Optical atomic clocks play a pivotal role in modern technology, influencing timekeeping, navigation, and global positioning systems. This project is dedicated to pioneering the world's first chip-scale all-optical atomic clock. It leverages recent breakthroughs in Kerr soliton micro-comb technology, chip-integrated picosecond mode-locked lasers, and highly efficient on-chip frequency doublers. It will create this based on recent advances in Kerr soliton micro-comb technology, ps mode-locked lasers that are heterogeneously integrated on a chip, and using novel on-chip frequency doublers with vastly improved efficiency. Exploitation of the Rb85 two-photon transition enables to obtain a clock signal that is two orders of magnitude improved compared to today’s radio frequency transition-based clocks. This clock can revolutionize timekeeping in mobile, airborne or space applications and used in future GPS networks such as Galileo. Moreover the underlying clockwork - a chipscale comb - can have applications ranging from distance measurements to time and frequency metrology.
Realizing this ambitious endeavor presents a multitude of challenges. To begin, the development of a Silicon Nitride (SiN) platform capable of integrating III-V materials is imperative. The theoretical models and designs are needed for achieving an octave-spanning Kerr soliton comb. The creation of a comprehensive set of new processes is essential, including the fabrication of a GaAs quantum dot amplifier and an AlGaAs second harmonic generation (SHG) device. Furthermore, the miniaturization of the rubidium-based spectroscopy setup to chip-scale dimensions is a task that requires meticulous engineering. This consortium brings together the leading groups in Europe in the domain of Frequency combs, micro-comb technology, and photonic chipscale laser integration. Their collective expertise is instrumental in addressing these formidable challenges and advancing the frontiers of optical atomic clock technology.
