Behavior of a hollow core photonic crystal fiber under high radial pressure for downhole application

Abstract

Pressure fiber sensors play an important role in downhole high pressure measurements to withstand long term operation. The purpose of this paper is to present an application of hollow core photonic crystal fiber (HC-PCF) as a high pressure sensor head for downhole application based on dispersion variation. We used a high pressure stainless steel unit to exert pressure on the sensor. The experimental results show that different wavelengths based on sagnac loop interferometer have additive sensitivities from 5 × 10−5 nm/psi at 1480 nm to 1.3 × 10−3 nm/psi at 1680 nm. We developed a simulation to understand the reason for difference in sensitivity of wavelengths and also the relationship between deformation of HC-PCF and dispersion variation under pressure. For this purpose, by using the finite element method, we investigated the effect of structural variation of HC-PCF on spectral transformation of two linear polarizations under 1000 psi pressure. The simulation and experimental results show exponential decay behavior of dispersion variation from −3.4 × 10−6 1/psi to −1.3 × 10−6 1/psi and from −5 × 10−6 1/psi to −1.8 × 10−6 1/psi, respectively, which were in a good accordance with each other.

Studies on Temperature and Strain Sensitivities of a Few-Mode Critical Wavelength Fiber Optic Sensor

“…, at the operational wavelength planned, the fiber supports the fundamental core mode, LP01, and does not support the LP11 mode, but does support the first circularly symmetric high order core mode, LP02, propagating in the fiber [16]. Using the finite element analysis method [17,18], the simulated mode field distributions of the propagating core modes (at a wavelength of 1550nm), LP01 and LP02, are shown in Fig. 1(c) and (d), respectively.…”

Group Polarimetric Pressure Sensitivity of an Elliptical-Core Side-Hole Fiber at Telecommunication Wavelengths

“…For polarization maintaining fibers, the relationship between fiber length (L), operation wavelength (λ), group birefringence (B g = λ2/2LΔl), wavelength spacing of the peaks (Δλ) and the group polarimetric sensitivity (K P − g ) in the sagnac loop interferometer is defined by [3]:…”

“…To understand the impact of radial pressure on different wavelength changes and also the effects of different pressure intervals on polarimetric properties, we simulated our EC-SHF by coupling the Mechanics and RF modules of the Comsol Multiphysics commercial software [3]. With these modules, we were able to determine the changes in spectral transformation and mode confinement of EC-SHF's cross section resulting from radial pressure changes.…”

Manifestations of Nanomaterials in Development of Advanced Sensors for Defense Applications

“…Due to significant variations in Young's modulus because of the air columns running along the fiber length of HC-PBF or PCFs, these systems prove to be good sensors for axial strain applied acoustic pressure parameter sensing. Recently, little effort has been put into developing the PCF-based acousto-optic devices including hollow-core PCF [16][17][18], solidcore PCF [19,20], dual-core PCF [21], twin-core PCF [22], and highly birefringent PCFs [23,24]. Pang and Jin [17] have demonstrated a Michelson interferometerbased system using a 5.7 m fiber to sense the frequencies in a wide range (40-3000 Hz) at 1550 nm, with phase shift as the function of pressure.…”

“…Yang et al [16] have used the similar interferometric technique using an etched and then polymer-coated fiber to yield high sensitivity. A Sagnac interferometer has been used by a group [18] to detect the pressures (0-4000 psi) using a wavelength shift as the conversion parameter. However, the challenge of a miniaturized system for typical sonar frequency (especially, low acoustic frequencies between 5 and 200 Hz) detection and that too with a good sensitivity is always on the anvil.…”