{'fraction_non_alphanumeric': 0.013109978150036417, 'fraction_numerical': 0.0014566642388929353, 'mean_word_length': 5.63768115942029, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Experimental validation of dual/modified dual arm locking for LISA

The laser frequency stabilization subsystem is one of the most significant parts within the interferometric measurement system of LISA. Arm locking as a proposed frequency stabilization technique synthesizes an adequately filtered linear combination of the interferometry signals as a frequency reference. Until now all the benchtop experiments on arm locking verified only the basic single arm locking configuration with unrealistic short signal travel times. At the University of Florida we developed the hardware-based University of Florida LISA Interferometer Simulator (UFLIS) to study and verify laser frequency noise reduction and suppression techniques under realistic LISA-like conditions. These conditions include the Doppler shifts between the spacecraft, LISA-like signal travel times, realistic laser frequency and timing noise. In this paper we will report about preliminary experiments on advanced arm locking schemes including dual arm locking and modified dual arm locking with realistic 33 s light travel times. In our experiments the implementation of a dual/modified dual arm locking sensor and controller is realized using several digital signal processing boards. We demonstrated the closed-loop stability of arm locking setup and measured the noise suppression in these experiments.