High-Power Q-Switched Near Infrared Cryogenic Lasers

• Main Authors: Ganija, Miftar, Boyd, Keiron, Munch, Jesper
• Format: Conference Proceeding
• Language: English
• Subjects: Biomedical optical imaging; Cooling; Cryogenics; Laser modes; Optical pumping; Temperature; Thermomechanical processes
• ISSN: 2833-1052
• DOI: 10.1109/CLEO/Europe-EQEC57999.2023.10231721

High energy laser sources operating around 2\ \mu\mathrm{m} are of interest in variety of applications: LIDAR, material processing, medicine and pump sources for optical parametric oscillators (OPOs) for high-energy mid-IR non-linear conversion. Different laser configurations using Ho:YLF and Ho:YAG at room temperature have been used, but with thermal issues such as thermo optical and mechanical properties being limitations. Cryogenic cooling of Ho:YAG or Ho:YLF offers vast improvements in thermo-optical and thermo-mechanical properties of quasi three level gain media, but only moderate average powers and pulsed energies are achieved [1]-[3]. One of the key benefits from cryogenic cooling comes from the reduction of the thermal population of the lower lasing level, resulting in a four-level like behaviour. This significantly reduces the pump power required to achieve transparency and allows for much larger mode volumes to be used when compared to room-temperature operation of such lasers [4]-[5]. The high energy scaling with high repetition rate of the cryogenic or room temperature of Ho 3+ in YAG/YLF host is yet to be demonstrated.