Cold strontium atoms for an optical frequency standard

We report the capture of cold strontium atoms in a magnetooptical trap at a rate of 3×10¹⁰ atoms/s. This is achieved with high power laser light at 461 nm generated by sum frequency mixing in a potassium titanyl phosphate (KTP) crystal using diode lasers at 813 nm and a Nd:YAG laser at 1064 nm. Up to 115 mW of blue light is obtained. Tuned to the ¹S₀→¹P₁ of ⁸⁸Sr, this light is used both to slow down an atomic beam in a Zeeman slower and to capture the atoms in a magnetooptical trap. Trapping of ⁸⁷Sr and ⁸⁶Sr is also reported.