FIELD: fibre light guides.
SUBSTANCE: active fibre light guide with a variable cross-sectional area, a method for its manufacture and an optical signal amplifier based on it. The claimed fibre light guide contains an active core doped with at least one active element and at least two reflective shells; the cross-sectional area of the core and the cross-sectional area of the reflective cladding adjacent to the core continuously change along the length of the optical fibre so that the maximum total cross-sectional area Smax of the core and the said reflective cladding is at least twice the minimum total area S min of the transverse section of the core and the specified reflective shell. At the same time, at least one reflective cladding of the fibre light guide contains at least one modified section configured to reduce the power of the pump radiation propagating along the light guide in at least one reflective cladding after passing through the specified modified section. Moreover, at least one modified section of the reflective cladding is located in the region along the axis of the light guide, where the total cross-sectional area Sint of the core and the reflective cladding adjacent to the core satisfies the following condition: 1.5×Smin<Sint≤Smax. Also proposed is a method for manufacturing a fibre light guide and an optical amplifier based on a fibre light guide.
EFFECT: creation of an active light guide with a varying cross-sectional area of the core and adjacent reflective cladding, which is capable of operating without degradation of its characteristics, including the integrity of the light guide itself, for a long time at a high level of pump power introduced into the said active light guide from the side of its thick end into a reflective cladding adjacent to the core and a decrease, up to complete elimination, of the pump power reaching the thin part of the fibre.
15 cl, 10 dwg
