Yb fiber amplifier at 972.5 nm with frequency quadrupling to 243.1 nm

Abstract

We demonstrate a continuous-wave ytterbium-doped fiber amplifier which produces 6.3 W at a wavelength of 972.5 nm. We frequency quadruple this source in two resonant doubling stages to produce 530 mW at 243.1 nm. Radiation at this wavelength is required to excite the 1S-2S transition in atomic hydrogen and could therefore find application in experimental studies of hydrogen and anti-hydrogen

Frequency-Stabilized Deep-UV Laser at 243.1 nm with 1.4 W output power

“…Our laser system, shown in Fig. 1 and described in more detail in [16], starts with a frequency-stabilized extended cavity diode laser (ECDL), which operates at 972.5 nm. The output of the ECDL is then amplified in two stages: first with a commercial tapered amplifier, and then with a double-clad Yb-doped fiber amplifier.…”

“…The EOM directly before the TA provides the necessary modulation for locking these stages on resonance the Pound-Drever Hall method. A more detailed discussion of this system is given in [16].…”

“…Overall, we believe this system is still power scalable with more pump power. However, the free-space coupling of both the seed and pump light [16] requires significant thermal management of the fiber mount and coupling lens mounts as Fresnel reflections off the fiber tips and scatter off the optics heats these components. We currently address these issues using radiation shields and water cooling.…”

“…We currently address these issues using radiation shields and water cooling. The amplified radiation is then sent through successive resonant doubling stages, which are described in more detail in [16], generating 486.3 nm and 243.1 nm, respectively. The first resonant doubling stage uses a 25 mm long LBO crystal, a 3% input coupler, and 150 mm radius of curvature mirrors that generate a beam waist of ≈ 50 µm within the crystal.…”

“…Motivated by improving spectroscopy of simple and exotic atoms, laser cooling hydrogen, and the general utility of a high-power deep-UV laser, we previously developed a Yb-fiber amplifier tunable from 972-976 nm [11,16]. This system was able to generate ≈ 6 W of 972-976 nm radiation limited by the available pump power (50 W).…”