Sensing characteristics of the rocking filters in microstructured fibers optimized for hydrostatic pressure measurements

Abstract

We report on the sensing characteristics of rocking filters fabricated in two microstructured fibers with enhanced polarimetric sensitivity to hydrostatic pressure. The filter fabricated in the first fiber shows a very high sensitivity to pressure ranging from 16.2 to 43.4 nm/MPa, depending on the resonance order and features an extremely low cross-sensitivity between pressure and temperature 28 ÷ 89 × 10(3) K/MPa. The filter fabricated in the second fiber has an extreme sensitivity to pressure ranging from -72.6 to -177 nm/MPa, but a less favorable cross-sensitivity between pressure and temperature of 1.05 ÷ 3.50 × 10(3) K/MPa. These characteristics allow using the rocking filters for pressure measurements with mbar resolution.

Nonlinear frequency conversion in a birefringent microstructured fiber tuned by externally applied hydrostatic pressure

“…The proposed sensor has sensitivity about two times greater than the figure of 0.18 THz∕MPa reported for the Bragg grating embedded in a laminated composite [16] and almost three orders of magnitude lower than the record high sensitivity of 240 THz∕MPa reported recently for rocking filters [11]. The most important drawback of the proposed sensing concept is the limitation of the operation range to pressure at which the fiber phase birefringence becomes null.…”

“…Birefringent microstrutured fibers with very high polarimetric sensitivity to pressure and very low sensitivity to temperature have been demonstrated recently, thus opening new perspectives for fiber-based pressure sensing [10,11]. For example, it is demonstrated in Ref.…”

“…For example, it is demonstrated in Ref. [11] that a rocking filter fabricated in such a fiber shows extremely high sensitivity to hydrostatic pressure, reaching several THz/MPa. In this work, we propose to use a microstructured fiber with increased sensitivity to hydrostatic pressure as a nonlinear fiber-optic sensor.…”

Simplifying the design of microstructured optical fibre pressure sensors

“…( ∂B/∂P  = 2.52 × 10 −7  bar −1 ) 6 and the specially designed fibre endowed with a triangular pattern of air holes described by A. Anuskiewicz et al . ( ∂B/∂P  = 8.89 × 10 −7  bar −1 ) 7 , whose designs were optimized for pressure sensing. The fabrication process of these fibres, however, is much more complex than the one used for obtaining the embedded-core fibres, which requires only a relatively simple fibre drawing process.…”

“…Hydrostatic pressure, temperature, refractive index, strain and curvature are some examples of the parameters that can be monitored by using optical fibres 1 . In this context, numerous technologies – such as Bragg and long-period gratings 2, 3 , fibre tapers 4 , multimode interferometers 5 , rocking filters 6, 7 , photonic-crystal fibres (PCFs) 8, 9 or combinations thereof – have been used to explore the potential of optical fibres in performing sensing measurements. Advantages of optical fibre-based sensors include high sensitivity, electromagnetic immunity and the possibility of functioning in harsh environments.…”