Characterization of refractive index change and fabrication of long period gratings in pure silica fiber by femtosecond laser radiation

Farid Ahmed, Hang Eun Joe, Byung Kwon Min, Martin B.G. Jun

Research output: Contribution to journalArticle

17 Citations (Scopus)


Ultrafast laser induced refractive index (RI) change in the core of a standard telecommunication fiber is quantified using the spectral shift of an in-fiber Bragg grating (FBG) based Fabry-Perot cavity. Measured RI change is used to design and then fabricate long period grating (LPG) in pure silica core single mode fiber (SMF) employing identical laser irradiation conditions used in core index characterization. A core length of 100 μm within the 10 mm long cavity structure is scanned with ultrafast laser pulses, and the corresponding spectral shift is used to calculate index modification. The index change of 0.000449 found in characterization process is used to simulate the LPG in pure silica fiber. Identical index modulation written in pure silica fiber by femtosecond laser radiation provides a rejection band that is in good agreement with the simulation results. The fabricated LPG sensors are also characterized for ambient temperature and RI.

Original languageEnglish
Pages (from-to)119-124
Number of pages6
JournalOptics and Laser Technology
Publication statusPublished - 2015 Jun 13


All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Electrical and Electronic Engineering

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