FH Particle Physics Pizza seminar: Stray Light Challenges in LISA Interferometry

Monday 13 May 2024, 11:30 → 13:00 Europe/Berlin

SR 4 (DESY Hamburg)

Aaron Dean Spector (DESY), Claudia Seitz (DESY), Juergen Reuter (DESY)

The goal of the FH Particle Physics Pizza seminar is to foster discussion and exchange between the various FH physics groups at DESY. Specifically, we are trying to enhance the exchange between the experimental and theory community, with in-depth talks about a specific topic in a more informal setting. 
 

We will order pizza (vegetarian and meat options with cheese) to eat for lunch. In order to have a better estimate of how many people come, please click on the "Register" link below. 

 

Please register if you want to eat pizza, we will collect 7 Euros from every participant who registers. If you have any specific food requirements (vegan, gluten free, etc.) please let us know in advance and we will see what we can do. If a reference paper exists, we will link it from the page and encourage you to read it before the seminar. 

 

If you do not want pizza, you do not need to register, just join us in the seminar.

 

ZOOM connection

https://desy.zoom.us/j/62825129183?pwd=NDRuQTZBeFNKeWVnMzBzNkJIMm9IUT09
Meeting ID: 628 2512 9183
Passcode:  629967

11:30 → 12:10 Stray Light Challenges in LISA Interferometry: Sources, Dynamics, and Mitigation Strategies

In space-based gravitational wave observatories like LISA, achieving sub-picometer (urad) precision at frequencies below 1Hz is essential for detecting cosmic events such as black hole mergers, neutron star collisions, and galactic interactions. However, interferometric sensitivity is compromised by stray light—unwanted laser beams that propagate within the main interferometer and interact with other beams, forming competing interferometers. This interaction results in phase errors that can limit the urad precision. In this presentation, we categorize types of stray light, including ghost beams and fiber Rayleigh backscatter, and predict their impact on phase errors using the small-vector noise model. We emphasize the critical influence of stray light's amplitude and phase on phase errors and highlight the need for environmental stability, such as temperature and air density control, to mitigate these errors. We will present comparisons between simulation data and experimental data from the LISA backlink fiber, affected by fiber length noise due to fiber Rayleigh backscattering. Our findings demonstrate that environmental stabilization can significantly reduce phase errors. Additionally, we explore various mitigation strategies, including beam baffles, balanced detection, frequency shifting, digital interferometry, and optimizing interferometer designs through IfoCAD optical simulations. These strategies are designed to obstruct stray light beams from inducing phase errors on the photodiode, thus enhancing measurement precision crucial for LISA and advancing the sensitivity of gravitational wave detection and other high-precision experiments.

Speaker: Prof. Katharina-Sophie Isleif (HSU (Helmut-Schmidt-Universität), DESY)

20240513_LISAStrayLight_DESYFHseminar.pdf

12:30 → 12:50 Pizza