FOI

During the semesters of Fall 2018-Spring 2020, I conducted independent research in Fiber Optic Interferometry (FOI) with John Markert, for which I received a research fellowship from UT. FOI is an experimental method that uses the interference pattern formed by the constructive and destructive nature of waves. The objective of the project was to compare the sensitivity of force and magnetic torque measurements and identify sensitive magnetometer using micro-oscillations. This project focused on the frequency of a cantilever, which is a microscopic structure held fixed at one end and is free to oscillate at the other. Over the course of this project, I created a research manual explaining the details of this experiment and adapted my Python skills to graphically analyze and apply Lorentzian fits to our data. These fits tell us how sensitive the cantilevers are, and a more sensitive cantilever will allow for a more precise collection of data and less error in future projects. 

I received a research fellowship from UT allowing me to work on this project for a year and a half. I revitalized this experiment after it had been dormant for many years specifically because I wanted to better understand the instrumentation side of LIGO (Laser Interferometer Gravitational-Wave Observatory) and LISA (Laser Interferometer Space Antenna). Also, I wrote a lab manual detailing the intricacies of the experiment for future researchers on this project. After seeing how much progress I made while working independently for a semester, my advisor added a graduate student to the project to accelerate the results. Our lab unfortunately had to shut down due to COVID-19. Despite this, our research was presented online at the 2020 American Physical Society Conference.

           We report the design, construction, and use of a fiber-optic interferometer system with variable applied dc and ac magnetic field and magnetic field gradients for the characterization of micro-magnets on oscillators. The system has measure calibrated and displacements to determine resonant frequencies (~1-800 kHz), quality factors (~100-8000), amplitudes, and spring constants (~0.01 N/m) of resonances. Thermal-noise-driven data determined spring constants. The driven response to ac magnetic field gradients (amplitudes ~3-30 *10^-5 T/m) provided a direct measurement of magnetic moments: e.g., for a ~7 +/- 1 micrometer radius permalloy sphere, we measure a magnetic moment of 1.37 +/- .03 *10^-8 J/T, in agreement with the expected saturation moment of ~2 +/- 1 *10^-8 J/T. Characterization of these micro-magnets supports our nuclear magnetic resonance force microscopy (NMRFM) studies. In addition to NMRFM, other ongoing work involving fiber-optic interferometry includes its use in integrated, narrow (~0.2-2 mm phi) oscillator-fiber sensors for placement in thin channels (e.g., for fast, local quench detection) and its use in a fast-response pressure sensor for operation under extreme (jet/rocket) conditions. (See Presentation Below)