| Popis: |
The uncoated optical fiber has been extensively researched as an optomechanical sensor since it can achieve substance identification of the surrounding media by exciting and detecting transverse acoustic waves via forward stimulated Brillouin scattering (FSBS), yet within danger of being easily broken. Although polyimide-coating fibers are reported to allow transverse acoustic waves transmission to the coating for reaching the ambient while maintaining the mechanical properties of the fiber, it still suffers from the problems of humidity sensitivity and spectral instability. Here, we propose for the first time a robust distributed FSBS-based optomechanical sensor using an aluminized coating optical fiber. Benefiting from the quasi-acoustic impedance matching condition of the aluminized coating and silica core-cladding, aluminized coating optical fibers not only have stronger mechanical properties and higher transverse acoustic wave transmission efficiency but also has a higher signal-to-noise ratio, compared to the polyimide-coating fibers. The distributed measurement ability is verified by identifying air and water around the aluminized coating optical fiber with a spatial resolution of 2 m. In addition, the proposed sensor is immune to the external relative humidity changes, which is a preponderance for liquid acoustic impedance measurements. |
