参量变化对长程表面等离子体波特性的影响

为了掌握长程表面等离子体波的共振角度、共振峰半峰全宽以及衰减峰深度等重要特性，采用棱镜耦合激发介质-金属薄膜-介质对称结构中的长程表面等离子体波，研究了金属膜材料、厚度、介质折射率及介质厚度等参量变化时对长程表面等离子体波特性的影响。结果表明，实验中激发的长程表面等离子体波的衰减峰半峰全宽比传统的窄1~2个数量级；当介质膜厚度为500nm和1300nm时，激发的表面等离子体波的衰减深度只有薄膜厚度为700nm和1000nm时的1/2左右；随着介质膜厚度的增加，半峰全宽减小，金属膜越薄，衰减深度越深，衰减峰的半峰全宽值越小；介质膜折射率的改变对于半峰全宽的影响不明显；金属膜参量的变化将改变共振峰的位置。该研究为长程表面等离子体波的激发及应用于传感领域提供了有效依据，有利于其在波导和生物传感等方面的应用。

Influence of parameters change on the characteristics of long-range surface plasma wave

In order to acquire the characteristics of long-range surface plasma wave, such as the resonance angle, full width at half maximum of resonance peak and depth of attenuation peak, a prism coupling method was used to excite the long-range plasma surface wave of media-metal film-media symmetrical structure.The influences of the changes of material film material, metal film thickness, medium refractive index, medium thickness and other parameters on the characteristics of long-range surface plasma wave were studied.The results show that, the full width at half maximum of the attenuation peak of long-range surface plasma wave is narrower about 1 or 2 orders of magnitude than that of traditional surface plasma wave.When the dielectric film thickness is 500nm and 1300nm, the attenuation depth of plasma surface wave is only about 1/2 of those of dielectric film thickness 700nm and 1000nm.The full width at half maximum decreases with the increasing of dielectric film thickness.The thinner metal film is, the deeper attenuation depth is, the smaller full width at half maximum of attenuation peak is.The changes of medium refractive index has no obvious influence on full width at half maximum.The various metal film parameters will change the position of resonance peak.The study provides the effective basis for the application of long-range surface plasma wave in sensing, waveguide, and biosensors field.