利用棱镜和金属膜组成Kretschmann模块,有机膜、金属膜和玻璃片组成衬底模块,当两个模块相互靠近时,就会构成以纳米空气间隙和有机膜为导波层的双面金属包覆波导结构。双面金属包覆波导结构中激发的导模共振的共振角与纳米空气间隙厚度之间呈线性关系,当选择其中一个模式的反射率曲线为探测信号时,就可通过测量其共振角的变化实现纳米空气间隙厚度的测量。数值模拟计算结果表明,这种结构可以实现0~100 nm范围内空气间隙厚度的测量,测量分辨率可达1 nm。

The Kretschmann module comprises a prism and metal film, and a substrate module comprises two metal films and a glass sheet. When the two modules are close to each other, a double-sided metal-cladding waveguide structure with a nano air gap and an organic film as the waveguide layer will be formed. The resonance angle of the guide mode resonance excited in the double-sided metal-cladding waveguide structure is linearly related to the thickness of the nano air gap. When the reflectivity curve of one of the modules is selected as the detection signal, the thickness of the nano air gap can be measured by measuring the change in the resonance angle. Numerical simulation calculation results show that this structure can measure the air gap in the range of 0--100 nm, and the measurement resolution can reach 1 nm.