An optical temperature measurement method based on Magneto-optical Kerr Effect of metal nanofilms

Abstract

In this study, we demonstrate a novel magneto-optical thermometer using a Magneto-optical Kerr Effect (MOKE) system optimally configured with a photoelastic modulator (PEM) that combines the optical and pyro effects of magnetic metal nanofilms to detect transient surface temperatures with high sensitivity and temporal resolution. The temperature-induced Kerr signal of the metal nanofilms is finally transformed into the AC-DC harmonic ratio. By innovatively configuring the analyzer axis close to the extinction position, the signal gain of the harmonic ratio can be increased while reducing the background signal, thus significantly improving the SNR of the temperature measurement. This magneto-optical thermometer combines the high spatial and temporal resolution of MOKE to provide a possible method for non-invasive and fast temperature measurements on the micro- and nanometer scales, and is expected to be useful in temperature imaging applications in conjunction with optical imaging techniques.