Analytical Modelling of a Refractive Index Sensor Based on an Intrinsic Micro Fabry-Perot Interferometer

Abstract

In this work a refractive index sensor based on a combination of the non-dispersive sensing (NDS) and the Tunable Laser Spectroscopy (TLS) principles is presented. Here, in order to have one reference and one measurement channel a single-beam dual-path configuration is used for implementing the NDS principle. These channels are monitored with a couple of identical optical detectors which are correlated to calculate the overall sensor response, called here the depth of modulation. It is shown that this is useful to minimize drifting errors due to source power variations. Furthermore, a comprehensive analysis of a refractive index sensing setup, based on an intrinsic micro Fabry-Perot Interferometer (FPI) is described. Here, the changes over the FPI pattern as the exit refractive index is varied are analytically modelled by using the characteristic matrix method. Additionally, our simulated results are supported by experimental measurements which are also provided. Finally it is shown that by using this principle a simple refractive index sensor with a resolution in the order of 2.15 × 10−4 RIU can be implemented by using a couple of standard and low cost photodetectors.

Reflective Fiber Surface Plasmon Resonance Sensor for High-Sensitive Mercury Ion Detection

“…Under the same conditions, fiber reflective SPR sensors with Hg 2+ sensitive films of 5 layers, 10 layers, and 15 layers were fabricated, named as (CS/PAA) 5 , (CS/PAA) 10 , and (CS/PAA) 15 , respectively. These fiber sensors were immersed in 50-µM Hg 2+ solution, and the output spectra were recorded with the detection time, respectively, as shown in Figure 8.…”

“…The wavelength shifts at equilibrium are 15 nm, 20 nm, and 6 nm, respectively. When measuring the same concentration of Hg 2+ solution, the (CS/PAA) 10 sensor has the largest spectral wavelength shift, namely the highest sensitivity. Therefore, the optimal number of layers of the sensitive film was selected as 10 in the following experiments.…”

“…In contrast, fiber optic sensors have unique advantages, such as multiplexing, high flexibility, high sensitivity, remote sensing, low cost, and immunity to electromagnetic interference [9][10][11], which play an increasingly important role in the detection of heavy metal ions. In recent years, researchers proposed many fiber sensing technologies to detect heavy metal ions, including: Evanescent wave absorption [12], Mach-Zehnder interferometer [13], fluorescence [14], and surface plasmon resonance (SPR) [15].…”

Monitoring the Growth of a Microbubble Generated Photothermally onto an Optical Fiber by Means Fabry–Perot Interferometry

“…Nowadays, interferometric optical fiber sensors have attracted broad interest for their applications in sensing temperature, refractive index, strain measurement, pressure, acoustic waves, vibration, magnetic field, and voltage. Most of them are studied by generating a microbubble on the tip of an optical fiber, which is considered to be a resonant cavity formed by the vapor–liquid interface and the fiber tip [ 12 , 13 , 14 , 15 , 16 , 17 ].…”

Optical Fiber FP Sensor for Simultaneous Measurement of Refractive Index and Temperature Based on the Empirical Mode Decomposition Algorithm

“…From these, the sensors based on the Fabry-Perot Interferometer (FPI) are particularly attractive since these can be easily fabricated. Typically, the FPI can be implemented by forming an air cavity at the tip of the optical fiber which can be sealed [2][3][4][5][6] or open to the external medium [7,8]. The reflection spectrum of these FPIs is formed by a set of fringes which can be described by a quasi-sinusoidal waveform.…”