Diode-pumped upconversion fiber laser produces more than 100 mW of blue light

Diode-pumped upconversion fiber laser produces more than 100 mW of blue light

Upconversion lasers are one approach to practical solid-state blue sources powered by diode lasers. Steve Sanders and coworkers at SDL Inc. (San Jose, CA) reported in postdeadline paper CPD23 at CLEO `95 in Baltimore, MD, an upconversion fiber laser that produces 106 mW of blue light. A pair of 0.5-W tunable diode lasers (tuned to 1130 nm) pumped a thulium-doped ZBLAN fluoride fiber. A lens focused the pum¥light into a 3-µm core, 2.5-m-long ZBLAN fluoride fiber doped with 0.1% thulium. They observed a threshold of 80 mW and generated 106 mW at 482 nm when pumping with 890 mW for an overall optical conversion efficiency of 12%. Pumping at 1137 nm increased the slope efficiency to 30%. Upconversion relaxes the requirements for a stable pum¥wavelength, which can be difficult with high-power diodes. The SDL team believes this may make the technique more attractive than direct doubling of diodes.