Tunable coherence laser interferometry: demonstrating 40dB of straylight suppression and compatibility with resonant optical cavities

Fuente: arXiv
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Hauptverfasser: Voigt, Daniel, Eggers, Leonie, Isleif, Katharina-Sophie, Koehlenbeck, Sina M., Ast, Melanie, Gerberding, Oliver
Format: Preprint
Veröffentlicht: 2025
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author Voigt, Daniel
Eggers, Leonie
Isleif, Katharina-Sophie
Koehlenbeck, Sina M.
Ast, Melanie
Gerberding, Oliver
author_facet Voigt, Daniel
Eggers, Leonie
Isleif, Katharina-Sophie
Koehlenbeck, Sina M.
Ast, Melanie
Gerberding, Oliver
contents A major limitation of laser interferometers using continuous wave lasers are parasitic light fields, such as ghost beams, scattered or stray light, which can cause non-linear noise. This is especially relevant for laser interferometric ground-based gravitational wave detectors. Increasing their sensitivity, particularly at frequencies below 10 Hz, is threatened by the influence of parasitic photons. These can up-convert low-frequency disturbances into phase and amplitude noise inside the relevant measurement band. By artificially tuning the coherence of the lasers, using pseudo-random-noise (PRN) phase modulations, this influence of parasitic fields can be suppressed. As it relies on these fields traveling different paths, it does not sacrifice the coherence for the intentional interference. We demonstrate the feasibility of this technique experimentally, achieving noise suppression levels of 40 dB in a Michelson interferometer with an artificial coherence length below 30 cm. We probe how the suppression depends on the delay mismatch and length of the PRN sequence. We also prove that optical resonators can be operated in the presence of PRN modulation by measuring the behavior of a linear cavity with and without such a modulation. By matching the resonators round-trip length and the PRN sequence repetition length, the classic response is recovered.
format Preprint
id arxiv_https___arxiv_org_abs_2501_11528
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Tunable coherence laser interferometry: demonstrating 40dB of straylight suppression and compatibility with resonant optical cavities
Voigt, Daniel
Eggers, Leonie
Isleif, Katharina-Sophie
Koehlenbeck, Sina M.
Ast, Melanie
Gerberding, Oliver
Optics
Instrumentation and Methods for Astrophysics
General Relativity and Quantum Cosmology
Instrumentation and Detectors
A major limitation of laser interferometers using continuous wave lasers are parasitic light fields, such as ghost beams, scattered or stray light, which can cause non-linear noise. This is especially relevant for laser interferometric ground-based gravitational wave detectors. Increasing their sensitivity, particularly at frequencies below 10 Hz, is threatened by the influence of parasitic photons. These can up-convert low-frequency disturbances into phase and amplitude noise inside the relevant measurement band. By artificially tuning the coherence of the lasers, using pseudo-random-noise (PRN) phase modulations, this influence of parasitic fields can be suppressed. As it relies on these fields traveling different paths, it does not sacrifice the coherence for the intentional interference. We demonstrate the feasibility of this technique experimentally, achieving noise suppression levels of 40 dB in a Michelson interferometer with an artificial coherence length below 30 cm. We probe how the suppression depends on the delay mismatch and length of the PRN sequence. We also prove that optical resonators can be operated in the presence of PRN modulation by measuring the behavior of a linear cavity with and without such a modulation. By matching the resonators round-trip length and the PRN sequence repetition length, the classic response is recovered.
title Tunable coherence laser interferometry: demonstrating 40dB of straylight suppression and compatibility with resonant optical cavities
topic Optics
Instrumentation and Methods for Astrophysics
General Relativity and Quantum Cosmology
Instrumentation and Detectors
url https://arxiv.org/abs/2501.11528