An important part of global integrated optics research focuses on the development of new, high-coherent, wide-band light sources, called frequency combs. These miniature and energy-efficient devices are intended to be embedded in compact diagnostic systems allowing the user to analyse chemical species, living cells, or to perform ultra-precise distance measurements. The generation of these frequency combs exploits the properties of nonlinear optics within ring resonators in which light will recirculate there to infinity. Research on s-frequency combs has been greatly accelerated over the past ten years thanks to the discovery of an ultra-robust temporal solution, the cavity soliton, capable of recirculating within the resonator over long times and supporting a frequency comb. The Solstice project proposes several scientific advances based on the emergence of ultra-short temporal structures in nonlinear resonators via the exploitation of polarisation modes. The miniaturisation and integration of these structures on an optical chip will allow the generation of frequency combs, and their application, at previously inaccessible scales.