Laser Interferometry R&D

Studying and validating LISA metrology and going beyond LISA

LISA Test Bed

The LISA Test Bed, developed within the Precision Interferometry and Fundamental Interactions department, provides an integrated laboratory facility for studying and validating the metrology underpinning LISA.

Detailed schematic showing laser configurations, oscillators, and phase measurement components. — Experimental Model of the LISA Interferometry Benchtop at the University of Florida. The arrangement of the laser phase sources, EPD units, phase-lock loops, PD signal beatnotes, and PM measurements which are used to emulate the LISA-IMS in our experiments are presented. The measured s_sr signals are used to form the TDI combinations.

from arxiv:1205.1934

Experimental Model of the LISA Interferometry Benchtop at the University of Florida. The arrangement of the laser phase sources, EPD units, phase-lock loops, PD signal beatnotes, and PM measurements which are used to emulate the LISA-IMS in our experiments are presented. The measured s_sr signals are used to form the TDI combinations.

from arxiv:1205.1934

A central element of this activity is the construction of a dedicated optics laboratory in which laser systems, optical benches, and electronic signal-generation units are used to create representative LISA interferometric signals directly on the ground. By reproducing controlled optical phase evolution, inter-spacecraft–like delays, and relevant noise processes, the facility enables detailed investigations of the measurement chain in a fully configurable and repeatable environment.

The test bed will bring together

laser sources,
interferometric paths,
phasemeter readout, and
time-delay interferometry (TDI)

into a single platform. This will allow us to generate, manipulate, and analyse LISA-like signals entirely in the laboratory, supporting studies of phasemeter performance, calibration techniques, synchronization schemes, and the behaviour of analysis algorithms when confronted with realistic signal conditions.

The facility also provides a framework for injecting simulated signals—such as gravitational-wave waveforms or specific noise contributions—directly into the optical or electronic chain, enabling controlled hardware-in-the-loop investigations.

Over the next years, the LISA Test Bed will evolve into a comprehensive hardware-in-the-loop environment tightly connected to mission-level data-processing pipelines. Laboratory-generated optical and electronic signals will be processed using the same TDI and reconstruction methods developed for LISA, allowing systematic assessment of robustness, the identification of nonidealities, and exploration of mitigation strategies.

Planned extensions include the implementation of multiple optical links, paving the way toward realistic emulation of the full LISA constellation.

Beyond LISA Group

The Beyond LISA Group, part of the Precision Interferometry and Fundamental Interactions department, is dedicated to the development of technologies, architectures, and system-level models for future space-based gravitational-wave observatories operating beyond the LISA band.

The group focuses on mission concepts in both the decihertz and microhertz regimes, with an emphasis on identifying technically viable configurations, understanding metrology requirements, and exploring pathways to extend interferometric capabilities to new frequency ranges.

Current work includes

modeling noise sources and sensitivity limits for long-baseline interferometers,
evaluating orbital configurations and constellation geometries, and
studying trade-offs in laser power, telescope size, and interferometric architecture.

The group also investigates requirements on free-fall performance, spacecraft control, and measurement synchronization, with the goal of establishing realistic performance budgets for next-generation missions.

At the institute, we aim to build a coherent framework for assessing mission feasibility across the spectral range, and to provide the community with quantitative tools for comparing concepts. This includes the development of simulation pipelines, performance models, and system-level studies that inform design decisions within international working groups.

In the coming years, the group will support the consolidation of a community-wide strategy for Europe’s next space-based gravitational-wave mission and will deepen its involvement in mission-design and metrology studies. The group also contributes to the GW Space 2050 working activities, providing system modeling and instrumental input for future mission definitions.