Watt-level blue light for precision spectroscopy, laser cooling and trapping of strontium and cadmium atoms

Abstract

<p>High-power and narrow-linewidth laser light is a vital tool for atomic physics, being used for example in laser cooling and trapping and precision spectroscopy. Here we produce Watt-level laser radiation at 457.75 nm and 460.86 nm of respective relevance for the cooling transitions of cadmium and strontium atoms. This is achieved via the frequency doubling of a kHz-linewidth vertical-external-cavity surface-emitting laser (VECSEL), which is based on a novel gain chip design enabling lasing at > 2 W in the 915-928 nm region. Following an additional doubling stage, spectroscopy of the <sup>1</sup>S<sub>0</sub> → <sup>1</sup>P<sub>1</sub> cadmium transition at 228.87 nm is performed on an atomic beam, with all the transitions from all eight natural isotopes observed in a single continuous sweep of more than 4 GHz in the deep ultraviolet. The absolute value of the transition frequency of <sup>114</sup>Cd and the isotope shifts relative to this transition are determined, with values for some of these shifts provided for the first time.</p>