Hannover 2016 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 16: Precision Measurements and Metrology IV (with A)

Q 16.5: Talk

Tuesday, March 1, 2016, 12:00–12:15, a310

Initial measurements using the eLISA Phasemeter optical testbed — Germán Fernández Barranco, •Daniel Penkert, Thomas Schwarze, Oliver Gerberding, and Gerhard Heinzel — Max Planck Institute for Gravitational Physics, Callinstraße 38 30167 Hannover

The planned spaceborne gravitational wave detector eLISA will allow the detection of gravitational waves at frequencies between 0.1 mHz and 1 Hz. It uses high-precision heterodyne laser interferometry as the main measurement technology. A breadboard model of the interferometric phase readout system (phasemeter) was developed in the scope of an ESA technology development project. This project was completed successfully fulfilling all performance requirements in an electrical two-signal test. Here we present the planning and advances in the implementation of an optical testbed for the phasemeter as well as initial measurements. The testbed is based on an ultra-stable hexagonal optical bench. This bench allows the generation of three unequal heterodyne beatnotes, thus enabling us to probe the phasemeter for nonlinearities in an optical three-signal test. The final goal is to show a performance in the microcycle/sqrt(Hz) regime for the upper part of the eLISA measurement band (5 mHz to 1 Hz) with a dynamic range of 10 orders of magnitude using beatnotes between 5 and 25 MHz. The initial measurements presented here fulfill this requirement down to 500 mHz for beatnote frequencies below 10 MHz. Once performance over the full bandwidth is achieved, other components of the eLISA arm metrology chain (clock noise transfer and removal, inter-satellite ranging and communication) can be tested in this setup.