Low absorption metrology of thin film optical components for high power continuous wave lasers

The increase of continuous wave laser power is an important topic in various industrial and defense applications. One of the important limitation is due to optical coatings. In order to study this absorption, it is of prime importance to measure and determine the origin of this absorption. We have developed a LIT system (LIT) to perform low-absorption measurement at 1.07 μm. A multipass setup was realized and calibrated with a sensitivity of a few ppm and a ten times better accuracy is demonstrated. Then, this instrument was used to study single layers made with different materials and deposited by PIAD and multilayer components.