Versatile characterization of specialty fibers using the phase-sensitive optical low-coherence reflectometry technique

Emergence of new fibers families induces considerable requirements in terms of characterization and metrology (group delay, chromatic dispersion, birefringence, bending losses, etc.). The optical low-coherence reflectometry (OLCR) technique is demonstrated as a versatile method for the characterization of most types of optical fiber. A synthesis of multiple analysis concerning different families of specialty fibers including rare-earth-doped fibers, few-mode fibers, and microstructured fibers will be presented. OLCR allows measuring precisely the group velocity dispersion value for both polarization modes and birefringence. It is also possible to measure small refractive-index variations in a pumped Erbium-doped fiber. Unique dispersive properties of higher order modes fiber offer novel solutions for dispersion compensation or nonlinear effects management. OLCR can allow each LP mode characterization without the requirement for mode converters. A new method, called "time-wavelength reflection mapping," based on the OLCR interferogram processing is applied to the determination of chromatic dispersion of each guided LP mode whatever their group index. Finally, different characterization results concerning photonics crystal fibers with guiding based on the conventional total internal reflection principle (high-index guiding) or photonic bandgap effect (low-index guiding) will be presented.