Special Issue "Optical Fiber Interferometric Sensors: New Production Methodologies and Novel Applications"

A special issue of Photonics (ISSN 2304-6732). This special issue belongs to the section "Lasers, Light Sources and Sensors".

Deadline for manuscript submissions: closed (31 May 2021) | Viewed by 12514

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editors

Prof. Dr. Paulo André
E-Mail Website
Guest Editor
Department of Electrical and Computer Engineering and Instituto de Telecomunicações, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal
Interests: study and simulation of optoelectronics components; fiber Bragg gratings; integrated optics in sol-gel substrates; passive optical networks; big data processing
Special Issues, Collections and Topics in MDPI journals
Dr. Nélia J. Alberto
E-Mail Website
Guest Editor
Instituto de Telecomunicações and University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
Interests: optical fiber sensors; fiber Bragg gratings; fiber sensors applications; biosensing
Special Issues, Collections and Topics in MDPI journals
Dr. Maria de Fátima Domingues
E-Mail Website
Guest Editor
Instituto de Telecomunicações, Campus Universitário de Santiago, P-3810-193 Aveiro, Portugal
Interests: optical fiber sensors; fiber Bragg gratings; Fabry-Perot interformetric sensors; eHealth applications; gait analysis; wearable sensing devices
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Optical fiber interferometric sensors have been widely investigated for potential application in many situations, such as, for example, monitoring temperature, strain, pressure, and most recently, in the detection and characterization of different physical, chemical, and also physiological parameters.
This Special Issue will focus on current state-of-the-art research in optical fiber interferometric sensors, covering recent technological improvements, new production methodologies, and emerging applications.
Both original research papers and review articles describing current state-of-the-art innovations in this research field are welcome. We hope this SI will provide you an overview of the present status and future outlook of the aforementioned topics.

The manuscripts should cover, but are not limited to, the following topics:

  • New and/or low-cost interferometers production methods
  • Novel optical fibers and Fabry-Perot, Mach-Zehnder, Michelson, and Sagnac-based sensors
  • Optical fiber interferometric based sensing for physical and chemical parameters
  • Optical fiber interferometric systems with microfluid integration
  • Low-cost, miniaturized, selective and multiparameter optical fiber interferometric devices
  • New bio/chemical probes for biomedical applications
  • Wearable/biomedical interferometric sensors
  • Advanced signal processing techniques
  • New interrogation techniques for interferometric sensors

Applications may include, but not limited to medical diagnostics and therapy instrumentation, structure health monitoring, chemical processing, metrology, aquaculture, oil and gas industry, robotics.

Dr. Maria de Fátima Domingues
Dr. Nélia J. Alberto
Prof. Paulo André
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Photonics is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (13 papers)

Order results
Result details
Select all
Export citation of selected articles as:

Editorial

Jump to: Research, Review

Editorial
Special Issue “Optical Fiber Interferometric Sensors: New Production Methodologies and Novel Applications”
Photonics 2021, 8(9), 389; https://doi.org/10.3390/photonics8090389 - 14 Sep 2021
Viewed by 698
Abstract
The collection of papers presented in this Special Issue (SI) portraits the state-of-the-art of photonic-based interferometric sensors, where new application areas were explored (such as spirometry) and novel sensitivity limits were achieved, using innovative sensing techniques for the monitoring of parameters, such as [...] Read more.
The collection of papers presented in this Special Issue (SI) portraits the state-of-the-art of photonic-based interferometric sensors, where new application areas were explored (such as spirometry) and novel sensitivity limits were achieved, using innovative sensing techniques for the monitoring of parameters, such as displacement, temperature or salinity. Full article

Research

Jump to: Editorial, Review

Communication
Optical Fiber Fabry–Perot Interferometer Based Spirometer: Design and Performance Evaluation
Photonics 2021, 8(8), 336; https://doi.org/10.3390/photonics8080336 - 15 Aug 2021
Cited by 1 | Viewed by 852
Abstract
Spirometry enables the diagnosis and monitoring of multiple respiratory diseases, such as asthma and chronic obstructive pulmonary disease (COPD). In this paper, we present an optical fiber-based device to evaluate the pulmonary capacity of individuals through spirometry. The proposed system consists of an [...] Read more.
Spirometry enables the diagnosis and monitoring of multiple respiratory diseases, such as asthma and chronic obstructive pulmonary disease (COPD). In this paper, we present an optical fiber-based device to evaluate the pulmonary capacity of individuals through spirometry. The proposed system consists of an optical fiber containing an intrinsic Fabry–Perot interferometer (FPI) micro-cavity attached to a 3D printed structure that converts the air flow into strain variations to the optical fiber, modulating the FPI spectral response. Besides providing the value of the flow, its direction is also determined, which enables a differentiation between inhale and exhale cycles of breathing. A simulation study was conducted to predict the system behavior with the air flow. The preliminary tests, performed with the FPI-based spirometer led to average values of forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) parameters of 4.40 L and 6.46 L, respectively, with an FEV1/FVC index (used as an airway function index) of 68.5%. An average value of 5.35 L/s was found for the peak expiratory flow (PEF). A comparison between the spirometry tests using the presented FPI system and a commercial electronic device showed that the proposed system is suitable to act as a reliable spirometer. Full article
Show Figures

Figure 1

Article
An Improved Large-Field Microscopic Speckle Interferometry System for Dynamic Displacement Measurement of MEMS
Photonics 2021, 8(7), 271; https://doi.org/10.3390/photonics8070271 - 09 Jul 2021
Cited by 4 | Viewed by 784
Abstract
The traditional microscopic speckle interferometer has limited applications in engineering due to its small field of view. In this paper, we propose a large-field microscopic speckle interferometer which embeds two doublet lens groups in the improved Mach–Zehnder optical path structure to expand its [...] Read more.
The traditional microscopic speckle interferometer has limited applications in engineering due to its small field of view. In this paper, we propose a large-field microscopic speckle interferometer which embeds two doublet lens groups in the improved Mach–Zehnder optical path structure to expand its field of view. At the same time, the new system can reduce the coherent noise of reflected light in the optical path. We use this new system to measure the dynamic displacement process of the entire surface of the microchips. The experimental results show that our improved measurement system can achieve large-field, real-time and high-precision dynamic measurement of micro-electromechanical systems (MEMS). Full article
Show Figures

Figure 1

Article
Measurement of Focal Length and Radius of Curvature for Spherical Lenses and Mirrors by Using Digital-Grating Moiré Effect
Photonics 2021, 8(7), 252; https://doi.org/10.3390/photonics8070252 - 01 Jul 2021
Cited by 2 | Viewed by 740
Abstract
This paper proposes the use of digital-grating moiré effect for measuring the focal lengths and radius of curvatures of biconvex and biconcave spherical simple lenses and spherical mirrors. Based on Fresnel diffraction, the equation for the electric field of propagated light passing through [...] Read more.
This paper proposes the use of digital-grating moiré effect for measuring the focal lengths and radius of curvatures of biconvex and biconcave spherical simple lenses and spherical mirrors. Based on Fresnel diffraction, the equation for the electric field of propagated light passing through the test samples was derived. Through digital image post processing, the recorded intensity on an observation screen was superimposed on a digital grating to generate a moiré pattern. On substituting the slant angle of the moiré pattern into the derived equation, the focal lengths and radius of curvatures could be determined. The experimental results successfully demonstrated the feasibility of the proposed method; the percent errors for focal length and radius of curvature measurement were less than 0.5%. The measurement uncertainty was analyzed and the correctness of the derived equation was confirmed through simulation. Because of the use of digital image post processing, the proposed method has advantages such as a simple set up, easy operation, high stability, high accuracy, and low cost. Thus, the method has considerable potential in relevant application. Full article
Show Figures

Figure 1

Article
Interferometric Instrument for Thickness Measurement on Blown Films
Photonics 2021, 8(7), 245; https://doi.org/10.3390/photonics8070245 - 29 Jun 2021
Cited by 2 | Viewed by 533
Abstract
Real-time measurement of plastic film thickness during production is extremely important to guarantee planarity of the final film. Standard techniques are based on capacitive measurements, in close contact with the film. These techniques require continuous calibration and temperature compensation, while their contact can [...] Read more.
Real-time measurement of plastic film thickness during production is extremely important to guarantee planarity of the final film. Standard techniques are based on capacitive measurements, in close contact with the film. These techniques require continuous calibration and temperature compensation, while their contact can damage the film. Different optical contactless techniques are described in literature, but none has found application to real production, due to the strong vibration of the films. We propose a new structure of low-coherence fiber interferometer able to measure blown film thickness during productions. The novel fiber-optic setup is a cross between an autocorrelator and a white light interferometer, taking the advantages of both approaches. Full article
Show Figures

Figure 1

Article
New Methods to Seismic Monitoring: Laboratory Comparative Study of Michelson Fiber-Optic Interferometer and Pneumatic Measurement Systems
Photonics 2021, 8(5), 147; https://doi.org/10.3390/photonics8050147 - 28 Apr 2021
Cited by 2 | Viewed by 742
Abstract
New possibilities of vibration monitoring can be found in completely different physical approaches, where all measuring technology is currently based on sensors in the electrical domain. This paper presents two different promising alternative approaches to vibration measurement, specifically in the field of fiber-optics [...] Read more.
New possibilities of vibration monitoring can be found in completely different physical approaches, where all measuring technology is currently based on sensors in the electrical domain. This paper presents two different promising alternative approaches to vibration measurement, specifically in the field of fiber-optics and pneumatic sensors. The proposed solution uses a Michelson fiber-optic interferometer designed without polarization fading and with operationally passive demodulation technique using three mutually phase-shifted optical outputs. Experimentally developed sensor systems for the registration of anthropogenic seismic phenomena were complemented by standard instrumentation for measuring seismicity used as a standard. The measurement was performed under simplified conditions using a calibrated stroke as a source of dynamic loading. In addition to alternative systems, the paper also presents the results of recalculation of the measured values in a time domain and basic relationships for the conversion to basic units derived from the SI (International System of Units) system and used internationally in the field of seismic engineering. The results presented demonstrate that even systems operating on a different physical principle have great potential to replace the existing seismic devices. The correlation coefficients for both sensory devices were high (above 0.9) and the average deviations from the measured values of the amplitude of the oscillation velocity did not exceed the value of 0.02, neither with the fiber-optic or pneumatic sensor. Full article
Show Figures

Figure 1

Article
Comparison of Pulse Wave Signal Monitoring Techniques with Different Fiber-Optic Interferometric Sensing Elements
Photonics 2021, 8(5), 142; https://doi.org/10.3390/photonics8050142 - 25 Apr 2021
Cited by 10 | Viewed by 928
Abstract
Pulse wave (PW) measurement is a highly prominent technique, used in biomedical diagnostics. Development of novel PW sensors with increased accuracy and reduced susceptibility to motion artifacts will pave the way to more advanced healthcare technologies. This paper reports on a comparison of [...] Read more.
Pulse wave (PW) measurement is a highly prominent technique, used in biomedical diagnostics. Development of novel PW sensors with increased accuracy and reduced susceptibility to motion artifacts will pave the way to more advanced healthcare technologies. This paper reports on a comparison of performance of fiber optic pulse wave sensors, based on Fabry–Perot interferometer, fiber Bragg grating, optical coherence tomography (OCT) and singlemode-multimode-singlemode intermodal interferometer. Their performance was tested in terms of signal to noise ratio, repeatability of demodulated signals and suitability of demodulated signals for extraction of information about direct and reflected waves. It was revealed that the OCT approach of PW monitoring provided the best demodulated signal quality and was most robust against motion artifacts. Advantages and drawbacks of all compared PW measurement approaches in terms of practical questions, such as multiplexing capabilities and abilities to be interrogated by portable hardware are discussed. Full article
Show Figures

Figure 1

Article
Akinetic Swept-Source Master–Slave-Enhanced Optical Coherence Tomography
Photonics 2021, 8(5), 141; https://doi.org/10.3390/photonics8050141 - 24 Apr 2021
Cited by 1 | Viewed by 1056
Abstract
This paper presents a different approach for processing the signal from interferometers driven by swept sources that exhibit non-linear tuning during stable time intervals. Such sources are, for example, those commercialised by Insight, which are electrically tunable and akinetic. These Insight sources use [...] Read more.
This paper presents a different approach for processing the signal from interferometers driven by swept sources that exhibit non-linear tuning during stable time intervals. Such sources are, for example, those commercialised by Insight, which are electrically tunable and akinetic. These Insight sources use a calibration procedure to skip frequencies already included in a spectral sweep, i.e., a process of “clearing the spectrum”. For the first time, the suitability of the Master–Slave (MS) procedure is evaluated as an alternative to the conventional calibration procedure for such sources. Here, the MS process is applied to the intact, raw interferogram spectrum delivered by an optical coherence tomography (OCT) system. Two modalities are investigated to implement the MS processing, based on (i) digital generation of the Master signals using the OCT interferometer and (ii) down-conversion using a second interferometer driven by the same swept source. The latter allows near-coherence-limited operation at a large axial range (>80 mm), without the need for a high sampling rate digitiser card to cope with the large frequency spectrum generated, which can exceed several GHz. In both cases, the depth information is recovered with some limitations as described in the text. Full article
Show Figures

Figure 1

Communication
Glycerol–Water Solution-Assisted Mach–Zehnder Temperature Sensor in Specialty Fiber with Two Cores and One Channel
Photonics 2021, 8(4), 103; https://doi.org/10.3390/photonics8040103 - 02 Apr 2021
Cited by 2 | Viewed by 647
Abstract
In this paper, we propose an in-fiber Mach–Zehnder temperature sensor based on a dual-core fiber with an eccentric core and a central core. The latter one is beside a fluidic channel embedded in the fiber. The effective refractive index of the guided mode [...] Read more.
In this paper, we propose an in-fiber Mach–Zehnder temperature sensor based on a dual-core fiber with an eccentric core and a central core. The latter one is beside a fluidic channel embedded in the fiber. The effective refractive index of the guided mode in the central core could be influenced by the glycerol–water solution filled in the fluidic channel. Thus, the transmitted spectrum of the sensor is shifted as a function of temperature. By monitoring the selected spectral dip shifts, an experimental sensitivity of 2.77 nm/°C is obtained in the range of 25 to 40 °C for a solution length of 15 cm. To further improve the temperature sensitivity, the solution length is increased up to 29.5 cm, and a higher sensitivity of 5.69 nm/°C is achieved in the same temperature range. The experimental results agree well with the theoretical ones. The proposed sensor has good robustness and stability, which makes it promising for applications of high precision temperature monitoring. Full article
Show Figures

Figure 1

Article
Giant Displacement Sensitivity Using Push-Pull Method in Interferometry
Photonics 2021, 8(1), 23; https://doi.org/10.3390/photonics8010023 - 19 Jan 2021
Cited by 4 | Viewed by 1320
Abstract
We present a giant sensitivity displacement sensor combining the push-pull method and enhanced Vernier effect. The displacement sensor consists in two interferometers that are composed by two cleaved standard optical fibers coupled by a 3 dB coupler and combined with a double-sided mirror. [...] Read more.
We present a giant sensitivity displacement sensor combining the push-pull method and enhanced Vernier effect. The displacement sensor consists in two interferometers that are composed by two cleaved standard optical fibers coupled by a 3 dB coupler and combined with a double-sided mirror. The push pull-method is applied to the mirror creating a symmetrical change to the length of each interferometer. Furthermore, we demonstrate that the Vernier effect has a maximum sensitivity of two-fold that obtained with a single interferometer. The combination of the push-pull method and the Vernier effect in the displacement sensors allows a sensitivity of 60 ± 1 nm/μm when compared with a single interferometer working in the same free spectral range. In addition, exploring the maximum performance of the displacement sensors, a sensitivity of 254 ± 6 nm/μm is achieved, presenting a M-factor of 1071 and MVernier of 1.9 corresponding to a resolution of 79 pm. This new solution allows the implementation of giant-sensitive displacement measurement for a wide range of applications. Full article
Show Figures

Figure 1

Communication
Salinity Sensing Characteristics Based on Optical Microfiber Coupler Interferometer
Photonics 2020, 7(3), 77; https://doi.org/10.3390/photonics7030077 - 21 Sep 2020
Cited by 9 | Viewed by 1100
Abstract
In this paper, we report a novel and compact sensor based on an optic microfiber coupler interferometer (OMCI) for seawater salinity application. The OMCI device is fabricated by connecting Faraday rotating mirrors to the two out-ports of the microfiber coupler, respectively. The sensor [...] Read more.
In this paper, we report a novel and compact sensor based on an optic microfiber coupler interferometer (OMCI) for seawater salinity application. The OMCI device is fabricated by connecting Faraday rotating mirrors to the two out-ports of the microfiber coupler, respectively. The sensor signal processing is based on a wavelength demodulation technique. We theoretically analyze the sensing characteristics with different device structure parameters. Besides, the results show that the date reading error decreases with the thinner waist region and longer arm difference. Through the experiment, the reflection spectra red-shifted as the sea water salinity increased; the highest response sensitivity of the OMCI salinity sensor reached 303.7 pm/‰ for a range of 16.6–23.8‰, and the resolution was less than 0.03‰. This study provides a new technical solution for the development of practical optical fiber seawater salinity sensors. Full article
Show Figures

Graphical abstract

Article
Liquid-Filled Highly Asymmetric Photonic Crystal Fiber Sagnac Interferometer Temperature Sensor
Photonics 2020, 7(2), 33; https://doi.org/10.3390/photonics7020033 - 19 May 2020
Cited by 8 | Viewed by 1241
Abstract
In this paper, we theoretically designed and numerically studied a high-resolution and ultrasensitive photonic crystal fiber temperature sensor by selective filling of a liquid with high thermo-optic coefficient in one of the airholes of the fiber. The finite element method was utilized to [...] Read more.
In this paper, we theoretically designed and numerically studied a high-resolution and ultrasensitive photonic crystal fiber temperature sensor by selective filling of a liquid with high thermo-optic coefficient in one of the airholes of the fiber. The finite element method was utilized to study the propagation characteristics and the modal birefringence of the fiber under different ambient temperatures. A large base birefringence value of 7.7 × 10−4 as well as a large birefringence sensitivity of almost 29% to a 10 °C temperature variation was achieved for the optimized fiber design with liquid chloroform between 15 °C and 35 °C. We also studied the performance of the proposed optical fiber in a temperature sensing Sagnac interferometer. An average linear temperature sensitivity of 17.53 nm/°C with an average resolution of 5.7 × 10−4 °C was achieved over a temperature range of 20 °C (15 °C to 35 °C). Full article
Show Figures

Figure 1

Review

Jump to: Editorial, Research

Review
Miniaturized Interferometric Sensors with Spectral Tunability for Optical Fiber Technology—A Comparison of Size Requirements, Performance, and New Concepts
Photonics 2021, 8(8), 332; https://doi.org/10.3390/photonics8080332 - 13 Aug 2021
Cited by 1 | Viewed by 827
Abstract
Optical interferometric sensors have acquired significant importance in metrology and information technology, especially in terms of their potential application in launching size, selectivity, sensitivity, resolution, spectral tuning ranges, efficiency, and cost. However, these demands are often contradictory and counteract one another, and are [...] Read more.
Optical interferometric sensors have acquired significant importance in metrology and information technology, especially in terms of their potential application in launching size, selectivity, sensitivity, resolution, spectral tuning ranges, efficiency, and cost. However, these demands are often contradictory and counteract one another, and are thus difficult to simultaneously fulfill during their interaction. This review focuses on a detailed comparison of seven different strongly miniaturized sensor concepts investigating the limits of these demands. For the visible and near-infrared spectral range, seven optical sensors were reviewed based on the following methodologies: classical optical transmission and reflection gratings, arrayed waveguide gratings, static Fabry–Pérot (FP) filter arrays, MEMS tunable FP interferometers, MEMS tunable photonic crystals, plasmonic filters, and fiber tip sensors. The comparison between the selected concepts concentrates on (i) the minimum space required for a particular spectral range, (ii) resolution, (iii) the integration in optical fiber technology, (iv) tunability to save space, (v) efficiency in using available light, (vi) multiplexing, (vii) miniaturization limits, and (viii) the potential of nanoimprint for cost reduction. Technologies for enhancing efficiency to obtain more available light and their applicability to the different methodologies were studied. Full article
Show Figures

Figure 1

Back to TopTop