• Upconversion laser produces 0.47 W of green light

    Based on photon avalanching and other processes, frequency upconversion is a method for creating short-wavelength lasers that does not involve nonlinear frequency conversion and its associated intensity-fluctuation problems.
    March 1, 2006

    Based on photon avalanching and other processes, frequency upconversion is a method for creating short-wavelength lasers that does not involve nonlinear frequency conversion and its associated intensity-fluctuation problems. Aiming for high-power upconversion at visible wavelengths, scientists at the Universität Hamburg (Hamburg, Germany) and Coherent Lambda Physic (Lübeck, Germany) have developed an upconversion laser based on erbium-doped lithium lutetium tetrafluoride (LiLuF4) that emits 0.47 W of continuous-wave power at a 552-nm wavelength, or a 0.76-W peak power at a 50% duty cycle. The room-temperature laser is pumped with 970-nm light from an optically pumped semiconductor (OPS) laser.

    The 1.6-mm LiLuF4 crystal is coated on one side to reflect highly at the pump wavelength and on the other to reflect highly at the upconversion wavelength; curved mirrors external to the crystal and a small angular offset of the pump beam result in a multipass pumping scheme. (The OPS pump laser emits up to 9 W with a beam parameter M2 between 2 and 2.5.) The upconversion laser has a threshold of 70 mW of absorbed pump power and a slope efficiency of 32%. Contact Ernst Heumann at [email protected].

    Sign up for Laser Focus World Newsletters
    Get the latest news and updates.

    Voice Your Opinion!

    To join the conversation, and become an exclusive member of Laser Focus World, create an account today!