Measuring the thickness of ultra-thin film layers using terahertz time-domain polarimetry (THz-TDP)

We present experimental results from the application of our new terahertz full-polarimetry instrument, to measuring the thickness of ultra-thin films in a multi-layer coating system. While the standard time-of-flight measurement is limited by the bandwidth of the THz pulse in the minimum thickness resolution of the film that can be resolved using a time-domain system, the new terahertz time-domain polarimetry (THz-TDP) instrument can extend this limit to a few micrometers. This unique ability to measure the thickness of ultra-thin films (approximately λ/1000) is due to the accuracy of THz-TDP to resolve the polarization direction of the THz field within 1 degrees.