OPTICAL FIBER AND OPTICAL AMPLIFYING METHOD

摘要

PURPOSE:To suppress the daturating phenomenon of gain in an optical amplification using induced Raman dispersion by forming a sub-core applying large loss only to a specific wavelength in addition to a main core. CONSTITUTION:A loss applying part 4 is arranged close to the sub-core 3 along its longitudinal direction. Quartz glass to which impurity such as B2O3 is doped can be used as a base material for applying loss. Sufficient coupling is generated between the wave-guiding modes of both cores 2 and 3 at the secondary stokes wavelength lambdas1 of the induced Raman dispersion and coupling at the pump optical wavelength lambdap=1.318mum and the primary stokes optical wavelength lambdas1=1.401mum is suppressed down to a sufficiently low level to attain wavelength selective coupling. Namely, these coupling can be attained by setting up the core diameters of both the cores and refractive index difference between the core and clad to different values each other.