Gravitational Wave Research Group Projects

Gravitational waves are ripples of space and time created by violent events in the Universe such as mergers of two black holes or core-collapse of massive stars at supernovae. Their existence was first predicted by Einstein's general theory of relativity. Gravitational waves will represent a completely new spectrum in astronomy and its detection will revolutionize our understanding of how space and time behave in violent events. The ultimate direct detections of gravitational waves are confidently expected in the coming decade, as a result of upgrades to current gravitational-wave detectors. Currently, there is a worldwide effort to build a km scale southern hemisphere gravitational wave detector at Gingin, Western Australia.

The development of advanced techniques to improve the sensitivity of gravitational wave detectors leads to exciting new physics phenomena and techniques that may have application beyond gravitational wave detectors. Our project covers a range of projects from vibration isolation and control, gravitational wave data analysis, and optical cavity experiment in both large and small scale.

Research Projects

  1. Using Light to Control Parametric Instability
  2. Supervisors: Chunnong Zhao, Li Ju and David Blair

    High optical power gravitational wave detectors are likely to suffer parametric instability due to the resonant interaction between the cavity optical modes and the high Q acoustic modes of the test mass mirrors. This instability can be suppressed by feeding back optical signals into the cavities. This project will investigate this idea of optical feedback control in a small scale experiment in the optical lab at physics on campus. The research result will be in conjunction with PhD students at the Gingin High Optical power Facility.

    Currently an optical cavity with an inside mechanical resonator has been frequency locked to the laser and 3-mode parametric interactions was observed. We expect to first observe the 3-mode parametric instability on the small scale experiment at UWA lab. Then we will setup an optical system to destructively interfere with the field inside the cavity to suppress the instability. This will be achieved by reflect the cavity transmitted beam back into the cavity after frequency shifting and phase masking. The reflected beam needs to be phase locked to the cavity transmission to maintain correct phase to destructively interfere with the beam inside cavity generated by the parametric process. The hardware particular for this experiment is ready.

  3. Opto-Acoustic Parametric Amplifier
  4. Supervisors: Chunnong Zhao, Li Ju and David Blair

    The OAPA is a new invention that has come out of our gravitational wave research. It utilises 3-mode parametric interactions in an optical cavity with three high quality factor resonant modes, (two optical, and one acoustic). The device enables very strong opto-acoustic coupling. This in turn enables unprecedented new technologies based on the ability to directly amplify or suppress acoustic vibrations with light. We can obtain very large positive or negative acoustic gain, and ultrasensitive measurements of vibration (acoustic signal transduction).

    To realize practical small scale devices requires specially designed mm-scale silicon resonators with high optical reflectivity. These have been designed and manufactured, and are ready for testing. The resonators form the end mirror of very high finesse optical cavity that is especially designed to support two optical modes at appropriate frequencies. This project will integrate the resonator to the optical cavity to create the first practical OAPA device and to characterize its performance. This very exciting project has the potential of creating very sensitive precision measurement devices and will pave the way towards cooling mm-scale objects to the quantum ground state and the creation of quantum memory devices.

  5. Double optical springs: towards measurements below the standard quantum limit.
  6. Supervisors: Chunnong Zhao, Li Ju and David Blair

    Optical springs are created by radiation pressure forces in optical cavities. Such springs modify both the mechanical frequency and the damping of suspended mirrors in optical cavities. Using two optical frequencies, it is possible to create a double optical spring in which the mechanical response of a mirror responds to weak forces as if it was nearly massless. This scheme has the potential of measuring macroscopic objects with resolution better than the ¡°standard quantum limit¡± predicted by naive application of quantum mechanics. This offers a new technique for improving gravitational wave detectors as well as allowing a range of new experiments in quantum experiments.

    This project aims to experimentally demonstrate that the double optical springs can be tuned to modify the mechanical resonator¡¯s response to weak forces so that the effective mass is much less than its actual mass. The experiment involves locking two laser beams with tunable frequency difference to an optical cavity. By tuning the frequency difference and the individual beam intensity we should be able to tune the double optical spring effect on the mechanical resonator, that is, one of the end mirrors of the cavity. The experiment will be conducted in the gravity wave group optics lab in UWA.

  7. Optical Rods and Bars
  8. Supervisors: Chunnong Zhao, Li Ju and David Blair

    It has recently been shown that radiation pressure can be used to create stable rigid optical ¡°rods¡± between suspended mirrors. The stiffness of the optical rod can exceed the stiffness of diamond. This technique offers far reaching possibilities from optically stabilised rigid structures in space to improved low frequency sensitivity in laser interferometers. This project will explore the new techniques. In UWA lab, table top cavities will be set up to test this idea in conjunction with the specially designed 80 meter high optical power cavity at Gingin with two special new mirrors for this experiment.

  9. Control system for the GW detector
  10. Supervisors: Chunnong Zhao, Li Ju and David Blair

    Distributed control systems

    This project is to create a generic distributed control platform using state-of-the-art digital control systems developed for gravitational wave detectors. The system uses a realtime Linux platform and PCIe bus distributed by optical fibres.

    Seismic feed-forward control for vibration isolation systems

    This project will develop a feed forward scheme for reducing the seismic noise in high performance vibration isolation systems for interferometer gravitational wave detectors. The project involves modelling and monitoring the seismic motion at the interferometer site, and its effects on the input stage of a multi-element vibration isolator. Modelling will determine the effectiveness of feed-forward control. The last part of the project will involve testing on the full scale system at Gingin gravitational wave laboratory.

  11. Design of Extremely Low Frequency Vibration Isolation Using Euler Springs
  12. Supervisors: Li Ju, David Blair and Chunnong Zhao

    Vertical vibration isolation at very low frequencies is the most challenging because spring systems have to store large amounts of gravitational potential energy, and end up being massive and having non-ideal performance. Some years ago the UWA group developed Euler springs that relies on the elastic buckling of a column. These springs avoid the problem of stored energy by exploiting the sudden transition between column stability and column buckling. During the past two years we have worked towards creating Euler tensile springs which can be used in an isolator structure called a Lacoste Linkage, which has already been demonstrated to achieve extremely low resonant frequencies. Successful designs for tensile Euler springs were demonstrated during 2011. We are now ready to integrate them into an already constructed Lacoste Linkage system.

    This project will utilise special Maraging steel springs fabricated by electric discharge machining and will integrate them into a Lacoste stage with view to creating a simple suspension capable of supporting 200kg mass with resonant frequency less than 50milliHertz. Such springs could have many uses in industrial and scientific vibration isolation.

  13. Detecting Gravitational Wave Events-data analysis.
  14. Supervisors: Linqing Wen, David Blair

    One area of our research aims at solving the most critical issues that the entire gravitational wave community is facing, that is, how to best detect a gravitational-wave event and identify its electromagnetic counterpart in a timely manner. Another area of our research is to explore the astrophysical properties of detectable gravitational wave sources.

    The data analysis approach is to participate directly in the on-going international frontier research in the gravitational-wave data analysis to discover and localize in real-time possibly the first gravitational-wave sources. One of our main aims is to provide the gravitational wave triggers to search for their electromagnetic (EM) counterparts using both radio and optical telescopes.

    In source modeling, we will use the theory of gravitation and data from electromagnetic observations to probe the astrophysical properties of GW sources.

    Students with proficiency in programming languages C and/MATLAB is a plus. Specific projects for this term are listed below. We expect the result of each of the projects will eventually lead to a publication in a high-impact journal.

    A. New fast and low-latency time domain search method

    Searches and localization of gravitational waves from coalescing binaries of neutron stars and black holes using our newly designed fast and low-latency time domain search method. The method will be applied to available data from a network of existing gravitational wave detectors around the world and will be applied to data from the upcoming advanced detectors. This project involves signal processing, and understanding of the properties of gravitational wave signals.

    B. Application of the graphics processing units (GPUs) to accelerate the search pipelines for gravitational waves.

    This project involves understanding of the architecture of the new generation of GPU cards (e.g., Fermi card) and design and test of the algorithms that best accelerate GW search pipelines.

    C. Probe of the system parameters of the gravitational-wave/X-ray source 4U 1820-30 residing in a globular cluster.