NPL and PTB have active teams with considerable experience, working on Yb+ ion traps for frequency standards. Both laboratories have an interest in generating 3.43 µm radiation to drive the 2F7/2 - 2D5/2 transition in Yb+. PTB is interested in the transition as a frequency standard in its own right. NPL is interested in driving the transition to depopulate the 2F7/2 state for two applications: (i) To allow the 411 nm 2S1/2 - 2D5/2 transition to be measured and investigated as a potential frequency standard, and (ii) To aid the search for the 467 nm 2S1/2 - 2F7/2 transition which is also a potential frequency standard.
The collaboration would cover the exchange of information and ideas aimed at developing a compact source to drive the 3.43 µm transition in Yb+. PTB have identified and tested an iodine laser which might be suitable, but its output needs to be shifted by about 31.4 GHz. One possibility might be for PTB to concentrate on the iodine laser while NPL concentrates on the shifter. Other options might be considered.