Gravitational wave detectors with broadband high frequency sensitivity

Michael A Page,David Mason,Yanbei Chen,Maxim Goryachev,David G Blair,Yiqiu Ma,Massimiliano Rossi,Albert Schliesser,Li Ju,Haixing Miao,Michael E Tobar,Chunnong Zhao,Carl D Blair

doi:10.1038/s42005-021-00526-2

Abstract

Gravitational waves from the neutron star coalescence GW170817 were observed from the inspiral, but not the high frequency postmerger nuclear matter motion. Optomechanical white light signal recycling has been proposed for achieving broadband sensitivity in gravitational wave detectors, but has been reliant on development of suitable ultra-low loss mechanical components. Here we show demonstrated optomechanical resonators that meet loss requirements for a white light signal recycling interferometer with strain sensitivity below 10−24 Hz−1/2 at a few kHz. Experimental data for two resonators are combined with analytic models of interferometers similar to LIGO to demonstrate enhancement across a broader band of frequencies versus dual-recycled Fabry-Perot Michelson detectors. Candidate resonators are a silicon nitride membrane acoustically isolated by a phononic crystal, and a single-crystal quartz acoustic cavity. Optical power requirements favour the membrane resonator, while thermal noise performance favours the quartz resonator. Both could be implemented as add-on components to existing detectors.

Highlights

Gravitational waves from the neutron star coalescence GW170817 were observed from the inspiral, but not the high frequency postmerger nuclear matter motion
In our white light signal recycling (WLSR) interferometer design we use the PNC resonator characterised by Mason, et al, who have maintained a ωm/(2π) = 1.135 MHz out-of-plane vibrational mode at Qm = 1.03 × 109 and T = 10 K for a 20 nm thick Si3N4 membrane shielded with an acoustic bandgap of 1.07–1.28 MHz26
The PNC resonator can be optomechanically coupled by using it in a “membrane-in-themiddle” (MIM) configuration as characterised by Thompson et al.[27]

Summary

Introduction

Gravitational waves from the neutron star coalescence GW170817 were observed from the inspiral, but not the high frequency postmerger nuclear matter motion. Optical power requirements favour the membrane resonator, while thermal noise performance favours the quartz resonator Both could be implemented as add-on components to existing detectors. Since the detection of gravitational waves (GW) from binary black holes and neutron stars[1,2,3,4], there is increasing interest in improving the sensitivity and bandwidth of detectors to allow better characterization of gravitational wave sources. Detectors such as the proposed Einstein Telescope[5] and Cosmic Explorer[6] aim for improved low frequency sensitivity to dramatically increase the number of observable cycles from compact binary coalescence events. Configurations based on detuning and strongly coupled signal recycling[12] can produce a broadband response at high frequency, but achieving target sensitivity h ~ 10−24 Hz1/2 still requires arm power levels an order of magnitude higher than the best attained to date

Methods

Results

Conclusion