PhD candidate Jessica Ma was recently awarded an APL Graduate Fellowship. Her proposed project is about the characterization of extremely low-level optical absorption and scattering in crystalline and amorphous materials for high-energy laser (HEL) applications.
Jessica states in her project proposal:
When people read this project title, they would think that low-level optical absorption and scattering are generally derisible for many optical applications. However, for this project, such low-level is detrimental for the future generation of HEL. For the laser materials (i.e.YAG, sapphire, fused silica) used in the current high energy lasers (i.e. laser window, gain medium, dome), at the operating wavelength near 1 micron, they all exhibit low-level absorption and scattering. These effects do not cause problems for the current generation of HEL since the operating power is relatively low (a few kW). Nevertheless, for the next generation of HEL (power up to MW), low-level absorption and scattering in these materials can cause significant problems such as thermal lensing and beam distortion, which can lead to a large power loss and laser damage. Therefore, it is important to study the mechanisms behind the weak absorption and scattering exist in different laser materials of interest at the operating wavelength. These mechanisms are likely to be linked with material physical properties but no comprehensive characterization on the mechanisms have been done to date.
Jessica’s goals for the project are to 1) design a sensitive absorption technique to measure the extremely weak absorption in different materials; 2) perform comprehensive material characterizations in order to obtain physical properties of each material; 3) work on model development to link the measured absorption and scattering data with material properties. Upon completion, Jessica plans to use the project for her thesis research.