I have been working on experimental gravitational wave research and precision measurements since my PhD started in 1995. My research impact is on studying and mitigating high optical power effects in laser interferometer gravitational wave detectors. One of the effects is the interaction between optical field and the test mass mirror acoustic mode induced instability, or three-mode parametric instability. In 2005, I led a team who accomplished a detailed modelling task to determine whether this triple-resonance phenomenon could be a problem for the Advanced LIGO laser interferometer gravitational wave detectors then being designed. We showed that the phenomenon would be a serious risk to Advanced LIGO if not controlled, because it would prevent the laser power levels from being raised high enough to achieve high sensitivity. We also proposed an effective control scheme by thermally tuning the mirror radius of curvature. At the beginning of Advanced LIGO commissioning, the parametric instability appeared as we predicted. Of greatest importance was the fact that the instability was controlled by thermal tuning.

In addition to predicting and solving the instability problems, I and colleagues have turned the phenomenon of three-mode opto-acoustic interaction into potentially useful applications. We showed that especially engineered small scale devices called Opto-Acoustic Parametric Ampliers can be created. Powered by laser light, the devices are predicted to enable milligram-scale mechanical resonators to be cooled to the quantum-ground state, allowing the creation of a new class of super-sensitive light-powered instruments able to measure radio waves, forces, masses and ultrasound with unprecedented precision. Using similar opto-acoustic interactions, we have designed and demonstrated optomechanical filters with 1000-times higher resolving power than can be achieved using optics alone. The latest invention to have come out of this research is opto-mechanical negative dispersion technology. This enables the creation of entirely novel devices that are able to
resonantly amplify a broad band of frequencies simultaneously by causing different frequencies of light to have different effective velocities. We proved theoretically that this optomechanical device can be inserted into Advanced LIGO type detectors to improve the high frequency sensitivity, which will help to explore the binary neutron star merger remnants at kHz frequency band and to constrain the equation of state of dense matter.