Joseph Hocking
- Dr, Alumni
- Terra 15
The current generation of gravitational wave detectors are limited in their bandwidth as high frequency gravitational waves cannot benefit from the high signal gain that long detector arms allow for in low frequency signals. Phrased in different terms, the fixed nature of the gain-bandwidth product of the detector means that having the high gain necessary for the detection of weak signals means we lose out on high frequency signals. However, we can take advantage of quantum effects to break this fixed product and allow for both high gain and high bandwidth through a proposed white-light signal recycling cavity (WLSRC). This recycling cavity would take in the detector output, apply a frequency dependent phase correction, ensuring that the accumulated phase is zero for a large range of frequencies, and then feed it back into the detector to allow for amplification of the high frequency gravitational wave signal. My work is focused on the characterization of materials to perform this frequency dependent phase correction. When the original idea was proposed, it was thought that atomic media would be the best route forward, however it was shown later that this would not be possible without causing the media to begin lasing. Instead optomechanical resonators are currently being explored, with my work on the bulk acoustic wave (BAW) resonator being a possibility. Like with everything, there is a trade-off. We require very ideal thermal properties (ie. non-absorbent to 1064nm, and low thermal distortion) and the relatively high mass of the BAW assists with this. However, also due to the high-mass, it becomes very hard to excite the mechanical resonance of the BAW with radiation pressure, thus the goal of this research project is to fine tune the material propeties of the BAW resonator to allow for optimum phase correction with minimal noise introduction.
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