Tailoring of the brillouin gain profile for fiber-based sensor systems and networks

We outline a design procedure and show some resulting Brillouin-tailored optical fibers for use in fiber-based sensor systems and networks. Brillouin scattering can be utilized, for example, in distributed temperature sensors. However, it can also be detrimental, such as when high power per-unit-bandwidth is propagated over long distances. Based on models we have developed, several Brillouin-tailored fibers were designed and manufactured, each potentially targeting a unique application. For example, a fiber was designed and fabricated that operates with two Brillouin frequencies that have been gain-equalized to within 0.5 dB, and a frequency difference of 175 MHz. Temperature sensing may be accomplished by the direct detection of the beat frequency between the two Stokes' lines. In another example, an optical fiber was designed and fabricated with eight acoustic modes that have all been Brillouin gain-equalized to within 3 dB, over a frequency span of nearly 1 GHz. In another example, fiber optic sensors that require the propagation of narrow linewidth signals over longer distances are limited by Stimulated Brillouin Scattering (SBS). A fiber has been designed and fabricated that has a Brillouin-threshold that is increased by > 10 dB relative to traditional fibers with the same optical mode size.