254 research outputs found
Optic-Fiber Temperature Sensor
As an important parameter in industry, agriculture, biomedical, and aerospace, temperature possesses a significant position for the development of our society. Thus, it has become a hot point to develop novel sensors for temperature monitoring. Compared with traditional electronic sensors, optical fiber sensors break out for the compact structure, corrosion resistance, multiplex and remote sensing capability, cheap prices, and large transmission capacity. Especially the phase modulation type optical fiber sensors attract much attention for the fast and accurate measurement of the external parameters in a large dynamic measurement range. In this work, we review the optical fiber Mach-Zehnder interferometer (MZI) for temperature sensing which is widely used these years. The fundamental principles of MZI fiber sensors are proposed and discussed to further understand MZI. Different kind of structures for temperature sensing of recent years are summarized as several typical MZI categories and their advantages and disadvantages are indicated separately. Finally, we make a conclusion of the MZI temperature sensing and several methods typically to realize the MZI in practical application for the readers
Intensity-modulated abrupt tapered Fiber Mach-Zehnder Interferometer for the simultaneous sensing of temperature and curvature
AbstractAn abrupt tapered fiber In-Line Mach-Zehnder Interferometer sensor for simultaneous measurement of temperature and curvature is proposed and experimentally demonstrated. The sensor head is fabricated by arcing Corning SMF-28 using a commercial arc fusion splicer. The individual parameters discrimination was achieved by manipulating the unequal sensitivities of optical power to temperature and curvature obtained at two wavelengths within the sensing spectrum. The curvature and temperature sensitivities at λ1 (1537nm) and λ2 (1568.7nm) were found to be 11.8264dBm/m−1, 12.4885dBm/m−1 and 0.0829dBm/°C, 0.0833dBm/°C, respectively. The experimental results show unperturbed readings with rms deviation of ±0.1801m−1 and ±0.0826°C, for curvature and temperature measurements, respectively, through measurement of optical power response of the sensor. With this simultaneous sensing technique, the proposed sensor can be deployed for many field applications such as nondestructive structural health monitoring of civil infrastructure
Tapered optical fibre sensors: current trends and future perspectives
The development of reliable, affordable and efficient sensors is a key step in providing tools for efficient monitoring of critical environmental parameters. This review focuses on the use of tapered optical fibres as an environmental sensing platform. Tapered fibres allow access to the evanescent wave of the propagating mode, which can be exploited to facilitate chemical sensing by spectroscopic evaluation of the medium surrounding the optical fibre, by measurement of the refractive index of the medium, or by coupling to other waveguides formed of chemically sensitive materials. In addition, the reduced diameter of the tapered section of the optical fibre can offer benefits when measuring physical parameters such as strain and temperature. A review of the basic sensing platforms implemented using tapered optical fibres and their application for development of fibre-optic physical, chemical and bio-sensors is presented
In-line tapered fiber Mach-Zehnder interferometer for biosensing applications
Due to the advantages of compact size, light weight, immunity to electromagnetic
interference and remote sensing, optical fiber sensors have been studied extensively since
the 60s. In particular, interferometric Mach-Zehnder fiber sensors are favourable for their
flexibility and high sensitivity. The principle of operation for these sensors bases upon the
interference between the light propagation in the core mode and the excited cladding
modes. The work presented in this thesis focuses on the fabrication of tapered Mach-
Zehnder interferometer in a single-mode fiber and its applications in biosensing.
In this study, two kinds of tapered fiber Mach-Zehnder interferometer, either
symmetric or asymmetric, have been fabricated using fusion splicing technique. In both
cases, the effects of varying the waist diameter, separation distance between tapers, and
propagation direction are studied. The symmetrical tapered fiber Mach-Zehnder
interferometer has been explored for biosensing applications. Using the dipping layer-bylayer
method, multiple thin films have been deposited on the fiber structure for the detection
of streptavidin which is a common target material used to test the effectiveness of a
biosensor. The sensing mechanism here relies on the electrostatic attraction between
cationic and anionic materials, in which the cationic material used in this study is poly
(allylamin hidrocloride) (PAH). While, the anionic material adopted here is either SiOâ‚‚
core/Au shell nanoparticles or poly (sodium 4-styrenesulfonate) (PSS). For the best of our
knowledge, this is the first time the tapered fiber Mach-Zehnder interferometer is used for
streptavidin sensing by applying the layer-by-layer technique.
Two types of multilayered structure are fabricated on the tapered region of the fiber
interferometer. The first multilayered structure consists of SiOâ‚‚:Au nanoparticles, in which
the deposition of a monolayer of the PAH polymer and a monolayer of the negatively
charged SiOâ‚‚:Au NPs represents a single bilayer of (PAH/SiOâ‚‚:Au NPs). The second
multilayered structure bases on the deposition of PAH and PSS polymer. Following the
fabrication of the multilayered structures is the functionalization with biotin which is a
vitamin that possesses a strong binding ability with streptavidin so it functions as an
adhesive material to streptavidin. The sensing response of the sensors on detecting aqueous
solutions of streptavidin has been observed by measuring the shift in the wavelength of the
transmission spectrum of the tapered fiber interferometer. The effects of depositing
(PAH/SiOâ‚‚:Au NPs) and (PAH/PSS) films in multilayered structures, as well as the
influences of different device specifications are investigated
Highly compact vector bending sensor with microfiber-assisted Mach-Zehnder interferometer
A low-cost and highly compact fiber-optic component is proposed and experimentally demonstrated for vector bending sensing. A segment of microfiber tapered from standard single-mode fibers (SMFs) is spliced between two SMFs with pre-designed lateral offset to construct a sandwich type Mach-Zehnder interferometer of 243.32 ?m in length. Sensing performances of the proposed vector bending sensor is theoretically analyzed in detail. As the applied curvature increases from 0.3873 m-1 to 3.0 m-1, the transmission spectra of the proposed sensor show distinct linear wavelength shift sensitivities for different directions, the maximum of which is up to 3.419 nm/m-1. Besides, temperature test indicates that the proposed sensor possesses a low temperature cross sensitivity of 33.71 pm/°C, which ensures its applicability for practical uses in temperaturefluctuated environment. Hence, our proposed vector bending sensor possesses such desirable merits as high sensitivity, compact size, low thermal crosstalk, low cost and orientation-dependent spectral response
Dispersion tailoring in both integrated photonics and fiber-optic based devices
Tesis por compendio[EN] This Thesis focuses on the study, implementation and characterization of chromatic dispersion tailoring employing both optical fiber and photonic integrated waveguides. Chromatic dispersion causes that the different spectral components of an optical pulse travel at different velocities. This effect can be separated into two different fundamental contributions, material dispersion and waveguide dispersion. Chromatic dispersion can be tailored through the design of the structural parameters of the device in order to obtain specific characteristics in the resulting dispersion profile such as low values of dispersion and/or zero dispersion at a desired wavelength, for example. This approach is very useful in dispersion-dependent applications. In this PhD, we investigate chromatic dispersion tailoring in two different transmission mediums, photonic integrated waveguides and optical fiber.
In the first case, two different geometries of Silicon-on-Insulator (SOI) integrated waveguides, strip and slot, are considered. By varying structural parameters such as the cross-section, aspect ratio or fill factor, different chromatic dispersion profiles are obtained. In addition, the influence of the slot location is evaluated. This study is carried out using simulation software in order to obtain the effective refractive index profile as a function of wavelength, which is later differentiated to obtain the final dispersion values. Besides, chromatic dispersion in both waveguide geometries is experimentally measured using an interferometer technique.
In the second case, the chromatic dispersion present in a tapered fiber is studied. A tapered fiber consists of a narrow waist located between two transition regions and it allows the modification of the conventional propagation conditions due to the interference between the modes propagating through the waist. This interference between modes creates a transmission pattern which depends on the waist length and the effective refractive indexes of the modes travelling through the waist. By applying stress to the tapered fiber its interference pattern can be modified. Chromatic dispersion profile of tapered fibers is obtained, tailored and compared with the dispersion profile of conventional single-mode fibers.[ES] Esta Tesis se centra en el estudio, implementación y caracterización del control de la dispersión cromática empleando tanto fibra óptica como guÃas integradas fotónicas. La dispersión cromática provoca que las distintas componentes espectrales asociadas con el pulso óptico viajen a diferentes velocidades. Este efecto puede ser dividido en sus dos contribuciones fundamentales, la dispersión del material y la dispersión de la guÃa. La dispersión cromática puede ser controlada a través del diseño de los parámetros estructurales del dispositivo para poder obtener asà determinadas caracterÃsticas en el perfil de dispersión resultante como por ejemplo bajos valores o localización de la longitud de onda de dispersión cero en una longitud de onda deseada. Este método es muy útil en aplicaciones dependientes de la dispersión. En esta Tesis, investigamos el control de la dispersión cromática en dos medios de transmisión diferentes, las guÃas fotónicas integradas y la fibra óptica.
En el primer caso, se consideran dos geometrÃas diferentes de guÃas integradas en silicio, las guÃas convencionales y las guÃas ranuradas. Mediante la modificación de los parámetros estructurales como la sección transversal de la guÃa, su relación de aspecto o el factor de llenado, se obtienen diferentes perfiles de dispersión cromática. Además, se evalúa la influencia de la situación de la ranura. Mediante software de simulación, se obtiene el perfil de Ãndice de refracción efectivo en función de la longitud de onda, que posteriormente se deriva y se obtiene el valor de la dispersión. Asimismo, se mide experimentalmente la dispersión en ambas geometrÃas utilizando una técnica interferométrica.
En el segundo caso, se analiza la dispersión cromática que presenta una fibra de tipo taper. Esta geometrÃa consiste en una cintura estrecha situada entre dos regiones de transición y permite la modificación de las condiciones de propagación convencionales debido a la interferencia entre los modos que se propagan por la cintura, que crea un patrón de transmisión dependiente de la longitud de la cintura y de los Ãndices efectivos de los modos. Aplicando tensión sobre la fibra, su patrón de interferencia puede ser modificado. La dispersión cromática de las fibras taper se obtiene, se modifica y se compara con el perfil de dispersión de una fibra convencional.[CA] La tesi a exposar se centra en l'estudi, implementació i caracterització del control de la dispersió cromà tica empleant la fibra òptica i les guies integrades fotòniques. La dispersió cromà tica provoca que els distints components espectrals associats amb la pols òptica viatgen a diferents velocitats. Aquest pot dividir-se en les dos contribucions fonamentals corresponents: la dispersió del material i la dispersió de la guia. La dispersió cromà tica pot controlar-se a través del disseny dels parà metres estructurals del dispositiu per poder obtindre aixi determinades caracterÃstiques en el perfil de dispersió resultant, com per exemple, baixos valors o localizació de la longitud d'ona de dispersió zero a una longitud d'ona desitjada. No obstant això, aquest mètode és molt útil en aplicacions depenents de la dispersió. A més a més, investiguem el control de dispersió cromà tica en dos mitjans de transmissió diferents, les guies fotòniques integrades i la fibra òptica.
D'una banda, es consideren dos geometries diferents de guies integrades en silici, les guies convencionals i les ranurades. Mitjançant la modificació dels parà metres estructurals com la secció transversal de la guia, la relació d'apecte o el factor d'ompliment, obtenim diferents perfils de dispersió cromà tica. Fins i tot, s'avalua la influència de la situació de la ranura. Mitjançant el programari de simulació, obtenim el perfil d'Ãndex de refracció efectiu en funció de la longitud d'ona, que posteriorment es derivarà i s'obrindrà el valor de la dispersió. Tanmateix, es mesura experimentalment la dispersió en les dos geometries utilitzant una tècnica interferomètrica.
D'altra banda, analitzam la dispersió cromà tica que presenta una fibra de tipus taper. Aquesta consisteix en una cintura estreta situada entre dos regions de transició que, ens permet la modificació de les condicions de propagació convencional com a causa d'una interferència entre els modes que es propaguen per la cintura i els Ãndex efectius dels modes. Si apliquem tensió sobre la fibra, el seu patró d'interferència podria ser modificat. La dispersió d'una fibra cromà tica de les fibres taper s'obté, es modific i es compara amb el perfil de dispersió d'una fibra convencional.Mas Gómez, SM. (2015). Dispersion tailoring in both integrated photonics and fiber-optic based devices [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/54113TESISCompendi
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Ultrasensitive Refractive Index Sensor Based on Mach-Zehnder Interferometer and a 40 mu m Fiber
An ultra-high sensitivity refractive index (RI) sensor, based on an in-line fiber Mach-Zehnder interferometer (MZI) and utilizing a special 40 μm fiber which has been specifically designed for the purpose, supporting only the LP 01 and LP 11 modes propagating in the fiber, has been proposed and numerically demonstrated in this work. The all-fiber MZI, based on LP 01 and LP 11 mode interference, was fabricated by utilizing a special design with two gradually tapered joints at both sides of this multi-clad thin diameter fiber (TDF). When the TDF diameters varied from 40 μm to 5 μm, a sudden change in the direction of the wavelength shift in the transmission spectrum of the TDF-MZI devices was observed both in liquid RI and air relative humidity (RH) monitoring experiments, as the surrounding RI or RH was seen to increase monotonically. Ultra-high sensitivity values of 5942.8nm/RIU (1.335-1.342) and 21292.2nm/RIU (1.4000-1.4025) were obtained in the experiments carried out, through the use of a tapered TDF-MZI device with TDF diameters of ~5 μm and ~9 μm, respectively. The maximum RH sensitivity of 1.084nm/%RH was obtained by the use of the TDF-MZI device with a TDF diameter of ~12 μm. A compact all-fiber TDF-MZI sensor was thus created with an overall sensing length of <; 4mm, showing the advantages of high sensitivity, low loss, and flexibility in the tunable monitoring direction of the wavelength shift. This design is well suited to various applications, where the high sensitivity RI and RH measurements are required at precise locations
Optical fiber sensors by direct laser processing: a review
The consolidation of laser micro/nano processing technologies has led to a continuous increase in the complexity of optical fiber sensors. This new avenue offers novel possibilities for advanced sensing in a wide set of application sectors and, especially in the industrial and medical fields. In this review, the most important transducing structures carried out by laser processing in optical fiber are shown. The work covers different types of fiber Bragg gratings with an emphasis in the direct-write technique and their most interesting inscription configurations. Along with gratings, cladding waveguide structures in optical fibers have reached notable importance in the development of new optical fiber transducers. That is why a detailed study is made of the different laser inscription configurations that can be adopted, as well as their current applications. Microcavities manufactured in optical fibers can be used as both optical transducer and hybrid structure to reach advanced soft-matter optical sensing approaches based on optofluidic concepts. These in-fiber cavities manufactured by femtosecond laser irradiation followed by chemical etching are promising tools for biophotonic devices. Finally, the enhanced Rayleigh backscattering fibers by femtosecond laser dots inscription are also discussed, as a consequence of the new sensing possibilities they enableThis research was funded by the Ministerio de EconomÃa y Competitividad of Spain (TEC2016-76021-C2-2-R),
the FEDER/Ministerio de Ciencia, Innovación y Universidades and Agencia Estatal de Investigación (PID2019-
107270RB-C21), and the Ministerio de Educación, Cultura y Deporte of Spain (PhD grant FPU2018/02797)
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