引力波及激光观测原理

GRAVITATIONAL WAVES AND THE PRINCIPLE OF LASER OBSERVATION

近期引力波话题火热,为使本科生对引力波有系统的了解,本文由爱因斯坦经典引力理论出发,考虑在远离场源的弱场近似,细致推导得到波速为光速、在空间上以横波形式传播的引力波的波动方程,并且指出引力波只存在两种独立的极化状态,即引力波两个独立的偏振方向。之后对激光观测引力波实验的理论进行合理性分析。得出装有法布里-珀罗腔结构的迈克耳孙干涉仪具备观测引力波能力的结论。

Gravitational waves become a hot issue recently.In order to make the undergraduates have systematic understanding of it,we review the derivation of gravitational waves in this paper.With Einstein classical gravitational theory,we obtain the wave equation from the weak-field approximation,and then we achieve the conclusion that the transverse waves of spatial strain travels at the speed of light.We point out that the gravitational waves exist only two independent polarized states,which means that the gravitational waves have two independent polarization directions.Furthermore,rationality about laser observation of the gravitational waves is analyzed both from theoretical and experimental aspects.Finally,we find a strategy to observe the gravitational waves by using the Michelson Interferometer with Fabry-Perot Cavity.