practically. Using our designed and fabricated device, the experimental results show that the 3-dB bandwidth of the flattened EDFA is increased from 18 to 46 nm for an unequalized spectrum. The gain ripple over that bandwidth is reduced to approximately 0.9 dB. The improvement by a factor of 2 to 3 is realized in the sprectral performance. Such a gain-flattening fiber filter is indeed plausible and has a practical application in dense wavelength-division multiplexed (DWDM) telecommunication systems.
Original languageEnglish
Pages (from-to)1445-1450
Number of pages6
JournalOptical Engineering
Issue number5
Publication statusPublished - 1 May 2003
Externally publishedYes


  • Coupled mode theory
  • Fiber Bragg grating
  • Gain flattening
  • Long-period gratings
  • Optical fiber filter
  • Phase-shifted

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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