Phase noise contribution of EOMs and HF cables

Two key components of LISA's inter-spacecraft clock tone transfer chain are electro-optic modulators (EOMs) and high-frequency (HF) cable assemblies. At modulation frequencies of 2 GHz, we characterized the excess phase noise of these components in the LISA frequency range (0.1 mHz to 1 Hz). The upper phase noise limit was found to be almost an order of magnitude better than required. In addition, phase dependencies on temperature were determined. The measured coefficients are within a few milliradians per Kelvin and thereby negligible due to the specified on-board temperature stability