Optical Trapping of Microdisks for Detection of Gravitational Waves*

We present an update on the Levitated Sensor Detector (LSD) project for detection of high frequency (10-100kHz) gravitational waves above the region previously probed by LIGO. Motivated sources of gravitational waves in this frequency range include superradiance from QCD axion clouds around spinning black holes. The experiment will make use of optically levitated flat dielectric micro-scale particles as force sensors with the advantage of reduced photon recoil heating. We therefore discuss initial experimental trapping and cooling results of high-aspect-ratio NaYF₄ hexagonal prisms. Additionally, we present information radiation patterns (IRPs) calculated from numerical simulations of light scattering for various shapes and sizes of particles, including hexagonal prisms, which are used to make improvements to position detection schemes in our levitated particle systems. Finally, we examine the experimental progress of the 1-meter LSD prototype that is in construction at Northwestern University.