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Proceedings Paper

Near field diffraction of phase-shifted phase grating for side-writing fiber Bragg gratings
Author(s): Yunlong Sheng; Li Sun; Joshua E. Rothenberg; Hongpu Li; Ying Wang
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Paper Abstract

The fiber Bragg grating (FBG) with a very high count, up to N=80, identical channels for dispersion compensators has been commercialized. The design utilizes the phase-only sampling, which requires η / N time higher refractive index modulation than the N times required by the amplitude sampling design. The phase sampling is implemented by inserting phase shifts in the FBG. Hence, the positive valued coupling coefficients of the FBG become complex-valued, which greatly increase the functionality and spectral performance of the FBG. In the fabrication of the phase-shifted FBG we find that the phase shifts in the phase mask for writing the FBG are not replicated into the FBG, as believed by many people, but are split into two half-magnitude phase-shifts due to the near field diffraction. We show the split of the phase shift by using the Finite Difference in Time Domain (FDTD) analysis and we show that this split of the phase shifts results in the FBG spectral asymmetry by a physical model of the phase-only sampling function distortion and by the FBG experiments. The new pre-compensating phase mask technique is introduced to remove the errors and therefore ensure the success of the high count multiple channel FBGs.

Paper Details

Date Published: 20 January 2006
PDF: 8 pages
Proc. SPIE 6027, ICO20: Optical Information Processing, 602707 (20 January 2006); doi: 10.1117/12.667703
Show Author Affiliations
Yunlong Sheng, Univ. Laval (Canada)
Li Sun, Univ. Laval (Canada)
Joshua E. Rothenberg, Northrop Grumman Corp. (United States)
Hongpu Li, Shizuoka Univ. (Japan)
Ying Wang, Kiara Networks, Inc. (United States)

Published in SPIE Proceedings Vol. 6027:
ICO20: Optical Information Processing
Yunlong Sheng; Songlin Zhuang; Yimo Zhang, Editor(s)

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