Submicron Fabrication in Optical Fibers for Sensing Applications

Abstract

Systems based on optical fibers have experienced significant progress and development since the 1970s. The revolution of optical communications has been the driving force behind the development of low-cost and low-loss optical fiber components. In parallel with optical communication systems, optical fibers are playing a strong role in many other applications such as sensing technologies. These sensing systems based on optical fibers offer considerable advantages over their traditional electrical counterparts, mainly in terms of sensitivity, multiplexing, cost and distributed architectures. Some specific applications, especially related to biological and environmental sensing, require the fabrication of precise sensing heads with feature sizes in the micrometer scale. In this work, new ways of fabricating micro structures for optical sensors are explored. In particular, focused ion beam milling is performed in single mode optical fibers, both on the lateral cladding material and directly on the fiber core. The flexibility of the milling technique allows fabricating a diverse set of structures and shapes with high precision. The current work focuses on fabricating long-period gratings on the fiber cladding, Fabry-Perot resonators on the fiber core tip along with a side access micro-channel (which enables interaction with surrounding environment), as well as diffraction gratings on the fiber core tip. Numerical simulations (both beam propagation method and finite-difference time-domain method) are used for finding the suitable dimensions of the desired structures. The fabricated sensing heads can be used for measuring chemical or physical parameters, such as salinity, bio-detection, or temperature. In addition to sensing, the fabricated diffraction gratings also find important applications in optical communications, in particular for spectral splitting in wavelength division multiplexing configurations.

Date of Award	Jul 2014
Original language	American English
Supervisor	Marcus Dahlem (Supervisor)