Date of Award

3-22-2019

Document Type

Thesis

Degree Name

Master of Science in Electrical Engineering

Department

Department of Electrical and Computer Engineering

First Advisor

Hengky Chandrahalim, PhD

Abstract

This thesis conducts research involving designing, fabricating, and testing optical fiber tip refractive index sensors. The fabrication process used for these sensors is a two-photon polymerization process utilizing a photo sensitive polymer. Unlike planar lithography, this fabrication process allows the creation of arbitrary shapes with a great degree of freedom. Three different fiber tip sensors were fabricated and tested. The first is a flat surfaced single cavity Fabry-Pérot interferometer (FPI) device, the second is a flat surfaced double cavity FPI device, and the final is a confocal surfaced double cavity FPI device. These sensors are tested for thermal radiation and volatile organic compounds (VOC) sensing. Thermal radiation sensing involves exposing the fiber tip device to temperatures ranging from room temperature up to 120oC. As the temperature increases, the fiber tip structure expands which changes its reflection spectrum. For VOC sensing each device was also exposed to isopropanol in gaseous form which results in a refractive index change. This change is also observed in the reflection spectrum. Lastly, research was conducted on thin dielectric reflective coatings for the purpose of increasing the reflectivity of the device surfaces resulting in a higher quality factor.

AFIT Designator

AFIT-ENG-MS-19-M-056

DTIC Accession Number

AD1076438

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