Bonn 2025 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 26: Poster – Precision Measurement, Metrology, and Quantum Effects

Q 26.39: Poster

Dienstag, 11. März 2025, 14:00–16:00, Tent

Developing compact displacement sensors using Deep Frequency Modulation Interferometry (DFMI) — •Lea Carlotta Hügel, Leander Weickhardt, and Oliver Gerberding — Institut für Experimentalphysik, Universität Hamburg, 22761 Hamburg, Germany

Gravitational-wave detectors are currently, especially at low frequencies, limited by the noise of displacement sensors. Therefore, building high-precision displacement sensors is crucial for improving future gravitational wave detectors.

The displacement sensing technique, presented here, is called Deep Frequency Modulation Interferometry (DFMI). DFMI is a laser interferometry technique in which the frequency of the laser is rapidly modulated by a sine wave. DFMI is practical for more precise sensors because low-frequency signals are projected to higher frequencies, where they are not affected by higher readout noise in their original frequency region. To improve future implementations, identifying and evaluating the performance limits of DFMI, is the first step. An effect that can spoil the overall readout performance of DFM is the excitation of higher harmonics in the laser frequency modulation. This can e.g. be caused by non-linearities in the frequency actuation. DFMI is also limited by readout noise. By combining resonant enhancement and DFMI the overall sensitivity can be improved to a few fm/√Hz .

By looking at the latest status of our experiments, addressing these two problems, an interesting inside to the field of high precision displacement sensors can be gained.

Keywords: Gravitational wave detection; Displacement sensors