We present the characterisation of the most recent parametric transducers designed to enhance the Mario Schenberg Gravitational Wave Detector sensitivity. The transducer is composed of a microwave re-entrant cavity that attaches to the gravitational wave antenna via a rigid spring. It functions as a three-mode mass-spring system; motion of the spherical antenna couples to a 50 μm thick membrane, which converts its mechanical motion into a frequency shift of the cavity resonance. Through the optical spring effect, the microwave transducer frequency-displacement sensitivity was measured to be 726 MHz/μm at 4 K. The spherical antenna detection sensitivity is determined analytically using the transducer amplification gain and equivalent displacement noise in the test setup, which are 5.5 × 1011V/m and 1.8×10−19mHz−1, respectively.
@article{arxiv.1703.02179,
title = {Sensitivity Characterisation of a Parametric Transducer for Gravitational Wave Detection Through Optical Spring Effect},
author = {N. C. Carvalho and O. D. Aguiar and J. Bourhill and M. E. Tobar},
journal= {arXiv preprint arXiv:1703.02179},
year = {2017}
}