High power and reliable 793nm T-bar and single emitter for thulium-doped fiber laser pumping

The 793nm semiconductor diode cladding pumped Thulium-doped high power fiber laser operates around eye safe 1.9 ~ 2μm and output power can reach to kW level. Those 2μm high power fiber lasers are attractive in various applications in industrial use, medical field, remote sensing and military use. High power, reliable 793nm diodes and cost-effective pump modules are the key component in enabling widespread use of Tm-doped 2μm fiber laser for commercial applications. The latest generation of Coherent AAA^TM epi design platform is optimized for low internal loss, high quantum efficiency and higher linear power density at 793nm region. Two types of high power diode lasers are tested; one is a single emitter with 100μm emission width and the other is a tailored bar (T-bar) including five 100μm emitters with 1mm pitch. The single emitter can achieve 5.6W output power at 5A with 1.26W/A slope efficiency and 60.3% E/O efficiency. Those single emitters are packaged and coupled into a 100μm fiber. At 5A current, a three single emitter based 100μm fiber-coupled module's output power is 13.4W and the E/O efficiency is 48.0%. The T-bar can reach up to 30W output power at 30A with 1.19W/A slope efficiency and 56.4% peak E/O efficiency. Nine T-bars are mounted and coupled into a 225μm fiber-coupled module and 150W output power and 47.3% E/O efficiency are achieved at 19.1A current. Both single emitter based and T-bar based fiber-coupled modules show long reliable life; single emitters based module's life is more than 20,000 h at 4A and T-bars based module's life is more than 10,000 h at 20A.