Animation Example
SPR can be observed when p-polarized light travels through a high-index medium and reflects off of a thin metal layer which is next to a low-index medium (e.g., the model is Glass/Gold/Air). The incident angle is slightly higher than the critical angle of the system without the thin metal layer (Glass/Air). SPR is observed as a large change in reflectance as the incident angle increases slightly. The thickness of the metal layer must not be too small or too great; 50 nm of gold is nearly ideal.
SPR has many uses, one of which is the measurement of thin dielectric layers deposited on the metal layer. Below we show the reflectance as a layer of SiO2 is deposited on the the gold layer. Note that the angle of minimum reflectance varies by about 13 degrees as the SiO2 thickness varies from 0 to 30 nm.
