Surface plasmon resonance monitoring of temperature via phase measurement

The application of surface plasmon resonance to the monitoring of the temperature of a metal film and its environment is well-established. A new feature in our present experimental work is to carry out this monitoring via the measurement of the phase difference between a s and a p-polarized wave at different wavelengths, 632.8 nm and 1.15 μm, based on a technique established previously in the literature. By monitoring the change of this phase as a function of the film temperature, it is found that this approach leads to very sensitive measurements of temperature, in comparison with previous approaches in which reflectance was measured instead. Sensitivity is 0.027 K at incident wavelength of 632.8 nm and 0.1 K at incident wavelength of 1.15 μm. A simple model based on the temperature dependence of the optical constants of the metal is applied to simulate our measurements, and it is found that the general qualitative behavior and trend of the experimental results can be reasonably accounted for using such a model.