Large dynamic range pressure sensor based on two semicircle-holes microstructured fiber

Abstract

This paper presents a sensitive and large dynamic range pressure sensor based on a novel birefringence microstructured optical fiber (MOF) deployed in a Sagnac interferometer configuration. The MOF has two large semicircle holes in the cladding and a rectangular strut with germanium-doped core in the center. The fiber structure permits surrounding pressure to induce large effective index difference between the two polarized modes. The calculated and measured group birefringence of the fiber are 1.49 × 10−4, 1.23 × 10−4, respectively, at the wavelength of 1550 nm. Experimental results shown that the pressure sensitivity of the sensor varied from 45,000 pm/MPa to 50,000 pm/MPa, and minimum detectable pressure of 80 Pa and dynamic range of better than 116 dB could be achieved with the novel fiber sensor. The proposed sensor could be used in harsh environment and is an ideal candidate for downhole applications where high pressure measurement at elevated temperature up to 250 °C is needed.

Multifunctional Smart Optical Fibers: Materials, Fabrication, and Sensing Applications

“…Then those capillaries with identical or different dimensions are used to stack the air-hole structure of the PCF or of other types of MOFs [77]. Apart from the PCFs with hexagonal air-hole structure that have been demonstrated, MOFs with suspended core [78], semicircular holes [79], "butterfly" structure [80], and super-lattice structure [81] have been successfully fabricated using this technique. Because of the flexibility of the stacking method, almost any kind of microstructure with any material can be made in this manner.…”

“…Typically, this type of fiber is called a polarization-maintaining fiber (PMF). A PMF can also be created by introducing an asymmetrical air-hole structure, for example, a PM-PCF [105], a polarization-maintaining hollow-core fiber [106], a high-birefringence suspended-core fiber (HB-SCF) [78], or two semicircular side-hole MOFs [79]. Figure 4c shows a typical SI configuration using PMF.…”

“…The geometrical difference between the two polarization axes is very limited, especially when the fiber is subject to external perturbations such as pressure change. Other microstructures are then developed to enhance pressure measurement performance further, for instance, the "butterfly"-type MOF [80], the semicircular-hole MOF [79], and the side-hole fiber [113]. Among these special microstructures, the highest pressure demonstrated with the SI configuration was based on the semicircular-hole MOF, showing a sensitivity up to ~50 nm/MPa and a large dynamic range of 116 dB [79].…”

“…Other microstructures are then developed to enhance pressure measurement performance further, for instance, the "butterfly"-type MOF [80], the semicircular-hole MOF [79], and the side-hole fiber [113]. Among these special microstructures, the highest pressure demonstrated with the SI configuration was based on the semicircular-hole MOF, showing a sensitivity up to ~50 nm/MPa and a large dynamic range of 116 dB [79]. Table 3 lists the state-of-the-art specialty optical fibers developed for pressure measurement and their corresponding performance.…”

Fabrication of high‐fracture‐strength and gas‐tightness PDC films via PIP process for pressure sensor application

“…Because of the limitation of materials, the fabrication of pressure sensors used in harsh environments is a still challenging task 1,2 . The traditional Si‐based pressure sensors cannot function when the device is operated at the temperature above 350°C 3,4 . Ceramics have combined properties of low weight, high‐temperature strength, and environmental stability, and are good candidate materials for sensing especially in harsh environments 5–8 .…”