Probing Ca+ ions in a miniature trap

The electric quadrupole transition of confined Ca⁺ ions has been proposed as a frequency standard in the visible domain. To access metrologic conditions, we have built a cylindrical miniature trap, allowing to obtain high frequencies of motion and preparing the access to the Lamb-Dicke regime where the first order Doppler broadening is suppressed. Laser cooling and interrogation of the confined ions require lasers at 397 nm and at 729 nm. We propose the generation of these wavelengths using multimode laser diodes and a frequency-doubling set-up