8 research outputs found

    Surface Plasmon Resonance Sensor Interogation with Cladding Modes Excited by Tilted Fiber Bragg Grating

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    RÉSUMÉ Le but de ce projet est de developer de nouvelles configurations de capteurs Ă  rĂ©sonance de plasmons de surface basĂ©s sur les rĂ©seaux de Bragg. Il se concentre sur l’étude de quatre configurations novatrices de capteurs Ă  rĂ©sonances de plasmons et de leur application en mesure d’indice de rĂ©fraction environnant. PremiĂšrement, une nouvelle approche de mesure d’indice de rĂ©fraction utilisant un coupleur Ă  double gaine et un rĂ©seau de Bragg pour capturer les modes de gaine en rĂ©flexion est dĂ©montrĂ©e. Le spectre optique ainsi que la puissance des modes de gaines sont obtenus Ă  travers l’utilisation d’un coupleur Ă  fibre Ă  double gaine conçu sur mesure et connectĂ© Ă  un rĂ©seau de Bragg Ă  haute rĂ©flectivitĂ© Ă©crit dans une fibre photosensible standard lĂ©gĂšrement inclinĂ©e et gravĂ©e de façon Ă  la coupler au diamĂštre intĂ©rieur de la fibre Ă  double gaine. Ce dispositif est capable de capturer les modes de gaines autant d’ordres infĂ©rieurs que supĂ©rieurs en rĂ©flexion de maniĂšre simple et efficace. Il devient alors possible de dĂ©terminer l’indice de rĂ©fraction environnant avec une extrĂȘme sensibilitĂ© Ă  partir d’une perte de puissance mesurĂ©e de ≈ 91% de la puissance initiale permettant d’obtenir une rĂ©solution de 1.4333×10-5 unitĂ©s d’indice de rĂ©fraction (UIR) entre 1.37 et 1.45. Le dispositif permet donc une large bande d’opĂ©ration entre 1.30 et 1.45 UIR qui offre la possibilitĂ© de discriminer chacun des modes de gaine capturĂ©s. L’approche proposĂ©e peut ĂȘtre adaptĂ©e Ă  plusieurs autres types de capteurs de courbure, tempĂ©rature, indice de rĂ©fraction et d’onde Ă©vanescente. DeuxiĂšmement, une nouvelle approche de capteur Ă  rĂ©sonance de plasmons de surface Ă  fibre utilisant la configuration de coupleur Ă  double gaine dĂ©crite prĂ©cĂ©demment ainsi qu’un rĂ©seau de Bragg inclinĂ© et recouvert d’or est dĂ©montrĂ©e. Cette nouvelle approche d’interrogation basĂ©e sur le spectre de rĂ©flexion offre une amĂ©lioration de la bande d’opĂ©ration du dispositif en comparaison aux techniques prĂ©existantes. Le dispositif permet la dĂ©tection de rĂ©sonances de plasmons de surfaces dans le spectre de rĂ©flexion et de transmission, permettant aisĂ©ment une comparaison avec les techniques standards prĂ©existantes qui utilisent le spectre de transmission. Le capteur possĂšde aussi une large bande d’opĂ©ration allant de 1.335 Ă  1.432 UIR et une sensibilitĂ© de 510.5 nm/UIR.----------ABSTRACT The objective of this Thesis is to develop novel schemes in surface Plasmon resonance (SPR) sensing with Bragg gratings. The thesis focuses on research studies on the sensing characteristics of four novel configurations of SPR and surrounding refractive indices (SRI) sensors. Firstly, a novel SRI measurement scheme has been demonstrated using a double-clad fiber coupler (DCFC) and a fiber Bragg grating (FBG) to capture cladding modes in reflection. The optical spectra and power in the cladding modes are obtained through the use of a specially designed DCFC spliced to a highly reflective FBG written into slightly cladding-etched standard photosensitive single mode fiber to match the diameter to the inner cladding of the DCFC. The device is capable of capturing low and high order backward propagating cladding modes simply and efficiently. The device is capable of measuring the SRI with an extremely high sensitivity with a total power drop by ≈ 91% of its initial value and a resolution of 1.433×10-5 RIU between 1.37 and 1.45 RIU. The device provides a large SRI operating range from 1.30 to 1.45 RIU with sufficient discrimination for all individual captured cladding modes. The proposed scheme can be adapted to many different types of bend, temperature, refractive index and other evanescent wave based sensors. Secondly, a novel optical ïŹber SPR sensor scheme is demonstrated using reflected guided cladding modes captured by the above mentioned DCFC, and excited in a gold coated fiber with a tilted Bragg grating (TFBG). This new interrogation approach which is based on the reflection spectrum provides an improvement in the operating range of the device over previous techniques. The device allows detection of SPR in the reflected spectrum and also in the transmitted spectrum as well, making it far easier in comparison with previous standard techniques which use the transmission spectrum. The sensor has a large operating range from 1.335 to 1.432 RIU, and a sensitivity of 510.5 nm/RIU. The device shows strong dependence on the polarization state of the guided core mode which can be used to turn the SPR on or off

    A novel refractive index sensor based on an induced micro-structure fiber

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    Harnessing the fiber fuse for sensing applications

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