In this paper, the effects of the asymmetric refractive index change profile on the reflection spectra of multimode fiber Bragg gratings (MMFBGs) are experimentally and theoretically investigated. Different guided modes in a multimode fiber (MMF) are coupled with each other and the sub-reflection peaks are generated if the refractive index change profile of the MMFBG is asymmetric in the cross section of the fiber core. It is found that by increasing the UV exposure, the reflectivities of the main reflection peaks are decreased, the reflectivities of the sub-peaks are increased, even higher than the main reflection peaks, which indicate the grating becomes more asymmetric with increasing the UV exposure. It is further shown that an MMFBG is much more sensitive to the polarization state of the injected light compared with an SMFBG. The numerical simulations are carried out to explain the excitation condition dependence of the reflection spectra of MMFBG, which agree well with the experimental results.

Date Published: 12 October 2005
PDF: 8 pages
Proc. SPIE 5970, Photonic Applications in Devices and Communication Systems, 597008 (12 October 2005); doi: 10.1117/12.628783

Published in SPIE Proceedings Vol. 5970:
Photonic Applications in Devices and Communication Systems
Peter Mascher; John C. Cartledge; Andrew Peter Knights; David V. Plant, Editor(s)