Ciencias Exactas y Ciencias de la Salud

The fast evolution of advanced optical fiber sensor technology leads to acquiring higher sensitivity and proficiency of the sensor. Recent developments of new types of optical fibers have magnificent designs and structures that enhance the flexibility and controllable setup for measuring several physical, chemical, and biological parameters. Particularly, the combination of photonic crystal fibers (PCFs) with plasmonic materials and sensing liquids or analytes performs an incredible operation in the field of sensing mechanisms. This thesis focuses on the different types of photonic crystal fibers with numerous sensing elements for measuring the magnetic field, refractive index, and temperature parameters. Both the simulation and experimental studies have been described. In the following sections, several types of optical fiber-based sensors are investigated. Firstly, a highly sensitive photonic crystal fiber based on plasmonic material and magnetic fluid (MF) for the simultaneous measurement of temperature and magnetic field sensor is investigated. The designed sensor is explored by tracing the different parameters such as birefringence, coupling length, power spectrum, and the peak wavelength of the transmission intensity. The magnetic field and temperature computation are attained simultaneously by examining the linear fitting curve and the movement of transmission peaks. The achieved sensitivity was 12 nm/Oe and 7.1 nm/oC for the magnetic field and temperature sensor, respectively. Secondly, we presented a simple highly sensitive sensor based on commercially available solid-core photonic crystal fiber (PCF) and surface plasmon resonance (SPR) for measuring the refractive index (RI) of analytes. The numerical simulation based on the finite element method (FEM) has been examined to compute the optical properties such as confinement loss, power spectrum, and transmission intensity of the sensor. The most sensitive and inert plasmonic materials (gold and silver) have been assumed to be coated inside the fiber with a range of analytes RI from 1.32 to 1.40. The performance of the proposed sensor has been evaluated by tracing several optical features like wavelength sensitivity, amplitude sensitivity, resolution of the sensor, and figure of merit. As a result, a comparative study between silver and gold elements has been carried out. Moreover, the effect of other structural parameters (air holes and the thickness of plasmonic layers) on the sensing performance has been considered. The maximum achieved wavelength sensitivity, amplitude sensitivity, power spectrum, and resolution is 1.15 μm/RIU, -32 RIU−1, 513 μm/RIU, and 0.0145 RIU−1, respectively. Thirdly, a simple magnetic field sensor based on a hexagonal photonic crystal fiber (PCF) and magnetic fluid (Fe3O4) has been examined. The simulation study has been carried out using the finite element method (FEM). The optical parameters such as birefringence, coupling length, power spectrum, and transmission intensity have been analyzed. The performance of the proposed sensor has been evaluated by tracing the optical features of wavelength sensitivity, linear regression, and resolution of the sensor. As a result, the higher sensitivity of the magnetic field sensor 0.1503 μm/Oe, 370 pm/Oe has been achieved with the resolution of 8.53 Oe.The designed sensing structure illustrates a simple shape, low cost, and high sensitivity device that could be a suitable candidate for sensing the magnetic field in man applications. Fourthly, we introduced a comprehensive study, based on both numerical and experimental analyses, of side polished (SP) single-mode fiber (SMF) to investigate their evanescent field interaction with air and liquid analytes. In particular, the finite element method (FEM) and the beam propagation method (BPM) are employed to predict the optical properties of the SP-SMF. An ad-hoc experimental setup has been designed and built to characterize the side-polished single-mode fiber when air, water, and isopropanol are set in the side-polished region. The performance in terms of effective refractive index and transmittance are reported to show how these SP-SMF can be efficiently used for calculating the liquid refractive index. The obtained sensitivity received as 1.23 V/RIU. The simulation and experimental results display the significant performance of the SP-SMF as a sensing element. Overall, the evaluation of different types of photonic crystal fibers with the linkage of plasmonic materials and sensing liquids shows great potential in the various applications of refractive index, temperature, and magnetic field sensing. The inspected structures and designs are presented with simplification, compactness, easy implementation, and low cost, which is expected to be a good foundation for the advancement of optical sensing devices. According to the analysis of results, these sensors are highly sensitive, have fast response, low loss, and have remarkable performance for the multifunctional parameters.

The attachment of polyethylene glycol (PEG) molecules, called PEGylation, can improve the therapeutic properties of proteins. The PEGylation product depends on the conditions under which the conjugation reaction takes place. PEGylation reactions often res

Ciencias Exactas y Ciencias de la Salud

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