Challenges and Opportunities of Direct In-Band Pumping for High-Power Ho:YAG Lasers

A direct in-band pumped Ho:YAG system has the potential to achieve high overall efficiency; however, it remains challenging to achieve high power output. This is due to the narrow absorption peak of Ho:YAG, which has a full width at half maximum (FWHM) of only 7nm, as well as the small absorption coefficient of the diode stack when operating at high driving current [10]. Additionally, this type of LD suffers from severe thermal issues and has not yet been fully developed, making it unsuitable and costly for use in high power laser systems.