Department of Physics

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Jian Liu


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Jian Liu


Parametric instability in laser interferometric gravitational wave detectors


A century after the birth of General relativity, the sensitivity of laser interferometric gravitational waves detectors has been improved a lot. Before the fully operation of "advanced" detectors, we need to solve some problems, one of which is Parametric Instability (PI). PI is a phenomena where the optical modes in an interferometer are weakly scattered by thermally induced acoustic vibration of the mirrors, under certain conditions, the test mass acoustic modes can be amplified by the radiation pressure forces due to the beating of optical modes, then it can cause the amplitude if the mirror's acoustic mode to increase exponentially, thus cause the detector to stop operation.

My research is to investigate this phenomenon via desktop experiments. We use high power laser and high Q resonators to achieve higher parametric gain, then we will test some proposed methods of suppressing and controlling the PI.

Why my research is important

Gravitational wave, as one of the most significant prediction of General Relativity, offers the only way of probing the birth of the universe in the earliest moment of the Big Bang where time began. If PI is controlled, the detectors can run at the designed sensitivity and will enable us to detect the first gravitational wave signal years earlier and open a new window for humankind.


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Last updated:
Thursday, 17 April, 2014 9:11 AM