We report a thorough analysis on the Brillouin frequency shift as a function of geometrical parameters in a silica optical fiber consisting of triple-layered structure, GeO2-doped core, P2O5, and F co-doped inner cladding, and pure silica outer cladding. General characteristic equations for the Brillouin frequency shift were analytically derived and analyzed for various fiber parameters. In experiments, three-layered optical fibers were fabricated and their Brillouin frequency shifts were measured in the wavelength region of 1.55 μm by a pump-probe technique. The longitudinal acoustic velocity in each layer was found significantly affected by the thermal stress as well as the dopant concentrations. We confirmed both in theory and experiment that the inner cladding of a three-layered optical fiber does provide a new degree of freedom in precise control of the Brillouin frequency shift.
Bibliographical noteFunding Information:
Manuscript received September 6, 2002; revised May 14, 2003. This work was supported in part by the KOSEF through the Ultra-Fast-Fiber-Optic Networks Research Center, the Korean Ministry of Education through the BK21 Program, and the ITRC-CHOAN program.
All Science Journal Classification (ASJC) codes
- Atomic and Molecular Physics, and Optics