Measuring brillouin backscatter from an optical fibre using channelisation
AssigneeSchlumberger Technology Corporation
InventorArthur H. Hartog
Life of this patent
Estimating the term…
Abstract
Methods and apparatus for measuring Brillouin backscattering from an optical fiber. A pulse of light with a first frequency is launched into an optical fiber. Backscattered light is received from the fiber, which includes Brillouin spectral line at a second frequency shifted from the first. The Brillouin spectral line varies with time and distance along the fiber. A signal representative of the backscattered light is obtained. The signal is divided into several components, each with a different frequency. The components are further treated, and one or more properties of the Brillouin spectral line are determined.
Claims24
A method for measuring Brillouin backscattering from an optical fibre comprising:
- launching a probe pulse of coherent light with frequency f0 into an optical fibre;
- receiving backscattered light from the optical fibre that includes at least one Brillouin spectral line at a frequency fB(t) shifted from f0 by a Brillouin shift, the Brillouin spectral line varying with time and distance along the fibre;
- obtaining a signal representative of the received backscattered light;
- dividing the signal into a plurality of signal components each having a different frequency band and delivering each signal component to a detection channel;
- in each detection channel:
- detecting the signal component using a detector to generate an electrical signal;
- and
- digitising the electrical signal using an analog-to-digital converter to sample the electrical signal and generate a sequence of digital samples representing the electrical signal;
- and
- processing the digital samples from the detection channels to determine one or more properties of the Brillouin spectral line of the received backscattered light as a function of time/distance along the optical fibre.
Apparatus for measuring Brillouin backscattering from an optical fibre comprising:
- a first optical source operable to generate probe pulses of coherent light at a frequency f0 and launch probe pulses into an optical fibre;
- a receiver operable to receive backscattered light from the optical fibre that includes at least one Brillouin spectral line at a frequency fB(t) shifted from f0 by a Brillouin shift, the Brillouin spectral line varying with time and distance along the fibre, and to deliver a signal representative of the received backscattered light;
- a divider operable to divide the signal into a plurality of signal components each having a different frequency band and deliver each component to a detection channel, each detection channel comprising:
- a detector operable to detect the signal component and generate an electrical signal;
- and
- an analog-to-digital converter operable to digitise the electrical signal by sampling to generate a sequence of digital samples representing the electrical signal;
- and
- a processor operable to process the digital samples from the detection channels to determine one or more properties of the Brillouin spectral line of the received backscattered light as a function of time/distance along the fibre.
Dependencies are inferred from the claim text.