422 nm distributed feedback laser for a compact strontium ion optical clock

There is an ever-growing requirement for compact atomic devices, such as optical atomic clocks, taking them from a labscale technology to a more robust solution. Optical atomic clocks have made significant advances over the last few decades and represent the pinnacle of precision measurement technology. However, many systems make use of large, expensive lasers which are power hungry and often frequency doubled to hit key wavelengths or alternatively rely on vibration sensitive external cavity diode lasers (ECDL). New approaches and technologies are required such as working with ion-based optical clocks where small, robust ion traps can be realized with the ion cooling controlled using a distributed feedback (DFB) laser. A promising platform for an optical atomic clock is the strontium ion system due to its convenient wavelengths and simple level structure. Of the required lasers only the 422 nm cooling laser is not wellserved by existing technology. The National Physical Laboratory (NPL) are developing a compact ion trap physics package and vibrationally insensitive cubic cavity that will form the basis of the portable optical clock. DFB lasers have been realized at 422 nm with high output powers and narrow linewidths. Modelling of the device epitaxy and grating structure show how these devices can be improved further. Overall, this will significantly reduce the SWaP compared to current systems.