Counter-pumped optical fiber raman amplifier and its application in optical fiber communication system

摘要

The apparatus includes an optical fibre path of silica-based amplifier fibre that connects an input port and an output port, and a pump radiation input via WDM (13). The pump radiation is introduced at a wavelength lambda p less than a signal wavelength lambda s into the amplifier fibre such that it propagates in the fibre in an upstream direction towards the input port. Provided with the amplifier fibre is at least two lengths of fibre (L1,L2), with the sum of both lengths being at least 200m. An optical isolator is disposed between the two lengths such that passage of radiation of wavelength lambda s from the second to the first length is blocked. The pump path is closed upon itself and includes a portion of the amplifier fibre, the path selected such that the initial pump radiation can circulate in it. A second pump radiation of wavelength lambda p?'lambda p may be introduced into the pump path and a Bragg grating blocks its passage. Selected and placed Bragg gratings provide one or more optical cavities in the fibre ring, such that the input pump radiation is converted to the desired amplifier pump radiation. The wavelength lambda s may be 1310 nm, lambda p 1240 nm, and lambda p?' 1060 nm.