Attenuated total reflection measurements of superconductors: Addressing light-induced changes in superconductivity

We explore the behavior of superconducting materials using attenuated total reflection (ATR) measurements. Mid-infrared ATR measurements in the Kretchman and Otto configurations reveal the possibility of using ATR as an important tool in the study of superconductivity. ATR results as a function of temperature and thickness are presented and show that ATR can reveal valuable information on superconductors that may be difficult to obtain by other methods. In particular, we show that ATR is particularly suited for measuring the thickness of a light-induced resistive layer near the surface of a superconductor.