Date of Award

6-26-2026

Date Published

July 2026

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Physics

Advisor(s)

Stefan Ballmer

Subject Categories

Physical Sciences and Mathematics | Physics

Abstract

Since the first detection of gravitational waves in 2015, the LIGO-Virgo-KAGRA collabo- ration has detected over 300 gravitational-wave events. Planned upgrades to each detector will further improve gravitational wave sensitivity limits, pushing the frontier of multi- messenger astronomy and paving the way for next-generation detectors, like Cosmic Ex- plorer and Einstein Telescope. Though many challenges to reach sensitivity goals are being addressed, there are still cru- cial aspects of the detectors that are poorly understood and will inhibit gravitational wave detection commissioners from bringing future detectors to their design sensitivity. In par- ticular, increased circulating arm power targets will exacerbate challenges relating to con- trolling the detector’s thermal state, which can degrade its performance. This makes up- coming observing runs important milestones in mitigating the detector’s performance degra- dation due to thermalization effects. Beyond thermal challenges, technical noise sources will begin to limit future detector sensitivities. Cosmic Explorer, in particular, sets new re- quirements on the input laser’s intensity and frequency noise, making the design of novel input optics and control schemes imperative. The lessons learned from challenges faced by current detectors motivate design choices for Cosmic Explorer’s optical layout. This thesis details efforts to understand how thermal effects impact high power interfer- ometers, and how those effects can be mitigated. It also highlights efforts to understand the impact of laser intensity noise at points of the interferometer and what inteferometer parameters can be inferred with that understanding. Finally, an overview is given outlin- ing design efforts for Cosmic Explorer’s recycling cavities using newly developed modeling tools and lessons learned from current detectors.

Access

Open Access

Included in

Physics Commons

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