| 摘要 |
A method is disclosed for amplifying a light pulse (S) in an optical fiber ( 1 ), wherein a Raman pump signal (RPS) having a lower wavelength than the light pulse (S) is transmitted at a selected interval of time after the light pulse (S) into an end (IA) of an optical fiber( 1 ), with dispersion such that the Raman pump signal (RPS) travels faster through the fiber( 1 ) than the light pulse(S) and reaches and enhances the light pulse (S) after the light pulse has travelled along a selected distance (d 1 ) through the fiber, wherein the Raman pump signal (RPS) is ramped in a substantially linear manner such that the amplification increases with the distance along which the light pulse has travelled along the length of the fiber from A<SUB>1</SUB>=S<SUB>1</SUB>+RPS<SUB>min </SUB>at a distance d 1 to A<SUB>2</SUB>=S+RPS<SUB>max </SUB>at a distance d<SUB>2</SUB>>d<SUB>1 </SUB>from said end (IA) of the fiber 1 and such that the Raman gain increase is substantially similar to the fiber losses of the amplified signal. The use of a ramped Raman pump signal (RSP) mitigates Stimulated Brillouin Scattering (SBS) in the fiber ( 1 ) and extends the operational range of a fiber optical sensing system. |
