Enhanced detection of high frequency gravitational waves using optically diluted optomechanical filters

TL;DR

This paper models optomechanical filters using AlGaAs/GaAs materials to enhance high-frequency gravitational wave detection, achieving significant sensitivity improvements over current detectors.

Contribution

It introduces a detailed analysis of optomechanical filters for high-frequency GW detection, identifying optimal parameters for thermal noise suppression and sensitivity enhancement.

Findings

Achieves 8-fold strain sensitivity improvement at 2 kHz

Detection volume increases by a factor of 500

Identifies suitable resonator dimensions for low thermal noise

Abstract

Detections of gravitational waves (GW) in the frequency band 35 Hz to 500 Hz have led to the birth of GW astronomy. Expected signals above 500 Hz, such as the quasinormal modes of lower mass black holes and neutron star mergers signatures are currently not detectable due to increasing quantum shot noise at high frequencies. Squeezed vacuum injection has been shown to allow broadband sensitivity improvement, but this technique does not change the slope of the noise at high frequency. It has been shown that white light signal recycling using negative dispersion optomechanical filter cavities with strong optical dilution for thermal noise suppression can in principle allow broadband high frequency sensitivity improvement. Here we present detailed modelling of AlGaAs/GaAs optomechanical filters to identify the available parameter space in which such filters can achieve the low thermal noise required to allow useful sensitivity improvement at high frequency. Material losses, the resolved sideband condition and internal acoustic modes dictate the need for resonators substantially smaller than previously suggested. We identify suitable resonator dimensions and show that a 30 $\mu$m scale cat-flap resonator combined with optical squeezing allows 8 fold improvement of strain sensitivity at 2 kHz compared with Advanced LIGO. This corresponds to a detection volume increase of a factor of 500 for sources in this frequency range.