作为光频段局域表面等离激元的低频对应物，人工局域表面等离激元因其深亚波长局域场增强和高Q值谐振的特点而受到广泛关注。微波等离激元谐振器是产生人工局域表面等离激元的典型器件，其特点是具有多重离散旋转对称性和镜面反射对称性。以往的研究提出了等效媒质法和等效色散法分析微波等离激元谐振器的模式响应，但这两种方法都未能充分考虑谐振器的几何对称性从而未能全面揭示其模式特性。本文针对谐振器的几何对称性提出了群表示论方法分析其模式响应。通过对称性分析，发现谐振器的几何对称性所构成的群的不可约表示数等于谐振器所能支持的人工局域表面等离激元模式的数目。以对称性构成C7v群的谐振器为例，C7v群的5个不可约表示数对应了5种人工局域表面等离激元模式，分别为零阶模式(也即磁偶极子)、偶极子、四极子、六极子和十四极子。受限于几何对称性，谐振器将不能支持更多阶的模式。为验证群表示论方法，设计了对称性构成C7v群的微波等离激元谐振器，全波仿真结果很好地证明了上述理论。本文提出的群表示论方法也可推广到其他频段如光频，因而具有广泛的适用性。

In this paper, we have proposed a metal-insulator-metal (MIM) pressure sensor which consists of two plasmonic waveguides and a double square ring resonator. The two square rings are connected via a rectangular patch located between the two of them. The surface plasmon polaritons (SPPs) can be transferred from a square ring to the other through this patch. The finite-difference time-domain method (FDTD) has been used to simulate the device. Applying a pressure on the structure, it deforms, and a red shift of 103 nm in the resonance wavelength has been calculated. The deformation is linearly proportional to the wavelength shift in a wide range of wavelength. The proposed optical plasmonic pressure sensor has a sensitivity of 16.5 nm/MPa which makes it very suitable for using in biological and biomedical engineering.