Optical springs to create macroscopic optical traps and negative inertia for gravitational wave detectors

Wright, Jennifer L. (2022) Optical springs to create macroscopic optical traps and negative inertia for gravitational wave detectors. PhD thesis, University of Glasgow.

Abstract

This thesis investigates the phenomena of negative inertia and optical traps, and endeavours to implement them in an interferometer system that is a prototype of a gravitational wave detector arm cavity and uses similar control techniques and apparatus. Chapter 1 discusses gravitational waves and how they are produced. It then moves onto the basic design of current gravitational wave detectors and the main noise sources that are required to be taken into account when engineering the detector. Lastly, it concludes by discussing future gravitational wave detector designs and how this work might inform these. In Chapter 2 the theoretical underpinnings of optical springs are discussed. The chapter moves on to discuss the quantum noise of an interferometer and how optical springs change this. An expression for the optical spring constant is given, and then the thesis discusses how the frequency dependence of this quantity complicates obtaining analytical expressions. A review of optical spring stability in a Fabry-Perot interferometer is then provided. Systems with multiple optical springs that would be interesting to investigate in the current work are discussed, then a justification is given for investigating these effects and optical springs in general, in the light of the current state of the field. The layout of the experimental apparatus is laid out in Chapter 3. There are two experimental cavities which share a common mirror, the central test mass (CTM), and two input lasers. The setup of the optical systems is discussed first, then the layout of the suspensions, then how the electronic control of the lasers and experimental cavities is achieved. Chapter 4 lays out the procedure for calibrating the experiment and carrying it out. The determination of the cavity circulating power is discussed mathematically. Then the setup of the cavity simulation, the experimental calibration of the two cavity measurement process, and finally the calibration of spring detuning in the main experimental cavity is described. Results of the main thesis experiments are discussed in Chapter 5. Measurements using simple optomechanical systems are discussed first, then more complex measurements are described. Finally, evidence for both negative inertia and trapping is discussed. The conclusion given in Chapter 6 sums up the tasks achieved in the thesis work and the limitations of the results obtained are discussed. Some suggestions for further work are given.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Subjects: Q Science > QC Physics
• Colleges/Schools: College of Science and Engineering > School of Physics and Astronomy
• Supervisor's Name: Hough, Prof. James and Strain, Prof. Ken
• Date of Award: 2022
• Depositing User: Theses Team
• Unique ID: glathesis:2022-83126
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 14 Sep 2022 11:33
• Last Modified: 14 Sep 2022 11:33
• Thesis DOI: 10.5525/gla.thesis.83126
• URI: https://theses.gla.ac.uk/id/eprint/83126