Advancing mid-infrared microdisk laser emission with Tm:YAG

Mid-infrared microcavity lasers have important applications in biosensing, mid-infrared spectroscopy, and environmental monitoring. However, the low output power of existing mid-infrared microcavity lasers hinders their practical use. This drawback is attributed to the insufficient laser gain medium, which limits the development of mid-infrared whispering-gallery-mode (WGM) lasers. To address this issue, we have employed ion implantation-enhanced etching to fabricate Tm:YAG thin films as effective gain media for mid-infrared WGM lasers. The Tm:YAG thin film, with a thickness of 2 µm, exhibits excellent fluorescence characteristics. Subsequently, the Tm:YAG thin film is processed using focused ion beam to form microdisks with a diameter of 30 µm. Under 785 nm laser pumping, the maximum output power of the Tm:YAG microdisk at 2023.1 nm is 229 µW, with a slope efficiency of 2.9%. This work demonstrates the outstanding potential of Tm:YAG as a mid-infrared laser gain medium, providing a new option for the development of mid-infrared lasers.